CN211222917U - Sand and mud ground dual-purpose pneumatic tyre for cross-country motorcycle - Google Patents

Abstract

The utility model discloses dual-purpose cross country motorcycle pneumatic tire in sand and mud ground relates to a pneumatic tire. The tire tread of the tire is composed of a central pattern block, a middle pattern block and a shoulder pattern block. The central pattern block is arranged on the central line of the tread, the central pattern block and the middle pattern block extend downwards from the central line of the tread to the outside in sequence and are symmetrically designed in a convex arc shape relative to the central line of the tread, and the tire shoulder pattern block is symmetrically arranged at the tire shoulder relative to the central line of the tread and is arranged in a staggered mode with the middle pattern block at the circumferential direction. The upper part of the rear ground-contacting side of the central pattern block or the middle pattern block is a sawtooth part, and the lower part is a concave part. The traction and sand and mud discharging performances of the sand and mud land on two off-road roads can be considered.

Description

Sand and mud ground dual-purpose pneumatic tyre for cross-country motorcycle

Technical Field

The utility model relates to a pneumatic tire. The tread pattern structure is optimally designed, and the traction and sand and mud discharge performance of the sand and mud dual-purpose off-road pavement can be considered.

Background

With the continuous development of the cross-country motorcycle race, the used terrains are more and more diversified, the terrains cover from hard road surfaces (such as rocks, broken stones, hardened red soil and the like) to soft road surfaces (such as sand, mud and the like), the conventional cross-country motorcycle tire generally adopts a single-use terrains corresponding to a single tire, and is converted into a tire corresponding to a plurality of different-use terrains, aiming at the motorcycle tire for the sand and mud dual-purpose cross-country road, a blocky pattern design is adopted on the tire tread in the past (shown in figure 1), central pattern blocks 10 ' and middle pattern blocks 20 ' are symmetrically arranged side by side in the axial direction of the tire on both sides of the center line CL of the tire tread, and shoulder pattern blocks 30 ' are arranged between two rows of central pattern blocks 10 ' and the middle pattern blocks 20 ' which are adjacent in the circumferential direction at; the central pattern blocks 10 ', the middle pattern blocks 20 ' and the tire shoulder pattern blocks 30 ' in each row are arranged at intervals along the circumferential direction at a certain distance, and the pattern blocks can cut into a muddy road surface to improve the traction performance of the muddy road surface.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a sand and mud ground dual-purpose cross country motorcycle pneumatic tire. The tire tread pattern structure is optimally designed, and the traction and sand and mud discharge performance of running on two off-road pavements of sand and mud land can be taken into consideration.

The technical scheme of the utility model is that: a sand-mud ground dual-purpose cross-country motorcycle pneumatic tire is characterized in that a tire tread consists of a central pattern block, a middle pattern block and a tire shoulder pattern block; the method is characterized in that: the central pattern block is arranged on the central line of the tread, the central pattern block and the middle pattern block extend downwards from the central line of the tread to the outside in sequence and are symmetrically designed in a convex arc shape relative to the central line of the tread, and the tire shoulder pattern block is symmetrically arranged at the tire shoulder relative to the central line of the tread and is arranged in a staggered mode with the middle pattern block at the circumferential direction.

So set up, central pattern piece and the middle pattern block of the left and right sides combine to form a convex arc, can effectively dial out and get rid of earth, can compromise the traction and the sediment removal performance that two kinds of cross-country road surfaces go on sand and mud ground.

In a preferred embodiment: the central pattern block is a transverse long polygonal pattern block with at least one convex part on the ground contact side.

The convex part design of the first grounding side of the central pattern block is utilized, the pattern edge component of the central pattern block can be improved, and the traction performance of the tire when the tire runs on a mud road surface is improved.

In particular: the middle pattern block is a transverse long polygonal pattern block with a convex part and a concave part on the ground contact side, and the concave part is arranged on the axial outer side.

By utilizing the concave-convex part combination design of the first grounding side of the middle pattern block, the pattern edge component of the middle pattern block can be improved, and the traction performance of the tire when the tire runs on a muddy road surface is further improved.

In a preferred embodiment: the upper part of the rear grounding side of the central pattern block is a sawtooth part provided with a tooth groove, and the lower part of the rear grounding side of the central pattern block is a concave part.

The upper part of the rear grounding side of the central pattern block adopts a sawtooth part design, so that the edge effect of the central pattern block can be improved, the traction performance of sand is improved, and the lower part adopts an arc concave part design, so that sand can be gathered, and the sand discharging performance is improved.

