JP5060973B2 - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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Publication number
JP5060973B2
JP5060973B2 JP2008009061A JP2008009061A JP5060973B2 JP 5060973 B2 JP5060973 B2 JP 5060973B2 JP 2008009061 A JP2008009061 A JP 2008009061A JP 2008009061 A JP2008009061 A JP 2008009061A JP 5060973 B2 JP5060973 B2 JP 5060973B2
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width direction
sipe
tire
circumferential direction
tire circumferential
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JP2009166762A (en
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修平 武藤
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Bridgestone Corp
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Bridgestone Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1272—Width of the sipe
    • B60C11/1281—Width of the sipe different within the same sipe, i.e. enlarged width portion at sipe bottom or along its length

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Description

本発明は、氷雪上性能の向上を図りつつ、ブロック耐久性を維持することができる重荷重用空気入りタイヤ等の空気入りタイヤに関する。   The present invention relates to a pneumatic tire such as a heavy duty pneumatic tire capable of maintaining block durability while improving performance on snow and snow.

重荷重用空気入りタイヤ等の空気入りタイヤについては氷雪上性能等の向上を図るために種々の開発がなされており、先行技術として特許文献１に示すものがあり、先行技術に係る空気入りタイヤの特徴部分の構成は次のようになる。   Various developments have been made on pneumatic tires such as heavy-duty pneumatic tires in order to improve performance on snow and snow, and there is one disclosed in Patent Document 1 as a prior art. The structure of the characteristic part is as follows.

即ち、先行技術に係る空気入りタイヤにおけるトレッド部には、タイヤ周方向へ延びた複数本の主溝が設けられており、複数本の主溝及びトレッド端によって、タイヤ周方向へ延びた複数の陸部列（センター陸部列、一対のセカンド陸部列、及び一対のショルダー陸部列）がタイヤ幅方向に区画されている。また、いずれかの陸部列（センター陸部列、一対のセカンド陸部列）には、タイヤ幅方向へ延びた複数本のラグ溝がタイヤ周方向に間隔を置いて設けられている。そして、複数本の主溝及び複数本のラグ溝によって、いずれかの前記陸部列が複数のブロックにタイヤ周方向に区画されている。   That is, the tread portion in the pneumatic tire according to the prior art is provided with a plurality of main grooves extending in the tire circumferential direction, and a plurality of main grooves and tread ends are provided in the tire circumferential direction. A land portion row (a center land portion row, a pair of second land portion rows, and a pair of shoulder land portion rows) is partitioned in the tire width direction. Further, in any land portion row (center land portion row, pair of second land portion rows), a plurality of lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction. One of the land portion rows is partitioned into a plurality of blocks in the tire circumferential direction by a plurality of main grooves and a plurality of lug grooves.

各ブロックには、タイヤ幅方向へ延びた２本の幅方向サイプがタイヤ周方向に分断するようにそれぞれ形成されている。また、幅方向サイプのサイプ底にクラックが発生することを抑えるため、各幅方向サイプは、サイプ底側に、円弧状断面の拡大部をそれぞれ有している。
特開平７−１７２１１１号公報 Each block is formed with two widthwise sipes extending in the tire width direction so as to be divided in the tire circumferential direction. Further, in order to suppress the occurrence of cracks at the sipe bottom of the width direction sipe, each width direction sipe has an enlarged portion of an arc-shaped cross section on the sipe bottom side.
JP-A-7-172111

ところで、先行技術に係る空気入りタイヤにおいては、氷雪上性能（氷雪上におけるトラクション性能等）を向上させるためには、ブロックに形成される幅方向サイプの本数を増加することにより、タイヤ幅方向のエッジ成分を増やして、エッジ効果を十分に高める必要がある。   By the way, in the pneumatic tire according to the prior art, in order to improve the performance on ice and snow (such as traction performance on ice and snow), by increasing the number of width-direction sipes formed in the block, It is necessary to increase the edge component sufficiently to increase the edge effect.

一方、ブロックに形成される幅方向サイプの本数を増加させると、ブロック自体の大きさが小さくなるために、ブロックの剛性が低下して、蹴り出し時におけるブロックの変形が大きくなり、ブロックのタイヤ周方向の側部に最も近い幅方向サイプのサイプ底にブロック欠けの要因になるクラックが発生し易くなって、ブロック耐久性が悪化するという問題がある。   On the other hand, if the number of sipe in the width direction formed on the block is increased, the size of the block itself is reduced, so that the rigidity of the block is reduced and the deformation of the block at the time of kicking is increased, and the block tire There is a problem that the crack durability is likely to occur at the sipe bottom of the width direction sipe closest to the side in the circumferential direction, and the block durability is deteriorated.

