CA2877642C

CA2877642C - Pneumatic tire

Info

Publication number: CA2877642C
Application number: CA2877642A
Authority: CA
Inventors: Takahiro Yamakawa
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2012-11-15
Filing date: 2013-11-13
Publication date: 2017-03-21
Anticipated expiration: 2033-11-13
Also published as: CA2877642A1; WO2014077271A1; JP5786964B2; JPWO2014077271A1

Abstract

A tread pattern on a pneumatic tire is provided with circumferential shallow grooves extending in the tire circumferential direction in regions of two intermediate land portions. An orientation of a groove inclination with respect to a first direction in the tire circumferential direction of lug grooves provided in a region of one intermediate land portion, is the same as an orientation of a groove inclination with respect to a second direction opposite to of the first direction of the tire circumferential direction of lug grooves provided in a region of another intermediate land portion, and the lug grooves provided in the respective regions of the intermediate land portions are bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves. Lug grooves provided in the inside land portion extend in an orientation of a groove inclination that is different with respect to the tire circumferential direction from the lug grooves provided in the respective regions of the intermediate land portions.

Description

PNEUMATIC TIRE
TECHNICAL FIELD
[0001]
The present invention relates to a pneumatic tire provided with a tread pattern.
BACKGROUND

[0002]
A conventional tire is known that is used all year long as an all-season tire and that has four circumferential main grooves, a region of inside land portion partitioned by two inner circumferential main grooves on the inside, and regions of two intermediate land portions partitioned by outer circumferential main grooves and the inner circumferential main grooves (see Patent Document 1). In the tire in Patent Document 1, lug grooves are provided in the region of the inside land portion and in the regions of the intermediate land portions, and the lug grooves in the regions of the two intermediate land portions extend in an inclined manner in the same orientation with respect to the tire circumferential direction, and the lug grooves in the region of the inside land portion extend in an inclined manner in a different orientation with respect to the tire circumferential direction than the lug grooves in the regions of the intermediate land portions. Snow performance is maintained while dry performance can be improved in the tire according to Patent Document 1.
PRIOR ART DOCUMENT
Patent Document

[0003]

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-168006A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention

[0004]
An all-season tire is desirably provided with a tire performance that can handle various road surface conditions such as dry, wet, or snow-covered road surfaces. However, the tire in Patent Document 1 does not exhibit a sufficient balance in abrasion resistance on dry road surfaces, wet performance, and snow performance. Specifically, abrasion resistance on dry road surfaces decreases when wet turning performance and steering stability on snow are improved.
The present invention provides a pneumatic tire having an excellent balance in abrasion resistance on dry road surfaces, wet turning performance, and steering stability on snow.
Means to Solve the Problem

[0005]
One aspect of the present invention is a pneumatic tire. The pneumatic tire includes:
a bead;
a side wall;
a belt layer;
a carcass layer; and a tread portion having a tread pattern; wherein the tread pattern includes:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves; wherein an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions is identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions have a curved portion that is curved so that the groove inclination approaches the tire circumferential direction at a position of intersection with the circumferential shallow groove; and lug grooves that are provided in the inside land portion extend in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction.

[0006]
The respective regions of the intermediate land portions preferably have sipes that extend so as to be parallel to the lug grooves provided in the respective regions of the intermediate land portions, and the sipes are blocked within the intermediate land portions without connecting with the inner circumferential main grooves.

[0007]
The sipes preferably extend in a zigzag manner while deflecting in a direction orthogonal to an extension direction of the sipes in the tire width direction and extend in a zigzag manner while deflecting in a direction orthogonal to a sipe depth direction of the sipes from a tread surface toward a bottom portion of the sipes in a region on the inner side of the circumferential shallow grooves.

[0008]
The sipes preferably extend in a linear manner in a region on the outer side of the circumferential shallow grooves in the tire width direction, and extend in a planar manner in a depth direction of the sipes from a tread surface toward a bottom portion of the sipes.

[0009]
Moreover, shoulder land portions are provided in regions on the outer side of the circumferential main groove group in the tire width direction, and regions of the shoulder land portions have shoulder lug grooves, provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, and the shoulder lug grooves are blocked part way through without connecting with the outer circumferential main grooves, whereby the shoulder land portions preferably form continuous land portions that extend continuously in the tire circumferential direction.

[0010]
Moreover, shoulder land portions are provided in regions on the outer side of the circumferential main groove group in the tire width direction, and regions of the shoulder land portions have shoulder lug grooves provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, and a maximum groove width of the shoulder lug grooves is preferably greater than a maximum groove width of the lug grooves provided in the region of the inside land portion and in the regions of the intermediate land portions.

[0011]
The shoulder land portions are provided with shoulder sipes provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, and the shoulder sipes include a first portion extending in a linear manner in an extension direction of the shoulder sipes and extending in a planar manner in a sipe depth direction of the shoulder sipes from a tread surface toward a bottom portion of the shoulder sipes, and a second portion extending in a zigzag manner while deflecting in a direction orthogonal to the extension direction of the shoulder sipes and extending in a zigzag manner while deflecting in a direction orthogonal to a sipe depth direction of the shoulder sipes from a tread surface toward the bottom portion, and the shoulder sipes change from the first portion to the second portion while advancing from the outer side in the tire width direction toward the outer circumferential main grooves and then end.

[0012]
A portion of an edge portion in contact with the circumferential main grooves in the inside land portion and the intermediate land portions is preferably provided with a chamfer.

[0013]
A width of a land portion in a region on the inner side of the circumferential shallow grooves in the tire width direction is preferably greater than a width of a land portion in a region on the outer side of the circumferential shallow grooves in the tire width direction in the intermediate land portions.
EFFECT OF THE INVENTION

[0014]
The tire of the present invention demonstrates an excellent balance of abrasion resistance on dry road surfaces, wet turning performance, and steering stability on snow. That is, abrasion resistance on dry road surfaces is maintained while demonstrating excellent wet turning performance and steering stability on snow.
BRIEF DESCRIPTION OF THE DRAWINGS

[0015]
FIG. 1 is a visual appearance view of an entire tire of an embodiment of the present invention.
FIG. 2 is a meridian cross-sectional view of a portion of the tire illustrated in FIG. 1.
FIG. 3 is a view as seen in plan development view to allow for easy understanding of a tread pattern of the tire of the embodiment.
FIG. 4 is an enlarged view focusing on an inside land portion and intermediate land portions in the tread pattern illustrated in FIG. 3.
FIG. 5A is a cross-sectional view along the line Va¨Va illustrated in FIG.
3 of the tread surface of the tire of the embodiment.
FIG. 5B is a cross-sectional view along the line Vb¨Vb illustrated in FIG.
3 of the tread surface of the tire of the embodiment.