And further: the sawteeth on two sides of the sawteeth part of the rear grounding side of the central pattern block are long sawteeth, each middle sawtooth is a short sawtooth, the circumferential length of each long sawtooth is greater than that of each middle short sawtooth, and the concave part of the rear grounding side of the central pattern block is transited to the groove bottom by adopting an arc surface.

The rear grounding side structural form of the combination of the circumferential fall sawtooth part and the arc surface concave part is beneficial to gathering sand in the rear grounding side wall of the central pattern block, and the sand discharge performance is improved.

In a preferred embodiment: the upper part of the rear grounding side of the middle pattern block is a sawtooth part provided with a tooth groove, and the lower part of the rear grounding side of the middle pattern block is a concave part.

The upper part of the rear grounding side of the middle pattern block adopts a fall sawtooth part design, so that the edge effect of the middle pattern block can be improved, the traction performance of the sand is improved, and the lower part adopts an arc concave part design, so that sand can be gathered, and the sand discharging performance is improved.

And further: the sawteeth on two sides of the middle pattern block rear grounding side sawteeth part are long sawteeth, each middle sawtooth is a short sawtooth, the circumferential length of each long sawtooth is greater than that of each middle short sawtooth, and the concave part of the middle pattern block rear grounding side is transited to the groove bottom by adopting an arc surface.

The rear grounding side structural form of the combination of the circumferential fall sawtooth part and the arc surface concave part is beneficial to gathering sand in the rear grounding side wall of the middle pattern block, and the sand discharge performance is improved.

After the technology of the utility model is used, the specification of motorcycle tyre series national standard 110/90-1962M TT for the rear wheel of the off-road motorcycle is selected, and we only do four kinds of test tyres respectively, wherein:

the first test tire was of the prior art as shown in fig. 1;

the first grounding side of the central pattern block of the second test tire is provided with a convex part, the first grounding side of the middle pattern block is not provided with the convex part and the concave part, and the rear grounding sides of the central pattern block and the middle pattern block are not provided with the sawtooth part and the concave part; the ratio of the axial length to the circumferential length of the central pattern blocks is 3.0, and the circumferential distance between the top point of the first grounding side convex part of the first central pattern block and the top point of the axial outer side of the first central pattern block is 3.5 mm; the circumferential distance from the top point of the two convex parts on the first grounding side of the second central pattern block to the top point of the axial outer side of the second central pattern block is 5mm, and the ratio of the circumferential distance from the concave point between the two convex parts to the top point of the convex parts to the circumferential distance from the top point of the two convex parts on the first grounding side of the second central pattern block to the top point of the axial outer side of the second central pattern block is 0.5. The ratio of the axially extending length to the circumferentially extending width of the intermediate block is 2.75.

The third test tire is that on the basis of various parameters of the second test tire, convex parts and concave parts are additionally arranged on the first grounding side of the middle pattern block, and the rear grounding sides of the middle pattern block and the middle pattern block still have no sawtooth parts and concave parts; the included angle between the inner lateral edge of the first grounding side convex part of the middle pattern block and the axial direction is 16 degrees, the circumferential distance between the concave point of the concave part and the peak of the convex part is 49 percent of the extension width of the middle pattern block, the outer peripheral edge of the middle pattern block is obliquely arranged towards the inner side of the axial direction, and the included angle between the outer peripheral edge of the middle pattern block and the circumferential direction is 45 degrees.

The third test tire is characterized in that on the basis of various parameters of the third test tire, sawteeth and concave parts are added on the rear ground-contacting side of the central pattern block and the middle pattern block; the circumferential width of the sawtooth part is 16% of the circumferential length of the pattern block, the circumferential fall width of the short sawteeth in the middle of the sawtooth part and the long sawteeth on the two side edges is 16% of the circumferential length of the pattern block, the circumferential rear side width of each independent sawtooth is 1.0mm, and the height of each sawtooth from the bottom surface to the surface of the pattern block is 65% of the height of the pattern block.

Each test tire was mounted on a 2.50X19 rim, and an internal pressure of 91kPa was applied, and mounted on a motorcycle with an air displacement of 450CC, and traction and sand and mud removal performance were evaluated while running on a sandy road surface, and the vehicle test performance was compared by sensory evaluation by the driver with the first test tire as a reference and each index being 100%.