この問題は、サイプ底の拡大部の曲率半径を大きくすることによって、ある程度は抑制することが可能であるが、拡大部が大きくなることによって、またブロックの剛性が低下することになりかねない。   This problem can be suppressed to some extent by increasing the radius of curvature of the enlarged portion at the bottom of the sipe, but the rigidity of the block may be reduced by increasing the enlarged portion.

即ち、先行技術に係る空気入りタイヤにおいては、氷雪上性能の向上を図りつつ、ブロック耐久性を維持することは極めて困難であるという問題がある。   That is, in the pneumatic tire according to the prior art, there is a problem that it is extremely difficult to maintain the block durability while improving the performance on ice and snow.

そこで、本発明は、前述の問題を解決することができる、新規な構成の空気入りタイヤを提供することを目的とする。   Then, an object of this invention is to provide the pneumatic tire of a novel structure which can solve the above-mentioned problem.

本発明の第１の特徴（請求項１に記載の発明の特徴）は、トレッド部にタイヤ周方向へ延びた複数本の主溝が設けられ、複数本の前記主溝及びトレッド端によってタイヤ周方向へ延びた複数の陸部列がタイヤ幅方向に区画され、少なくともいずれかの前記陸部列にタイヤ幅方向へ延びた複数本のラグ溝がタイヤ周方向に間隔を置いて設けられ、複数本の前記主溝及び複数本の前記ラグ溝によっていずれかの前記陸部列が複数のブロックにタイヤ周方向に区画された空気入りタイヤにおいて、前記各ブロックにタイヤ幅方向へ延びた少なくとも３本以上の幅方向サイプが当該ブロックをタイヤ周方向に分断するようにそれぞれ形成され、各幅方向サイプはサイプ底側に円弧状断面の拡大部をそれぞれ有し、各ブロックにおける３本以上の前記幅方向サイプは、前記ブロックのタイヤ周方向の側部にそれぞれ最も近い２本の第１幅方向サイプと、２本の前記第１幅方向サイプとの間に介在した１本以上の第２幅方向サイプとからなり、前記第１幅方向サイプの前記拡大部は、前記ブロックのタイヤ周方向の側部側を指向してあって、その曲率半径は、前記第２幅方向サイプの前記拡大部の曲率半径よりも大きく設定されており、さらに、前記各ブロックのタイヤ周方向の一方側の側面及び他方側の側面には、前記第１幅方向サイプの前記拡大部があることによる該拡大部から前記一方側の側面及び他方側の側面までの距離の縮小を補う肉厚増加部が設けられ、その肉厚増加部の外周側の側面に、前記ブロックの内周側から外周側にいくほど前記第１幅方向サイプの外側の肉厚を小さくして外周端で前記肉厚増加部を設ける前の定常肉厚に一致させるテーパ面が形成されていることを要旨とする。   A first feature of the present invention (feature of the invention described in claim 1) is that a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and the tire circumference is defined by the plurality of main grooves and tread ends. A plurality of land portion rows extending in the tire direction are partitioned in the tire width direction, and at least one of the land portion rows is provided with a plurality of lug grooves extending in the tire width direction at intervals in the tire circumferential direction. In a pneumatic tire in which any of the land portion rows is partitioned into a plurality of blocks in the tire circumferential direction by the main grooves and the plurality of lug grooves, at least three of the blocks extend in the tire width direction. Each of the widthwise sipes is formed so as to divide the block in the tire circumferential direction. Each widthwise sipe has an enlarged portion having an arc-shaped cross section on the bottom side of the sipe. The directional sipe is at least one second width direction interposed between the two first width direction sipes closest to the tire circumferential side portion of the block and the two first width direction sipes. The enlarged portion of the first width direction sipe is directed to the side of the block in the tire circumferential direction, and the radius of curvature thereof is the same as that of the enlarged portion of the second width direction sipe. From the enlarged portion by the fact that the enlarged portion of the first width direction sipe is present on one side surface and the other side surface in the tire circumferential direction of each block. A thickness increasing portion is provided to compensate for the reduction in the distance to the side surface on the one side and the side surface on the other side, and the side surface on the outer peripheral side of the thickness increasing portion increases toward the outer peripheral side from the inner peripheral side of the block. Reduce the outer wall thickness of the first width sipe It is summarized as the tapered surface to match the steady thickness before the outer peripheral end provided with the thick increasing portion is formed.