FIG. 6A is a view of an enlargement of a region A illustrated in FIG. 4.
FIG. 6B is a view of an enlargement of a region B illustrated in FIG. 4.
FIG. 6C is a view of an enlargement of a region C illustrated in FIG. 4.
BEST MODE FOR CARRYING OUT THE INVENTION

[0016]
The following is a detailed description of the pneumatic tire according to the present invention.
FIG. 1 illustrates a visual appearance of a pneumatic tire 1 of an embodiment of the present invention.
The pneumatic tire (hereafter referred to as a tire) 1 is a tire for a passenger car.
The structure and rubber members of the tire 1 of the present invention may be either publicly known or novel, and are not particularly limited in the present invention.

[0017]
As illustrated in FIG. 2, the tire 1 includes a tread portion 2, a side wall 3, a bead 4, a carcass layer 5, and a belt layer 6. FIG. 2 is a meridian cross-sectional view illustrating a portion of the tire 1. In addition, the tire 1 includes an inner liner layer, and the like, that are not illustrated in the drawings.
The side wall 3 and the bead 4 are each formed as pairs that are arranged on both sides in the tire width direction so as to sandwich the tread portion 2.
The tread portion 2, the bead 4, the belt layer 6, the inner liner, and the like may be either publicly known or novel, and are not particularly limited in the present invention.

[0018]
The tire 1 of the present invention has a tread pattern 10 formed in the tread portion as illustrated in FIG. 3. FIG. 3 is a view as seen in plan development view to allow for easy understanding of the tread pattern 10 of the tire 1 of the present invention. The tire 1 having the tread pattern 10 may be suitably used as a tire for a passenger car. The dimensions of circumferential main grooves, lug grooves, sipes, ground contact widths, chamfers, circumferential shallow grooves, shoulder lug grooves, and land portion blocks which are explained below are numerical examples for a tire for a passenger car.

[0019]
The tire 1 of the present invention has information of a tire mounting orientation, which side of the tire faces outward from the vehicle, predetermined. The reference numeral CL in FIG. 3 refers to a tire equatorial line. While the tire 1 is mounted so that the region of the tread pattern 10 on the left side of the tire equatorial line CL in FIG. 3 is located inward to a vehicle, and the region of the tread pattern 10 on the right side of the tire equatorial line CL in FIG. 3 is located outward from the vehicle, the tire may be mounted so that the regions are located inward to and outward from the vehicle in the reverse manner.

[0020]
While the tire 1 is mounted on a vehicle, the tread pattern 10 comes into contact with the road surface in a region in the tire width direction indicated by a ground contact width 11w. Note that the hatched regions in the tread pattern are regions further outside in the tire width direction than ground contact edges.
The ground contact edges are determined as described below. The ground contact edges are end portions in the tire width direction of a ground contact patch when the tire 1 is brought into contact with a horizontal surface under conditions in which the tire 10 is fitted to a regular rim and inflated to a regular inner pressure of 180 kPa, and a load to be applied is set to 88% of a regular load. Herein, "regular rim" includes a "standard rim" defined by the Japan Automobile Tyre Manufacturers Association Inc. (JATMA), a "design rim" defined by the Tire and Rim Association, Inc. (TRA), and a "measuring rim" defined by the European Tyre and Rim Technical Organisation (ETRTO).
While "regular inner pressure" includes "maximum air pressure" defined by JATMA, the maximum value in "tire load limits at various cold inflation pressures" defined by TRA, and "inflation pressures" defined by ETRTO, the regular inner pressure is set to 180 kPa when the tire is for a passenger car.

Note that "regular load" includes "maximum load resistance" defined by JATMA, the maximum value in "tire load limits at various cold inflation pressures" defined by TRA, and "load capacity" defined by ETRTO.

[0021]
The tire width direction in the present invention refers to an extension direction of the rotational center axis of the tire 1, and the tire circumferential direction refers to a rotation direction of the rotation surface of the tread surface, the rotation surface being formed when the tire 1 rotates around the tire rotational center axis. The above directions are expressed in FIG. 3. The tire rotation direction of the tread pattern 10 of the present invention is not particularly limited.
The tire 1 of the present invention may have a pitch with the same dimensions as the tread pattern 10 arranged in the tire circumferential direction, or the tire 1 may have a plurality of types of pitches with different dimensions from the tread pattern 10 arranged in the tire circumferential direction to allow for a pitch variation.

[0022]
The tread pattern 10 is provided with a circumferential main groove group including four circumferential main grooves 11, 13, 15, 17 parallel to the tire circumferential direction, lug grooves 31, 33, 35, and circumferential shallow grooves 41, 43.

[0023]
(Circumferential main groove group) The circumferential main groove group includes two outer circumferential main grooves 11, 13 and two inner circumferential main grooves 15, 17. The outer circumferential main grooves 11, 13 are disposed on the outer side in the tire width direction of the inner circumferential main grooves 15, 17. The two inner circumferential main grooves 15, 17 are disposed so as to be interposed between the outer circumferential main grooves 11, 13. The tire center line CL runs between the inner circumferential main groove 15 and the inner circumferential main groove 17 in the tire width direction. The groove depths of the outer circumferential main grooves 11, 13 and the inner circumferential main grooves 15, 17 are the same each other, but may be different in another embodiment. The total amount of the groove widths of the outer circumferential main grooves 11, 13 and the inner circumferential main grooves 15, 17 is preferably from 15 to 25% of the ground contact width llw from the point of view of wet performance.

[0024]
(Lug grooves) The lug grooves 31, 33, 35 are grooves that cross the region of an inside land portion 21 and the region of intermediate land portions 23, 25. Each of the lug grooves 31, 33, 35 has a plurality of grooves spaced with intervals in the tire circumferential direction. The lug grooves 31, 33, 35 may each extend in a substantially straight line or may extend in a moderately curved manner.
Groove widths 31w, 33w, 35w of the respective lug grooves 31, 33, 35 are all the same in the tire width direction and are, for example, from 2 to 7 mm.

[0025]
Now, the inside land portion 21 and the intermediate land portions 23, 25 are explained.
The inside land portion 21 is a portion formed by being partitioned by the two inner circumferential main grooves 15, 17. The tire center line CL
passes through the region of the inside land portion 21. A plurality of land portion blocks 22 is formed by the lug grooves 31 in the tire circumferential direction in the region of the inside land portion 21. The lug grooves 31 extend in an inclined manner at an inclination angle Oce with respect to an X2 direction of the tire circumferential direction as illustrated in FIG. 4. FIG.
4 is an enlarged view of a portion of the tread pattern 10. The inclination angle Oce is, for example, from 60 to 85 . Due to the inclination angle being closer to the tire width direction than the tire circumferential direction in this way, a high block rigidity of the land portion blocks 22 can be achieved, and wet turning performance and steering stability on snow can be improved with a small steering angle while the vehicle is traveling. Note that when the lug grooves 31 extend in a moderately curved manner, the inclination angle Oce represents an inclination with respect to the direction of a straight line connecting two center points at center positions in the width direction of the lug groove 31 in respective portions connecting the inner circumferential main groove 15 and the outer circumferential main groove 17.