The second test tire had a mud traction index of 105%, a mud drainage index of 100%, a sand traction index of 100%, and a sand drainage index of 100%.

The third test tire had a mud traction index of 105%, a mud drainage index of 105%, a sand traction index of 100%, and a sand drainage index of 100%.

The fourth test tire had a mud traction index of 105%, a mud drainage index of 105%, a sand traction index of 105%, and a sand drainage index of 105%.

The utility model discloses dual-purpose cross country motorcycle pneumatic tire in sand and mud ground improves the traction and the sediment removal mud performance that two kinds of cross country road surfaces in sand and mud ground went through tread decorative pattern structural optimization design. The experiment proves that the utility model discloses the traction of husky mud ground dual-purpose cross country motorcycle pneumatic tire is excellent with row mud, husky performance than prior art really, and the intensity of decorative pattern piece is good moreover, and durability is good.

Drawings

FIG. 1 is a schematic view of a tire tread pattern of a conventional pneumatic tire for a motorcycle used on both sand and mud fields;

FIG. 2 is a schematic view of a tire tread pattern of a preferred embodiment of the pneumatic tire for a sand and mud dual-purpose dirtbike of the present invention;

FIG. 3 is a schematic perspective view of a first central laterally elongated polygonal block of the tread of the tire of the embodiment of FIG. 2;

FIG. 4 is a schematic structural view of the first central laterally long polygonal block of FIG. 3;

FIG. 5 is a cross-sectional view taken along line A-A' of FIG. 4;

FIG. 6 is a schematic perspective view of a second central laterally elongated polygonal block of the tread of the tire of the embodiment of FIG. 2;

FIG. 7 is a schematic structural view of the second central laterally long polygonal block of FIG. 6;

FIG. 8 is a sectional view taken along line G-G' of FIG. 7;

FIG. 9 is a schematic perspective view of the middle block of the tire tread of the embodiment of FIG. 2;

FIG. 10 is a schematic structural view of the middle block of FIG. 9;

fig. 11 is a sectional view taken along line P-P' in fig. 10.

Detailed Description

The utility model discloses dual-purpose cross country motorcycle pneumatic tire's in sand and mud ground tire tread decorative pattern structure please refer to fig. 2. In the figure, the transverse direction is the axial direction of the tire, the longitudinal direction is the circumferential direction of the tire, CL is the central line of the tread, the arrow points to the running direction of the tire, one side close to the central line of the tread is the inner side, one side far away from the central line of the tread is the outer side, the same direction with the running direction is the first grounding side, and the side far away from the running direction is the second grounding side.

As shown in FIG. 2, the dual-purpose pneumatic tire for off-road motorcycles used in sandy mud land of the present invention is designed by optimizing the tread pattern structure, the tire tread 1 is composed of a central pattern block 10, a middle pattern block 20 and a shoulder pattern block 30, each pattern block is arranged at a certain distance along the circumferential direction at intervals, wherein the central pattern block 10 and the middle pattern block 20 extend downward from the tread center line in sequence and are arranged in a convex arc line approximately symmetrically with respect to the tire tread center line CL, the shoulder pattern block 30 is arranged at the tire shoulder and arranged in a staggered manner with the middle pattern block 20 at intervals in the circumferential direction, the central pattern block 10 is arranged on the tread center line, and is a transverse long polygonal pattern block with at least one convex part at the ground contact side (the central pattern block 10 of the present embodiment has two structural forms, the first is a first central transverse long polygonal pattern block 11 with one convex part (hereinafter referred to as the, the second type is a second central laterally long polygonal block 12 with two convex portions (hereinafter referred to as second central block 12) which are alternately arranged with a spacing therebetween. The middle pattern block 20 is arranged on the axial outer side of the central pattern block 10, and is a transverse long polygonal pattern block with a convex part and a concave part on the first grounding side, and the concave part is arranged on the axial outer side, so that the central pattern block 10 and the middle pattern blocks 20 on the left side and the right side are combined to form a convex arc shape, sand and mud can be effectively removed, meanwhile, concave-convex parts on the first grounding side of the central pattern block 10 and the middle pattern blocks 20 are combined to design, pattern edge components can be improved, and the traction performance of the tire in the driving process of a sand and mud ground road surface is improved.