第１の特徴によると、各ブロックにタイヤ幅方向へ延びた少なくとも３本以上の前記幅方向サイプがタイヤ周方向に当該ブロックを分断するようにそれぞれ形成されているため、タイヤ幅方向のエッジ成分を増やして、エッジ効果を十分に高めることができる。   According to the first feature, at least three or more of the widthwise sipes extending in the tire width direction are formed in each block so as to divide the block in the tire circumferential direction. To increase the edge effect sufficiently.

また、第１幅方向サイプのサイプ底の拡大部の曲率半径が第２幅方向サイプのサイプ底の拡大部の曲率半径よりも大きいため、各ブロックにおける幅方向サイプの本数の増加に伴い、蹴り出し時におけるブロックの変形が大きくなっても、ブロックのタイヤ周方向の側部に最も近い第１幅方向サイプのサイプ底に生じる応力集中を小さくすることができる。   Further, since the radius of curvature of the enlarged portion of the sipe bottom of the first width direction sipe is larger than the radius of curvature of the enlarged portion of the sipe bottom of the second width direction sipe, the kicking is increased as the number of width sipe in each block increases. Even if the deformation of the block at the time of unloading increases, the stress concentration generated at the sipe bottom of the first width direction sipe closest to the side portion in the tire circumferential direction of the block can be reduced.

また、第１幅方向サイプのサイプ底の拡大部の曲率半径を大きくすると、ブロックの剛性が低下するおそれがあるが、各ブロックのタイヤ周方向の一方側の側面及び他方側の側面に、サイプ底の拡大部があることによる拡大部から前記一方側の側面及び他方側の側面までの距離の縮小を補う肉厚増加部を設けているので、ブロックの周方向の長さを広げることができて、ブロックの剛性低下を抑制することができ、その結果、氷上性能の向上を図ることができる。つまり、氷上性能を落とさずに、サイプ底のクラックの発生を抑制することができる。   Further, if the radius of curvature of the enlarged portion of the sipe bottom of the first width direction sipe is increased, the rigidity of the block may be lowered. However, the sipe is formed on one side surface and the other side surface of each block in the tire circumferential direction. Since the thickness increasing part that compensates for the reduction in the distance from the enlarged part to the one side surface and the other side surface due to the presence of the enlarged part at the bottom is provided, the circumferential length of the block can be increased. Thus, it is possible to suppress a decrease in the rigidity of the block, and as a result, it is possible to improve the performance on ice. That is, the occurrence of cracks at the sipe bottom can be suppressed without degrading the performance on ice.

また、肉厚増加部の外周側の側面に、ブロックの内周側から外周側にいくほど第１幅方向サイプの外側の肉厚を小さくして外周端で肉厚増加部を設ける前の定常肉厚に一致させるテーパ面を形成しているので、トレッド表面付近のネガティブ比を低下させずに、氷雪上性能を維持することができる。この場合、テーパ面の角度を大きくすることにより、ブロック剛性をより高めることができる。   In addition, on the outer peripheral side of the thickness increasing portion, the outer thickness of the first width direction sipe is reduced as it goes from the inner peripheral side to the outer peripheral side of the block, and the steady state before the thickness increasing portion is provided at the outer peripheral end. Since the tapered surface matching the thickness is formed, the performance on ice and snow can be maintained without reducing the negative ratio near the tread surface. In this case, the block rigidity can be further increased by increasing the angle of the tapered surface.

本発明の第２の特徴（請求項２に記載の発明の特徴）は、第１の特徴に加えて、前記肉厚増加部を設ける前の前記第１幅方向サイプの外側の定常肉厚をａ、前記肉厚増加部が設けられた前記一方側の側面及び他方側の側面から前記第１幅方向サイプの前記拡大部のタイヤ周方向の外端までの距離をｂとした場合、
ａ＝ｂ
となっていることを要旨する。 According to a second feature of the present invention (a feature of the invention described in claim 2), in addition to the first feature, the steady thickness outside the first width direction sipe before providing the thickness increasing portion is increased. When the distance from the side surface on the one side and the side surface on the other side where the thickness increasing portion is provided to the outer end in the tire circumferential direction of the enlarged portion of the first width direction sipe is b,
a = b
It is a summary.

第２の特徴によると、前記第１幅方向サイプが開く方向のブロックの剪断剛性の低下抑制に特に有効である。   According to the second feature, it is particularly effective for suppressing a decrease in shear rigidity of the block in the direction in which the first width direction sipe opens.