[0026]
The intermediate land portion 23 is a portion formed by being partitioned by the outer circumferential main groove 11 and the inner circumferential main groove 15. A plurality of land portion blocks 24 is formed in the tire circumferential direction in the region of the intermediate land portion 23 by the lug grooves 33. Furthermore, the intermediate land portion 25 is a portion formed between the outer circumferential main groove 13 and the inner circumferential main groove 17 by being partitioned by the outer circumferential main groove 13 and the inner circumferential main groove 17.
A plurality of land portion blocks 26 is formed in the tire circumferential direction in the region of the intermediate land portion 25 by the lug grooves 35.

[0027]

When the lug grooves 33 and the lug grooves 35 advance from the outer side in the tire width direction to the inner side, an orientation of a groove inclination with respect to an X2 direction (a first direction of the tire circumferential direction) of the lug grooves 33 is the same as an orientation of a groove inclination with respect to an X1 direction (a second direction that is the opposite direction of the first direction of the tire circumferential direction) of the lug grooves 35. In other words, the lug grooves 33 and the lug grooves 35 are inclined in the same orientation with respect to the X1 direction and the X2 direction of the tire circumferential direction, respectively. Note that the orientation of a groove inclination expresses a distinction between whether the groove inclination is in a range of 900 to 0 or in a range of 00 to 90 within a range of -90 (900 in the counterclockwise direction) to 90 (90 in the clockwise direction) with respect to the X1 direction or the X2 direction of the tire circumferential direction, and grooves inclined in the same range exhibit the same orientation of the groove inclination, and grooves inclined in different angle ranges exhibit different orientations of the groove inclination.
Conversely, the above mentioned lug grooves 31 extend in inclining orientation which is different from inclining orientation of the lug grooves 33, 35 inclination with respect to the tire circumferential direction.
Maneuverability when turning left or right is assured by the above inclining orientations of the grooves.

[0028]
When the lug grove 33 advances from the outer side in the tire width direction to the inner side in the tire width direction, the lug grooves 33 are bent so that the groove inclination approaches the tire circumferential direction at a position P (see FIG. 4) where the lug grooves 33 intersect the circumferential shallow groove 41. Specifically, as illustrated in FIG. 4, the lug grooves 33 are inclined at an inclination angle Oml with respect to the X2 direction on the outer side in the tire width direction of the position P and are inclined at an inclination angle 0m2 with respect to the X1 direction on the inner side in the tire width direction of the position P. The inclination angle 0m2 is less than the inclination angle Oml. As a result, while the lug grooves 33 advance from the outer side in the tire width direction to the inner side in the tire width direction, the lug grooves 33 are bent so that the groove inclination approaches the tire circumferential direction. The inclination angle Oml of the groove inclination is, for example, from 60 to 85 . The inclination angle 0m2 is, for example, from 30 to 50 . Due to the lug grooves 33 having two types of inclination angles in this way, when turning with a low steering angle to an intermediate steering angle while the vehicle is traveling on dry road surfaces, wet road surfaces, and snow-covered road surfaces, excellent turning and stability can be achieved. Note that the inclination angle Oml refers to an inclination with respect to the tire circumferential direction of a straight line connecting two center points at center positions in the groove width direction of the lug grooves 33 in respective portions where the lug grooves 33 connect to the outer circumferential main groove 11 and the circumferential shallow groove 41 when the inner portion with respect to the circumferential shallow groove 41 of the lug grooves 33 extends in a moderately curved manner.
Furthermore, the inclination angle 0m2 when the lug grooves 33 extend in a moderately curved manner refers to an inclination with respect to the tire circumferential direction of a straight line connecting two center points at center positions in the groove width direction of the lug grooves 33 in respective portions where the lug grooves 33 connect to the inner circumferential main groove 15 and the circumferential shallow groove 41.

[0029]
When the lug grove 35 advances from the outer side in the tire width direction to the inner side in the tire width direction, the lug grooves 35 are bent so that the groove inclination approaches the tire circumferential direction at a position Q (see FIG. 4) where the lug grooves 35 intersect the circumferential shallow groove 43. Specifically, as illustrated in FIG. 4, the lug grooves 35 are inclined at the inclination angle Om 1 with respect to the X1 direction on the outer side in the tire width direction of the position Q and are inclined at the inclination angle 0m2 with respect to the X2 direction on the inner side in the tire width direction inner side of the position Q. Note that when the inner portions with respect to the circumferential shallow groove 43 of the lug grooves 35 extend in a moderately curved manner, the inclination angle 0m1 refers to an inclination with respect to the tire circumferential direction of a straight line connecting two center points at center positions in the groove width direction of the lug grooves 35 in respective portions where the lug grooves 35 connect to the outer circumferential main groove 13 and the circumferential shallow groove 43. Furthermore, when the lug grooves 35 extend in a moderately curved manner, the inclination angle 0m2 refers to an inclination with respect to the tire circumferential direction of a straight line connecting two center points at center positions in the groove width direction of the lug grooves 35 in respective portions where the lug grooves 35 connect to the inner circumferential main groove 17 and the circumferential shallow groove 43. In another embodiment of the lug grooves 35, the inclination angle on the outer side in the tire width direction of the position Q may be larger than the inclination angle on the inner side in the tire width direction of the position Q, or the inclination angle on the inner side in the tire width direction of the position Q may be smaller than the inclination angle on the outer side in the tire width direction of the position Q.

[0030]
The region of the intermediate land portion 23 on the inner side in the tire width direction of the circumferential shallow groove 41 is preferably wider in the tire width direction than the region on the outer side in the tire width direction of the circumferential shallow groove 41 from the point of view of assuring high block rigidity. The region of the intermediate land portion 25 on the inner side in the tire width direction of the circumferential shallow groove 43 is preferably wider in the tire width direction than the region in the outer side in the tire width direction of the circumferential shallow groove 43 from the same point of view.

[0031]
(Circumferential shallow grooves) The circumferential shallow grooves 41, 43 are respectively provided in the intermediate land portions 23, 25 and extend in the tire circumferential direction.
The circumferential shallow grooves 41, 43 have raised bottoms and thus have a shallower groove depth than the circumferential main grooves 11, 13, 15, 17. As a result, block rigidity and abrasion resistance on dry road surfaces of the intermediate land portions 23, 25 can be obtained while improving wet turning performance. The groove depth of the circumferential shallow grooves 41, 43 is preferably within 70%, more preferably from 30% to 50% of the groove depth of the circumferential main grooves 11, 13, 15, 17 from the point of view of assuring abrasion resistance.
Furthermore, the groove width of the circumferential shallow grooves 41, 43 is preferably from 5 to 15% of the length (width) in the tire width direction of the intermediate land portions 23, 25. Note that the length in the tire width direction of the intermediate land portions 23, 25 refers to the maximum length in the tire width direction of the land portion blocks 24, 26 on the tread surface.
Furthermore, the circumferential shallow grooves 41, 43 are preferably provided in positions in the tire width direction which are located 40% or more to less than 50% of the overall length (width) in the tire width direction of each of the intermediate land portions 23, 25 from the edges on the outer side in the tire width direction of the intermediate land portions 23, 25 to the edges on the inner side in the tire width direction due to abrasion resistance. That is, the width of land portions in the regions of the intermediate land portions 23, 25 on the inner side in the tire width direction of the circumferential shallow grooves 41, 43 is preferably greater than the width of land portions in the regions of the intermediate land portions 23, 25 on the outer side in the tire width direction of the circumferential shallow grooves 41, 43.
Note that the circumferential shallow grooves are preferably not provided in the region of the inside land portion 21 and in the regions of the below-mentioned shoulder land portions 51, 53. The reason is the following.
The land portions 21, 51, 53 contribute greatly to wet turning performance and steering stability on snow when braking and driving, but both wet turning performance and abrasion resistance on dry road surfaces cannot be achieved if the circumferential shallow grooves are provided in the land portions 21, 51, 53.