The structure of the first center block 11, please refer to fig. 3, 4 and 5: the convex portion apex B of the first center block 11 is located on the tire tread center line CL. The ratio of the axial length L1 to the circumferential length L2 of the first center block 11 is 2.5-4.5. If the ratio is set too large, the first central pattern blocks 11 are too large to effectively cut into the soil and improve the traction performance; if the ratio is set too small, the first center block 11 is too small to collect soil and affect soil removal performance. The circumferential distance L5 from the apex B of the leading ground-contacting side protrusion of the first center block 11 to the apex C of the axially outer side of the first center block 11 is set to 1.5mm to 5 mm. If the circumferential distance L5 is set too small, the first center block 11 is less likely to cut into the soil and the traction performance of the mud road is improved; if the circumferential distance L5 is set too large, the first center block 11 cannot effectively collect dirt and the dirt discharge performance is affected.

The rear ground-contacting side of the first central pattern block 11 adopts a drop layer combination design of a sawtooth part 11a, a flat part 11b and a concave part 11c, the upper part of the rear ground-contacting side is the sawtooth part 11a with a tooth slot, and the lower part is the concave part 11 c; the gullet cross section of the serration 11a may be rectangular or trapezoidal or triangular or circular arc. The indented portion 11a of the rear ground-contacting side of the first center block 11 is designed by a combination of the middle short indented portion 11a1 and the both side length indented portions 11a 2. So as to gather sand in the rear grounding side wall of the pattern block and improve the sand discharge performance. The concave part 11c adopts an arc surface to transit to the bottom of the ditch, so the design of the fall sawtooth part 11a is adopted on the upper part of the back grounding side of the pattern block, the edge effect of the pattern block can be improved, the traction performance of the sand ground is improved, and the design of the arc concave part 11c is adopted on the lower part, sand can be gathered, and the sand discharge performance is improved.

The circumferential width L11 of the indented portion 11a of the first center block 11 is set to 10% -25% of the circumferential length L2 of the first center block 11; if the circumferential width L11 of the serration 11a is too small, the first center block 11 cannot effectively cut into the sand road surface, improving traction performance; if the circumferential width L11 of the serration 11a is too large, the strength of the block is too weak, and root breaking is likely to occur. The circumferential step width W1 between the short serration 11a1 in the middle of the serration 11a and the long serration 11a2 on both sides is set to 10% to 25% of the circumferential length L2 of the first center block 11. If the circumferential drop width W1 is too small, the first central pattern block 11 cannot effectively collect sand, which affects the sand discharge performance; if the circumferential drop width W1 is too large, the strength of the block is too weak, and root breaking is likely to occur.

The circumferential rear side width W2 of each individual serration of the serration 11a of the first center block 11 is set to 1.0mm-2.0 mm. If the circumferential rear width W2 of each individual serration of the serration part 11a is too small, the strength of the serration is too weak, and the serration phenomenon is liable to occur, and if the circumferential rear width W2 of each individual serration is too large, the first center block 11 cannot effectively cut into the sand, affecting the sand discharge performance. The height H1 of each serration from the bottom surface to the surface of the block is set to 30% -70% of the height H of the block. If the height H1 of each serration from the bottom surface to the block surface is set too small, the first center block 11 cannot cut into the sand to affect the sand discharge performance, and if the height H1 of each serration from the bottom surface to the block surface is set too large, the strength of the serration portion is too weak, and the serration phenomenon is likely to occur.

The structure of the second center block 12, please refer to fig. 6, 7 and 8: the apexes D of the two convex portions of the second center block 12 are symmetrically distributed on both sides of the tire tread center line CL. The ratio of the axial length L1 'to the circumferential length L2' of the second center block 12 is 2.5-4.5. If the ratio is set too large, the second central pattern blocks 12 are too large to cut into the soil effectively and improve traction performance; if the ratio is set too small, the second center block 12 is too small to collect soil and affect soil removal performance. The circumferential distance L6 between the apexes D of the two convex portions on the first ground contact side of the second center block 12 and the apexes E on the axial outer sides of the second center block 12 is set to 1.5mm to 5mm, which ensures that the blocks cut into the soil and further improves the traction performance of the soil. If the circumferential distance L6 is set too small, the second center block 12 is less likely to cut into the soil and affect the traction performance of the mud road; if this circumferential distance L6 is set too large, the second center block 12 will not be able to effectively collect dirt, which affects dirt removal performance. The ratio of the circumferential distance L7 from the apex D of the convex portion to the concave point F between the two convex portions to the circumferential distance L6 from the apex D of the two convex portions on the first ground contact side of the second center block 12 to the apex E of the axially outer side of the second center block 12 is 0.5 to 1.0. If the ratio is set too small, the second center blocks 12 are not likely to cut into the soil and affect the traction performance of the mud road, and if the ratio is set too large, the second center blocks 12 cannot effectively collect the soil and affect the soil removal performance.

The rear ground-contacting side of the second central block 12 is also designed by adopting a step level combination of a sawtooth part 12a, a flat part 12b and a concave part 12c, the upper part of the rear ground-contacting side is the sawtooth part 12a with a tooth slot, the lower part of the rear ground-contacting side is the concave part 12c, the cross section of the tooth slot of the sawtooth part 12a can be rectangular, trapezoidal, triangular or circular arc, the sawtooth part 12a of the rear ground-contacting side of the block is designed by combining a middle short sawtooth 12a1 and two side long sawteeth 12a2, and the width of the long sawteeth 12a2 of the two sides is larger than that of the middle short sawteeth 12a 1. So as to gather sand in the rear grounding side wall of the pattern block and improve the sand discharge performance. The concave part 12c adopts a circular arc surface to transit to the bottom of the groove. The upper part of the rear ground-contacting side of the pattern block is designed by adopting a fall sawtoothed part 12a, so that the edge effect of the pattern block can be improved, the traction performance of sand is improved, and the lower part of the pattern block is designed by adopting an arc concave part 12c, so that sand can be gathered, and the sand discharge performance is improved.

The circumferential width L11 'of the indented portion 12a of the second center block 12 is set to 10% -25% of the circumferential length L2' of the second center block 12; the circumferential step width W1 'of the short serration 12a1 at the middle of the serration 12a and the long serration 12a2 at both sides is set to 10% to 25% of the circumferential length L2' of the second center block 12. The circumferential rear side width W2' of each individual serration of the serration portion 12a of the second center block 12 is set to 1.0mm to 2.0 mm. The height H1 'of each serration from the bottom surface to the block surface is set to 30% -70% of the height H' (same as the height H of the first center block 11) of the block. Obviously, the size of the sawteeth 12a of the second central block 12 is set to be identical to the sawteeth 11a of the first central laterally long polygonal block 11, and the function is the same, which will not be described again.

The first center block 11 and the second center block 12 have different numbers of apexes of the first ground contact side protrusions and different heights of edge components, but the pattern edge components are improved, and the mud traction performance is improved. In the present embodiment, they are alternately arranged, or one of them may be arranged, and if two of them are alternately arranged as in the present embodiment, the edge components are more balanced.

The structure of the middle block 20, please refer to fig. 9, 10 and 11: the middle block 20 extends downward toward the outer side of the tire shoulder, and the ground contact side of the middle block has a convex part, the inner lateral edge 21 of the convex part is a straight line, and the outer lateral edge 22 of the convex part is a concave part. The included angle alpha between the inner lateral edge 21 of the middle pattern block 20 firstly connected with the ground lateral protrusion and the axial direction is set to be 5-20 degrees, and the design of the angle can discharge soil to the outer side and improve the soil discharge performance. If the angle is too little, this decorative pattern piece easily blocks earth, makes the difficult discharge of earth, if the angle is too big, its decorative pattern piece can't effectively gather earth and influence the earth of arranging the performance. The circumferential distance L8 from the convex portion apex K to the concave point J of the concave portion is set to 35% -50% of the extended width L4 of the middle block 20; if the concave point J of concave part sets up too little apart from convex part summit K's circumferential distance, its decorative pattern piece easily blocks earth, is difficult for making earth discharge outward, if the concave point J of concave part sets up too big apart from convex part summit K's circumferential distance, can't effectively gather earth and influence row's earth performance. The lateral transverse edge 22 of the middle pattern block 20 is inclined towards the axial inner side, the included angle beta between the lateral transverse edge 22 and the circumferential direction is not less than 15 degrees, and the design can avoid the pattern block from blocking soil and improve the soil discharge performance. So set up and can further cut into earth and make earth discharge to the outside, improve and pull and arrange the soil performance.

The ratio of the axial extension length L3 to the circumferential extension width L4 of the middle block 20 is 2.5-3.5, thereby ensuring the pattern edge component of the transverse edge and improving the traction performance of the mud road. If the ratio is set to be too large, the middle pattern blocks 20 are too large to effectively cut into the soil to improve the traction performance; if the ratio is too small, the middle pattern blocks 20 are too small to effectively collect soil and affect the soil removal performance.