[0032]
(Sipes) The tread pattern 10 further includes sipes 34, 36.
In the present invention, the sipes have a width of less than 1.5 mm and have a groove depth of less than 5 mm. Furthermore, the lug grooves have a groove width of 1.5 mm or more and have a groove depth of 5 mm or more.
The sipes 34, 36 are grooves that extend so as to be parallel to the lug grooves 33, 35 in the respective intermediate land portions 23, 25. The sipes 34, 36 are each provided as two sipes in one land portion block 24, 26. Note that, in another embodiment, the number of the sipes 34, 36 in one land portion block 24, 26 may be one or may be three or more.

[0033]
The sipes 34, 36 are respectively blocked within the intermediate land portions 23, 25 without connecting with the inner circumferential main grooves 15, 17. As a result, abrasion resistance on dry road surfaces can be improved.

The sipes 34, 36 extend in a zigzag manner while deflecting in a direction orthogonal to the extension direction of the sipes 34, 36 in the regions on the inner side in the tire width direction of the circumferential shallow grooves 41, 43 and, as illustrated in FIG. 5A, extend toward the bottom portion in a zigzag manner while deflecting in a direction (left-right direction in drawing in FIGS.
5A to 5C) orthogonal to the sipe depth direction (direction from bottom to top in drawing in FIGS. 5A to 5C) from the tread surface toward the bottom portion.
This shape of the sipes 34, 36 in the regions on the inner side in the tire width direction is also referred to hereinbelow as a three-dimensional shape. FIG.
5A is a view of line Va-Va in FIG. 3 and illustrates the state in which the tread portion 2 is in contact with a horizontal plane. Note that the reference numerals represented in parentheses in FIGS. 5A to 5C are for indicating elements in the region of the intermediate land portion 25 for ease of description.
The respective regions on the inner side in the tire width direction of the circumferential shallow grooves 41, 43 in the land portion blocks 24, 26 have an inclination angle with respect to the tire circumferential direction of the lug grooves 33, 35 less than in the regions on the outer side in the tire width direction of the circumferential shallow grooves 41, 43 whereby block rigidity is reduced. As a result, block rigidity when braking and driving is configured to be strengthened due to the above-mentioned three-dimensional shape of the regions of the sipes 34, 36 on the outer side in the tire width direction of the circumferential shallow groove 41, 43.

[0034]
The sipes 34, 36 are respectively connected with the outer circumferential main grooves 11, 13. The sipes 34, 36 preferably extend in a linear manner respectively in the regions on the outer side in the tire width direction of the circumferential shallow grooves 41, 43 and, as illustrated in FIG.
5B extend in a planar manner in the sipe depth direction from the tread surface to the bottom portion. This shape of the sipes 34, 36 in the regions of the outer side in the tire width direction is also referred to hereinbelow as a two-dimensional shape. FIG. 5B is a view of line Vb-Vb in FIG. 3 and illustrates the state in which the tread portion 2 is in contact with a horizontal plane. Furthermore, a shape in which the sipes 34, 36 extend in a linear manner does not include a shape in which the sipes 34, 36 extend in a zigzag manner, but includes a shape in which the sipes 34, 36 extend along a straight line and, for example, a shape in which the sipes 34, 36 extend in a moderately curved manner. Consequently, an extension of the sipes 34, 36 in a planar manner includes an extension along a flat plane and, for example, an extension along a moderately curved plane.

[0035]
The tread pattern 10 further includes sipes 32.
The sipes 32 are grooves that extend so as to be parallel to the lug grooves 31 in the region of the inside land portion 21. The sipes 32 are provided as two sipes in one land portion block 22. Note that, in another embodiment, the number of the sipes 32 in one land portion block 22 may be one or may be three or more. The sipes 32 have a three-dimensional shape, thereby strengthening the block rigidity of the inside land portion 21 during braking and driving. The sipes 32 connect with the inner circumferential main grooves 15, 17. Note that, in another embodiment, the sipes 32 may have the two-dimensional shape and may be blocked within the inside land portion 21 without connecting with the inner circumferential main grooves 15, 17.

[0036]
(Shoulder land portions) The tread pattern 10 further has a shoulder land portion 51 on the outer side in the tire width direction of the outer circumferential main groove 11.
Furthermore, the tread pattern 10 further has a shoulder land portion 53 on the outer side in the tire width direction of the outer circumferential main groove 13.

The regions of the shoulder land portions 51, 53 are respectively provided with shoulder lug grooves 61, 63 extending from the outer side in the tire width direction toward the outer circumferential main grooves 11, 13. The shoulder lug grooves 61, 63 are respectively blocked part way through without connecting with the outer circumferential main grooves 11, 13. As a result, the shoulder land portions 51, 53 form continuous land portions that continuously extend in the tire circumferential direction. Since the shoulder land portions 51, 53 contribute greatly to braking performance and turning performance, the formation of such continuous land portions allows a reduction in block rigidity of the shoulder land portions 51, 53 to be suppressed and allows abrasion resistance on dry road surfaces to be improved. Note that the shoulder land portions 51, 53 preferably form the continuous land portions on the sides in contact with the outer circumferential main grooves 11, 13 from the point of view of assuring good wet turning performance and steering stability on snow.
Note that the distance between the shoulder lug groove 61 and the outer circumferential main groove 11 in the region of the shoulder land portion 51, that is, the width of a portion in which two adjacent blocks are joined in the tire circumferential direction to form the continuous land portions (joined width) is preferably from 5% to 20% of the length in the tire width direction between the outer circumferential main groove 11 and the ground contact edge. The length is, for example, 15% in the present embodiment. Similarly, the distance between the shoulder lug groove 63 and the outer circumferential main groove 13 in the region of the shoulder land portion 53 (joined width) is preferably from 5% to 20% of the length in the tire width direction between the outer circumferential main groove 13 and the ground contact edge. The length is, for example, 15% in the present embodiment.

[0037]

The tips of the shoulder lug grooves 61, 63 on the inner side in the tire width direction are formed in a tapered shape. Maximum groove widths 61w, 62w of the respective shoulder lug grooves 61, 63 are greater than the groove widths (maximum groove widths) 31w, 33w, 35w of the respective lug grooves 31, 33, 35, and are, for example, from 4 to 8 mm. Thus, wet turning performance and steering stability on snow are improved due to the greater groove width of the shoulder land portions 51, 53 that contribute greatly while braking and driving. Note that the maximum groove width 61w of the shoulder lug grooves 61 and the maximum groove width 62w of the shoulder lug grooves 63 may be the same or different.
The shoulder lug grooves 61 extend in an inclined manner at Osh (see FIG. 4) with respect to the X1 direction of the tire circumferential direction, for example, at from 75 to 90 . The shoulder lug grooves 63 extend in an inclined manner at Osh (see FIG. 4) with respect to the X2 direction of the tire circumferential direction, for example, at from 75 to 90 . Due to the shoulder lug grooves 61, 63 having inclination angles closer to the tire width direction with respect to the tire circumferential direction in this way, a high block rigidity of the shoulder land portions 51, 53 is assured and wet turning performance and steering stability on snow with a low steering angle is improved. As illustrated in FIG. 4, the inclination angle Osh of the shoulder lug grooves 61, 63 represents an inclination with respect to the tire circumferential direction of a straight line connecting a point at the center position of the width of the shoulder lug grooves 61, 63 in the tire circumferential direction at the ground contact edge and a point at the center position in the tire circumferential direction at an end portion on a side with the outer circumferential main grooves 11, 13. Note that the inclination angles of the shoulder lug grooves 61, 63 may be the same or different.

[0038]

Furthermore, sipes 62, 64 are respectively provided in the regions of the shoulder land portions 51, 53. Two sipes 62, 64 are provided between two adjacent shoulder lug grooves 61, 63 in the tire circumferential direction.
The number of the sipes 62, 64 provided in the shoulder land portions 51, 53 between the two adjacent shoulder lug grooves 61, 63 may be one or may be three or more in another embodiment. Furthermore, the sipes 62, 64 preferably have the three-dimensional shape on the inner side in the tire width direction of the ground contact edge and preferably have the two-dimensional shape on the outer side in the tire width direction of the ground contact edge.
The rigidity of the shoulder land portions 51, 53 during braking and driving can be improved due to the sipes 62, 64 having the three-dimensional shape on the inner side in the tire width direction of the ground contact edge.
Alternatively, the sipes 62, 64 include a two-dimensional shape portion (first portion) that extends in a linear manner in the extension direction of the shoulder sipes 62, 64 and extends in planar manner in the sipe depth direction from the tread surface of the sipes 62, 64 to the bottom portion of the sipes 62, 64, and a three-dimensional shape portion (second portion) that extends in a zigzag manner while deflecting in a direction orthogonal to the extension direction of the sipes 62, 64 and extends toward the bottom portion in a zigzag manner while deflecting in a direction orthogonal to the sipe depth direction from the tread surface of the sipes 62, 64 toward the bottom portion of the sipes 62, 64, and the sipes 62, 64 change from the two-dimensional shape portion to the three-dimensional shape portion while advancing from the outer side in the tire width direction toward the outer circumferential main grooves 11, 13 and then end. The rigidity of the shoulder land portions 51, 53 during braking and driving can be improved due to the sipes 62, 64 having the three-dimensional shape on the sides close to the outer circumferential main grooves 11, 13.

[0039]
(Chamfers) The tread pattern 10 further has chamfers 21a, 23a, 25a, 51a, 53a.
As illustrated in FIG. 4, chamfers 21a are provided on some of the edge portions of the inside land portion 21 in contact with the inner circumferential main grooves 15, 17. As a result, an edge amount of the inside land portion 21 is increased, and wet turning performance and steering stability on snow are improved. Conversely, since the chamfers 21a are provided on some of the edge portions, the block rigidity is not excessively reduced, and abrasion resistance on dry road surfaces is assured.
The chamfers 21a are provided on both sides in the tire width direction of each of the land portion blocks 22 as illustrated in FIG. 6B, and the chamfers 21a are each machined so that a chamfer depth thereof is greater toward both sides in the tire circumferential direction. FIG. 6B is an enlarged view of a region encircled by B in FIG. 4 for explaining the chamfer 21a. The depth of the chamfer 21a is preferably 50% or less, more preferably from 10% to 30% of the groove depth of the inner circumferential main grooves 15, 17 from the point of view of abrasion resistance.

[0040]
As illustrated in FIG. 4, chamfers 23a are provided on some of the edge portions of the intermediate land portion 23 in contact with the outer circumferential main groove 11. Furthermore, chamfers 25a are provided on some of the edge portions of the intermediate land portion 25 in contact with the outer circumferential main groove 13. In such a configuration, edge amounts of the intermediate land portions 23, 25 are increased, and wet turning performance and steering stability on snow are improved. Furthermore, since the chamfers 23a, 25a are provided on some of the edge portions, the block rigidity is not excessively reduced and abrasion resistance on dry road surfaces is assured. FIG. 6C is an enlarged view of a region encircled by C in FIG. 4 for explaining the chamfer 25a. Note that the reference numerals represented in parentheses in FIG. 6C are for indicating the elements in the region of the intermediate land portion 23 for ease of description. The chamfers 23a may be provided on the edge portions of the intermediate land portion 23 in contact with the inner circumferential main groove 15. Furthermore, the chamfers 25a may be provided on the edge portions of the intermediate land portion 25 in contact with the inner circumferential main groove 17. The depth of the chamfers 23a, 25a is preferably 50% or less, and more preferably from 10% to 30% of the groove depth of the circumferential main grooves 11, 13, 15, 17 from the point of view of abrasion resistance.

[0041]
As illustrated in FIG. 4, chamfers 51a, 53a are respectively provided on some of the edge portions in contact with the outer circumferential main grooves 11, 13 of the shoulder land portions 51, 53. As a result, edge amounts of the shoulder land portions 51, 53 are increased, and wet turning performance and steering stability on snow are improved. The reason why the chamfers 51a, 53a are provided is to assure abrasion resistance on dry road surfaces without excessively reducing the rigidity of the shoulder land portions 51, 53 as some of edges. The chamfers 51a, 53a each have two surfaces adjacent to each other in the tire circumferential direction and having different inclinations as illustrated in FIG. 4 and FIG. 6A. FIG. 6A is an enlarged view of a region encircled by A in FIG. 4 for explaining the chamfer 51a. Note that the reference numerals represented in parentheses in FIG. 6A are for indicating the elements in the region of the shoulder land portion 53 for ease of description.
The depth of the chamfers 51a, 53a is preferably 50% or less, and more preferably from 10% to 30% of the groove depth of the circumferential main grooves 11, 13.

[0042]
The groove depths of the circumferential main grooves 11, 13, 15, 17 may be the same as each other or different.