In order to achieve traction performance of sand road running, the rear ground contact side of the middle pattern block 20 is designed by combining the fall layers of the sawtooth part 20a, the flat part 20b and the concave part 20c, the upper part of the rear ground contact side is the sawtooth part 20a with tooth grooves, and the lower part is the concave part 20 c. The sawteeth of the rear ground contact side of the middle block 20 are designed by combining the middle short sawteeth 20a1 and the both side long sawteeth 21a 2. Therefore, sand can be gathered in the rear ground-contacting side of the pattern block, and the sand discharge performance is improved. The gullet cross-section of the serrations 20a may be rectangular or trapezoidal or triangular or circular arc. The concave part 20c adopts an arc surface to transit to the bottom of the ditch, so the design of a fall sawtooth part is adopted on the upper part of the rear grounding side of the middle pattern block 20, the edge effect of the pattern block can be improved, the traction performance of sand ground is improved, the design of the arc concave part is adopted on the lower part, sand can be gathered, and the sand discharge performance is improved.

The circumferential width L11 ″ of the serration 20a of the intermediate block 20 is set to 10% to 25% of the circumferentially extending width L4 of the intermediate block 20; the circumferential step width W1 ″ between the short serration 20a1 in the middle of the serration 20a and the long serration 20a2 on both sides is set to 10% to 25% of the circumferential extension width L4 of the middle block 20. The circumferential rear side width W2 ″ of each individual serration of the serration portion 20a of the middle block 20 is set to 1.0mm to 2.0 mm. The height H1 "of each serration from the bottom surface to the block surface is set to 30% -70% of the height H" (the same as the height H of the first center block 11) of the block. Obviously, the size of the serration 20a of the intermediate block 20 is set to be identical to the serration 11a of the first central laterally long polygonal block 11, and the function is the same, which will not be described again.

The above description is only for the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and all equivalent changes and modifications made by the technical solutions and the contents of the specification of the present invention should fall within the scope covered by the present invention.

Claims (7)

1. A sand-mud ground dual-purpose cross-country motorcycle pneumatic tire is characterized in that a tire tread consists of a central pattern block, a middle pattern block and a tire shoulder pattern block; the method is characterized in that: the central pattern block is arranged on the central line of the tread, the central pattern block and the middle pattern block extend downwards from the central line of the tread to the outside in sequence and are symmetrically designed in a convex arc shape relative to the central line of the tread, and the tire shoulder pattern block is symmetrically arranged at the tire shoulder relative to the central line of the tread and is arranged in a staggered mode with the middle pattern block at the circumferential direction.

2. A pneumatic tire for a dirtbike and sand dual purpose motorcycle according to claim 1, wherein: the central pattern block is a transverse long polygonal pattern block with at least one convex part on the ground contact side.

3. A pneumatic tire for a dirtbike and sand dual purpose motorcycle according to claim 1, wherein: the middle pattern block is a transverse long polygonal pattern block with a convex part and a concave part on the ground contact side, and the concave part is arranged on the axial outer side.

4. A pneumatic tire for a dirtbike or dirtbike as set forth in claim 1, 2 or 3, characterized in that: the upper part of the rear grounding side of the central pattern block is a sawtooth part provided with a tooth groove, and the lower part of the rear grounding side of the central pattern block is a concave part.

5. A pneumatic tire for a sand and mud hybrid electric vehicle according to claim 4, wherein: the sawteeth on two sides of the sawteeth part of the rear grounding side of the central pattern block are long sawteeth, each middle sawtooth is a short sawtooth, the circumferential length of each long sawtooth is greater than that of each middle short sawtooth, and the concave part of the rear grounding side of the central pattern block is transited to the groove bottom by adopting an arc surface.

6. A pneumatic tire for a dirtbike or dirtbike as set forth in claim 1, 2 or 3, characterized in that: the upper part of the rear grounding side of the middle pattern block is a sawtooth part provided with a tooth groove, and the lower part of the rear grounding side of the middle pattern block is a concave part.

7. A pneumatic tire for a sand and mud hybrid electric vehicle according to claim 6, wherein: the sawteeth on two sides of the middle pattern block rear grounding side sawteeth part are long sawteeth, each middle sawtooth is a short sawtooth, the circumferential length of each long sawtooth is greater than that of each middle short sawtooth, and the concave part of the middle pattern block rear grounding side is transited to the groove bottom by adopting an arc surface.

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