The maximum depths of the chamfers 21a, 23a, 25a, 51a, 53a may be the same as each other or different.
The groove depths of the circumferential shallow grooves 41, 43 may be the same as each other or different.
The maximum widths of the land portion blocks 24, 26 may be the same as each other or different.
The sipes 34, 36 may not be arranged parallel to the lug grooves 33, 35.
The sipes 34, 36 may be respectively connected with the outer circumferential main grooves 11, 13. Furthermore, the sipes 34, 36 may be respectively blocked within the intermediate land portions 23, 25 without connecting with the inner circumferential main grooves 15, 17. The tread pattern 10 may not have the sipes 34, 36.
The sipes 34, 36 may be provided only on one side of the circumferential shallow grooves 41, 43.
The shoulder lug grooves 61, 63 may be respectively connected with the outer circumferential main grooves 11, 13, thereby forming a plurality of land portion blocks in the tire circumferential direction. The tread pattern 10 may not have the shoulder lug grooves 61, 63.
The groove width of the shoulder lug grooves 61, 63 may be equal to or less than the groove width of the lug grooves 31, 33, 35.
The number of circumferential main grooves is not limited to four and may be five or more. In this case, three inner circumferential main grooves can be provided.

[0043]
The tread pattern 10 in the above pneumatic tire 1 has the four circumferential main grooves 11, 13, 15, 17 and the lug grooves 31 and the sipes 32 in the region of the inside land portion 21, and further has the lug grooves 33, 35 and the sipes 34, 36 in the regions of the intermediate land portions 23, 25, whereby the basic wet turning performance and the steering stability on snow required for tire performance are assured.
Furthermore, the lug grooves 33, 35 provided in the respective intermediate land portions 23, 25 are inclined in the same orientation with respect to directions (X1 direction and X2 direction) different from each other of the tire circumferential direction, and the lug grooves 33, 35 are inclined in an opposite orientation with respect to the tire circumferential direction of the lug grooves 31 provided in the region of the inside land portion 21, and moreover, the lug grooves 33, 35 are bent so that the groove inclination approaches the tire circumferential direction (X1 direction, X2 direction) at the points P, Q where the lug grooves 33, 35 respectively intersect the circumferential shallow grooves 41, 43, whereby wet turning performance and steering stability on snow are improved.
Furthermore, when the configuration of the shoulder lug grooves 61, 63 is added to the configuration of the lug grooves 31, 33, 35, the tread pattern has grooves with various orientations and inclination angles, whereby wet turning performance and steering stability on snow are further improved.
Furthermore, the regions of the intermediate land portions 23, 25 are respectively provided with the circumferential shallow grooves 41, 43 having a groove depth less than the groove depth of the circumferential main grooves 11, 13, 15, 17, whereby abrasion resistance is assured.

[0044]
The sipes 34, 36 are provided respectively in the regions of the intermediate land portions 23, 25 and are blocked within the intermediate land portions 23, 25 without connecting with the inner circumferential main grooves 15, 17, whereby abrasion resistance on dry road surfaces is assured.
The sipes 34, 36 have the three-dimensional shape in the regions on the inner side in the tire width direction of the circumferential shallow grooves 41, 43, whereby block rigidity during braking and driving is improved.

[0045]
The formation of the continuous land portions extending continuously in the tire circumferential direction in the regions of the shoulder land portions 51, 53 allows a high block rigidity of the shoulder land portions 51, 53 to be assured and allows abrasion resistance on dry road surfaces to be improved.
Furthermore, a reduction in block rigidity of the shoulder land portions 51, is prevented and abrasion resistance on dry road surfaces is assured.
The maximum groove width of the shoulder lug grooves 61, 63 is greater than the groove width of the lug grooves 31, 33, 35, whereby wet turning performance and steering stability on snow are improved.
Chamfers are provided on some of the edge portions in the tire width direction of the inside land portion 21 and the intermediate land portions 23, 25, whereby the edge amounts are increased, and wet turning performance and steering stability on snow are improved.

[0046]
(Other forms of tread pattern) The sipes 34, 36 may not be provided in parallel with the lug grooves 33, 35. The sipes 34, 36 may be connected with the outer circumferential main grooves 11, 13. Further, the sipes 34, 36 may be blocked within the intermediate land portions without connecting with the inner circumferential main grooves 15, 17. The tread pattern 10 may not include the sipes 34, 36.
The sipes 34, 36 may have a two-dimensional shape on the inner side of the circumferential shallow grooves 41, 43 and a three-dimensional shape on the outer side of the circumferential shallow grooves 41, 43. Alternatively, on both sides of the inner side and the outer side, the sipes 34, 36 may have a two-dimensional shape or three-dimensional shape. The sipes 34, 36 may have a combination of the two-dimensional shape and a three-dimensional shape on at least one of the two sides. One of the sipes 34, 36 may be provided on one side of the two sides against the provided two circumferential shallow grooves 41, 43.
The shoulder lug grooves 61, 63 may be connected with the outer circumferential main grooves 11, 13 to form a plurality of land portion blocks arranged in the tire circumferential direction. The tread pattern 10 may not include the shoulder lug grooves 61, 63. The groove width of the shoulder lug grooves 61, 63 may be not greater than the groove width of the lug grooves 31, 33, 35.
The number of the circumferential groves provided on the tread surface is not limited to four. The number may be five or more. In this case, the tread pattern may include three or more of the inner circumferential main grooves.

[0047]
(EXAMPLE) Test tires were manufactured to study the effects of the tread pattern 10 of the tire 1 of the present invention.
The tire size was P265/70R17 113T. Tires with a rim size of 17x7.5J
were manufactured provided with the tread patterns according to the specifications described in the following Tables 1 and 2. A front-engine, front-drive (FF) vehicle with an engine displacement of 2 liters was used as a test vehicle for studying tire performance. The inner pressure of all of the front wheels and the rear wheels was set to 230 kPa.
Wet turning performance, steering stability on snow, and abrasion resistance were evaluated for tire performance of the test tires as described below.

[0048]
The test vehicle was driven for 5 laps at a limited speed on an R30 (radius 30 m) turning course of a wet road surface of an outdoor tire testing facility having a film of water with a depth of 1 mm in, and the average lateral acceleration at this time was measured for evaluating the wet turning performance. The evaluation was performed by expressing the inverse of the measured values as an index and taking the inverse of the measured value of the tire of the Conventional Example 1 as 100. A larger index signifies a correspondingly superior wet turning performance.
For the steering stability on snow, the measurement was made in the same way as the measurement of the wet turning performance, except for the road surface being changed from a wet road surface having a film of water with a depth of 1 mm to a snow-covered road surface. The evaluation was performed by expressing the inverse of the measured values as an index and taking the inverse of the measured value of the tire of the Conventional Example 1 as 100. A larger index signifies a correspondingly superior steering stability on snow.
The abrasion resistance was evaluated by measuring the amount of abrasion after the test vehicle was driven for 2000 km on public roads. The evaluation was carried out by taking the inverse of the measurement values and expressing the inverse of the measurement values of the tire of the Conventional Example 1 as 100. A larger index signifies a correspondingly superior abrasion resistance.

[0049]
The respective evaluation results are described in Tables 1 and 2.
Note that "not parallel" signifies that the direction in which the sipes extend is in the opposite orientation with respect to the tire width direction to the direction in which the lug grooves extend inside the region of the same intermediate land portion, and "parallel" signifies that the direction in which the sipes extend is in the same orientation with respect to the tire width direction as the direction in which the lug grooves extend inside the region of the same intermediate land portion, in Tables 1 and 2. Furthermore, the groove depth of the circumferential shallow grooves signifies a percentage (%) with respect to the groove depth of the circumferential main grooves. Whether the shoulder lug grooves are blocked or not indicates that the shoulder lug grooves 61, 63 are blocked part way through without connecting with the outer circumferential main grooves 11, 13, or indicates that the shoulder lug grooves 61, 63 are connected with the outer circumferential main grooves 11, 13. The sipes in the intermediate land portions all had the two-dimensional shape in the Working Example 3.

[0050]
[Table 1]
Working Working Conventional Working Working Working Example Example Example 1 Example 1 Example 2 Example 3 Presence or absence of lug grooves in inside land portion, Present, Present, Present, Present, Present, inclination 70 70 Absent 70 degrees 70 degrees 70 degrees angle of lug degrees degrees mm 5 mm 5 mm grooves, 5 mm 5 mm maximum groove width thereof ' Presence or absence of bends in lug grooves in Bend Bend intermediate Bend Bend Bend 70 70 No bend land 70 degrees 70 degrees 70 degrees degrees degrees 70 degrees portions, 45 degrees 45 degrees 45 degrees 45 45 5 mm inclination 5 mm 5 mm 5 mm degrees degrees angle of lug 5 mm 5 mm grooves, maximum groove width thereof Presence or absence of circumferent ial shallow Present, Present, Present, Present, Present, grooves, Absent 30% 30% 30% 30% 30%
groove depth thereof Sipes in intermediate Not land portion Not parallel Parallel Parallel Parallel Parallel parallel (parallel, not parallel) Presence or absence of sipes with three-dimen sional shape Absent Present Present Absent Present Present in intermediate land portions Inclination angle of shoulder lug grooves, 70 degrees 85 degrees 85 degrees 85 degrees degrees degrees maximum 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm groove width thereof Presence or absence of blocking in Absent Present Present Present Absent Present shoulder lug grooves Presence or Absent Present Present Present Present Absent absence of chamfers in land portions Steering stability on 100 104 104 106 106 102 snow Wet turning performance Abrasion resistance

[0051]
[Table 2]
Comparative Comparative Comparative Example 1 Example 2 Example 3 Presence or absence of lug grooves in inside land portion, Present, Present, Present, inclination angle of 70 degrees 70 degrees 70 degrees lug grooves, 5 mm 5 mm 5 mm maximum groove width thereof Presence or absence of bends in lug grooves in Bend Bend intermediate land 70 degrees 70 degrees No bend portions, inclination 45 degrees 45 degrees 70 degrees mm angle of lug grooves, 5 mm 5 mm maximum groove width thereof Presence or absence of circumferential Present, Present, shallow grooves, Absent 100% 60%
groove depth thereof Sipes in intermediate land portions Parallel Parallel Parallel (parallel, not parallel) Presence or absence of sipes with three-dimensional Present Present Present shape in intermediate land portions Inclination angle of shoulder lug 85 degrees 85 degrees 85 degrees grooves, maximum 5 mm 5 mm 5 mm groove width thereof Presence or absence of blocking in Present Present Present shoulder lug grooves Presence or absence of chamfers in land Present Present Present portions Steering stability on snow Wet turning performance Abrasion resistance 100 95 95

[0052]
As can be seen in Table 1 and Table 2, when the lug grooves were bent in the region of the intermediate land portions and the groove depth of the circumferential shallow grooves was less than the groove depth of the circumferential main grooves (Working Examples 1 to 5), the balance between abrasion resistance on dry road surfaces, and wet turning performance and steering stability on snow was more superior than when the above was not true (Comparative Examples 1 to 3). That is, abrasion resistance on dry road surfaces was maintained (index of 100 or more), and wet turning performance and steering stability on snow were superior (index of 102 or more).
In particular, the tires of the Working Examples 1 to 5 in which the groove depth of the circumferential shallow grooves was 30% of the groove depth of the circumferential main grooves demonstrated a balance between steering stability on snow, wet turning performance, and abrasion resistance more superior than that of the tire of the Comparative Example 2 in which the lug grooves were bent in the region of the intermediate land portions while the groove depth of the circumferential shallow grooves was the same (100%) as the groove depth of the circumferential main grooves.

[0053]
The pneumatic tire of the present invention was described in detail above.
However, it should be understood that the present invention is not limited to the above embodiments, but may be improved or modified in various ways so long as these improvements or modifications remain within the scope of the present invention.
REFERENCE NUMBER

[0054]
1 Pneumatic Tire 2 Tread portion Tread pattern 11, 13 Outer circumferential main grooves 15, 17 Inner circumferential main grooves 21 Inside land portion 21a, 23a, 25a, 51a, 53a, Chamfer 23, 25 Intermediate land portions 22, 24, 26 Land portion block 31, 33, 35 Lug grooves 31w, 33w, 35w Lug groove maximum groove width 34, 36 Sipes 41, 43 Circumferential shallow grooves 51, 53 Shoulder land portions 61, 63 Shoulder lug grooves 61w, 62w Shoulder lug groove maximum groove width Oml, 0m2 Lug groove inclination CL Center line P, Q Lug groove and circumferential shallow groove intersecting position X1 First direction in tire circumferential direction X2 Second direction in tire circumferential direction

Claims

CLAIMS:

1. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of a first intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of a second intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves;
an orientation of the groove inclination of the first lug grooves with respect to the first direction in an outer region in the tire width direction of the first intermediate land portion being identical to an orientation of the groove inclination of the first lug grooves with respect to the first direction in an inner region in the tire width direction of the first intermediate land portion, while an inclination angle of the first lug grooves with respect to the first direction in the outer region is larger than an inclination angle of the first lug grooves with respect to the first direction in the inner region, when the first lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction, an orientation of the groove inclination with respect to the second direction of the second lug grooves in an outer region in the tire width direction of the second intermediate land portion being identical to an orientation of the groove inclination of the second lug grooves with respect to the second direction in an inner region in the tire width direction of the second intermediate land portion, while an inclination angle of the second lug grooves with respect to the second direction in the outer region is larger than an inclination angle of the second lug grooves with respect to the second direction in the inner region, when the second lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction; and lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction.

2. The pneumatic tire according to claim 1, wherein the respective regions of the intermediate land portions have sipes extending so as to be parallel to the lug grooves provided in the respective regions of the intermediate land portions, and the sipes are blocked within the intermediate land portions without connecting with the inner circumferential main grooves.

3. The pneumatic tire according to claim 2, wherein the sipes extend in a zigzag manner while deflecting in a direction orthogonal to an extension direction of the sipes and extend in a zigzag manner while deflecting in a direction orthogonal to a sipe depth direction of the sipes from a tread surface toward a bottom portion of the sipes in a region on the inner side of the circumferential shallow grooves.

4. The pneumatic tire according to claim 2 or 3, wherein the sipes extend in a linear manner in a region on the outer side of the circumferential shallow grooves in the tire width direction, and extend in a planar manner in a depth direction of the sipes from a tread surface toward a bottom portion of the sipes.

5. The pneumatic tire according to any one of claims 1 to 4, further comprising shoulder land portions provided in regions on the outer side of the circumferential main groove group in the tire width direction;
regions of the shoulder land portions having shoulder lug grooves provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, the shoulder lug grooves being blocked part way through without connecting with the outer circumferential main grooves, whereby the shoulder land portions forming continuous land portions extending continuously in the tire circumferential direction.

6. The pneumatic tire according to any one of claims 1 to 5, further comprising shoulder land portions provided in regions on the outer side of the circumferential main groove group in the tire width direction;
regions of the shoulder land portions having shoulder lug grooves provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves;
a maximum groove width of the shoulder lug grooves being greater than a maximum groove width of the lug grooves provided in the region of the inside land portion and in the regions of the intermediate land portions.

7. The pneumatic tire according to claim 6, wherein the shoulder land portions have shoulder sipes provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, and the shoulder sipes include a first portion extending in a linear manner in an extension direction of the shoulder sipes and extending in a planar manner in a sipe depth direction of the shoulder sipes from a tread surface toward a bottom portion of the shoulder sipes, and a second portion extending in a zigzag manner while deflecting in a direction orthogonal to the extension direction of the shoulder sipes and extending in a zigzag manner while deflecting in a direction orthogonal to a sipe depth direction of the shoulder sipes from a tread surface toward the bottom portion, and the shoulder sipes change from the first portion to the second portion while advancing from the outer side in the tire width direction toward the outer circumferential main grooves and then end.

8. The pneumatic tire according to any one of claims 1 to 7, wherein portions of edge portions coming into contact with the circumferential main grooves in the inside land portion and the intermediate land portions are provided with a chamfer.

9. The pneumatic tire according to any one of claims 1 to 8, wherein a width of a land portion in a region on the inner side of the circumferential shallow grooves in the tire width direction is greater than a width of a land portion in a region on the outer side of the circumferential shallow grooves in the tire width direction in the intermediate land portions.

10. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves; and lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction, wherein the respective regions of the intermediate land portions have sipes extending so as to be parallel to the lug grooves provided in the respective regions of the intermediate land portions, and the sipes are blocked within the intermediate land portions without connecting with the inner circumferential main grooves, and wherein the sipes extend in a linear manner in a region on the outer side of the circumferential shallow grooves in the tire width direction, and extend in a planar manner in a depth direction of the sipes from a tread surface toward a bottom portion of the sipes.

11. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves;
lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction; and shoulder land portions provided in regions on the outer side of the circumferential main groove group in the tire width direction;
regions of the shoulder land portions having shoulder lug grooves provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, the shoulder lug grooves being blocked part way through without connecting with the outer circumferential main grooves, whereby the shoulder land portions forming continuous land portions extending continuously in the tire circumferential direction.

12. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves;
lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction; and shoulder land portions provided in regions on the outer side of the circumferential main groove group in the tire width direction;
regions of the shoulder land portions having shoulder lug grooves provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves;
a maximum groove width of the shoulder lug grooves being greater than a maximum groove width of the lug grooves provided in the region of the inside land portion and in the regions of the intermediate land portions, wherein the shoulder land portions have shoulder sipes provided therein, extending from the outer side in the tire width direction toward the outer circumferential main grooves, and the shoulder sipes include a first portion extending in a linear manner in an extension direction of the shoulder sipes and extending in a planar manner in a sipe depth direction of the shoulder sipes from a tread surface toward a bottom portion of the shoulder sipes, and a second portion extending in a zigzag manner while deflecting in a direction orthogonal to the extension direction of the shoulder sipes and extending in a zigzag manner while deflecting in a direction orthogonal to a sipe depth direction of the shoulder sipes from a tread surface toward the bottom portion, and the shoulder sipes change from the first portion to the second portion while advancing from the outer side in the tire width direction toward the outer circumferential main grooves and then end.

13. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves; and lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction, wherein portions of edge portions coming into contact with the circumferential main grooves in the inside land portion and the intermediate land portions are provided with a chamfer.

14. A pneumatic tires comprising:
a bead;
a tread portion having a tread pattern;
a side wall disposed between the tread portion and the bead;
a carcass layer disposed at least partly within the side wall; and a belt layer disposed in a region of the tread portion;
the tread pattern including:
a circumferential main groove group having four circumferential main grooves extending parallel to the tire circumferential direction, the four circumferential main grooves including two outer circumferential main grooves and two inner circumferential main grooves interposed by the outer circumferential main grooves with a tire center line passing between the inner circumferential main grooves;
a plurality of lug grooves transecting a region of an inside land portion partitioned by the two inner circumferential main grooves and through which the tire center line passes, and regions of two intermediate land portions each partitioned by one of the outer circumferential main grooves and one of the inner circumferential main grooves, to form a plurality of land portion blocks in the inside land portion and in the intermediate land portions; and circumferential shallow grooves that are provided in the respective regions of the intermediate land portions, that extend in the tire circumferential direction, and that have a groove depth that is less than a groove depth of the circumferential main grooves;
an orientation of a groove inclination with respect to a first direction of the tire circumferential direction of lug grooves provided in a region of one intermediate land portion of the two intermediate land portions being identical to an orientation of a groove inclination with respect to a second direction that is opposite to the first direction of the tire circumferential direction of second lug grooves provided in a region of another intermediate land portion of the two intermediate land portions when the lug grooves provided in each of the two intermediate land portions advances from the outer side in the tire width direction to the inner side in the tire width direction, and the lug grooves provided in the respective regions of the intermediate land portions having bent portions, the bent portions being bent so that the groove inclination approaches the tire circumferential direction at positions of intersection with the circumferential shallow grooves; and lug grooves that are provided in the inside land portion extending in an orientation of a groove inclination that is different with respect to the tire circumferential direction from lug grooves provided in the respective regions of the intermediate land portions, when the lug grooves advance from the outer side in the tire width direction to the inner side in the tire width direction, wherein a width of a land portion in a region on the inner side of the circumferential shallow grooves in the tire width direction is greater than a width of a land portion in a region on the outer-side of the circumferential shallow grooves in the tire width direction in the intermediate land portions.