本発明の第３の特徴（請求項３に記載の発明の特徴）は、第１の特徴に加えて、前記第１幅方向サイプの拡大部の断面積をＳ１、前記肉厚増加部の断面積をＳ２とした場合、
Ｓ１＝Ｓ２
となっていることを要旨とする。 According to a third feature of the present invention (a feature of the invention described in claim 3), in addition to the first feature, the cross-sectional area of the enlarged portion of the first width direction sipe is S1, and the thickness increase portion is cut off. When the area is S2,
S1 = S2
This is the summary.

第３の特徴によると、ブロックの圧縮剛性の低下抑制に特に有効である。   According to the 3rd characteristic, it is especially effective for suppression of the fall of the compression rigidity of a block.

本発明の第４の特徴（請求項４に記載の発明の特徴）は、第１の特徴から第３の特徴のうちのいずれかの特徴に加えて、前記ラグ溝として、少なくともいずれかの前記陸部列のタイヤ幅方向の一方側部分に、タイヤ幅方向へ延びた複数本の第１ラグ溝がタイヤ周方向に間隔を置いて設けられ、各第１ラグ溝の一端が前記主溝にそれぞれ開口されかつ各第１ラグ溝の他端がいずれかの前記陸部列にそれぞれ終端され、前記ラグ溝として、いずれかの前記陸部列のタイヤ幅方向の他方側部分に、タイヤ幅方向へ延びた複数本の第２ラグ溝がタイヤ周方向に間隔を置いて設けられ、各第２ラグ溝の一端がいずれかの前記陸部列にそれぞれ終端されかつ各第２ラグ溝の他端が前記主溝にそれぞれ開口され、いずれか前記陸部列に近接関係にある前記第１ラグ溝と前記第２ラグ溝を連通する複数本の連通サイプがタイヤ周方向に間隔を置いて形成され、複数本の前記主溝、複数本の前記第１ラグ溝、複数本の前記第２ラグ溝、及び複数本の前記連通サイプによっていずれかの前記陸部列が複数のブロックにタイヤ周方向に区画され、各ブロックのタイヤ幅方向の中央部分にタイヤ周方向へ延びかつ一対の小ブロックに分割する周方向サイプがそれぞれ形成され、前記各小ブロックにそれぞれ前記第１幅方向サイプと第２幅方向サイプが形成されていることを要旨とする。   According to a fourth feature of the present invention (a feature of the invention described in claim 4), in addition to any one of the first to third features, at least one of the lug grooves A plurality of first lug grooves extending in the tire width direction are provided at one side portion in the tire width direction of the land portion row at intervals in the tire circumferential direction, and one end of each first lug groove is formed in the main groove. Opened and the other end of each first lug groove is respectively terminated in any of the land portion rows, and the lug groove has a tire width direction on the other side portion in the tire width direction of any of the land portion rows. A plurality of second lug grooves extending in the tire circumferential direction are provided at intervals in the tire circumferential direction, and one end of each second lug groove is terminated in one of the land portion rows and the other end of each second lug groove Are respectively opened in the main grooves and are in proximity to any of the land rows. A plurality of communication sipes that communicate between the lug groove and the second lug groove are formed at intervals in the tire circumferential direction, the plurality of main grooves, the plurality of first lug grooves, and the plurality of second One of the land portion rows is partitioned into a plurality of blocks in the tire circumferential direction by a lug groove and a plurality of the communicating sipes, and extends in the tire circumferential direction at a central portion in the tire width direction of each block, and a pair of small blocks The gist is that circumferential sipe to be divided into two is formed, and the first width direction sipe and the second width direction sipe are respectively formed in each of the small blocks.

請求項１から請求項４のうちのいずれかの請求項に記載の発明によれば、タイヤ幅方向のエッジ成分を増やして、エッジ効果を十分に高めると共に、蹴り出し時におけるブロックの変形が大きくなっても、ブロックのタイヤ周方向の側部に最も近い第１幅方向サイプのサイプ底に生じる応力集中を小さくすることができる。従って、氷雪上性能の向上を図りつつ、ブロックのタイヤ周方向の側部に最も近い第１幅方向サイプのサイプ底にクラックが発生することを抑制して、ブロック耐久性を維持することができる。また、第１幅方向サイプのサイプ底のクラック防止のためにサイプ底の拡大部の曲率半径を大きくした場合にも、ブロックの剛性低下を抑制することができ、氷上性能を落とさずに、サイプ底のクラックの発生を抑制することができる。   According to the invention according to any one of claims 1 to 4, the edge component in the tire width direction is increased to sufficiently enhance the edge effect, and the deformation of the block at the time of kicking is large. Even if it becomes, the stress concentration which arises in the sipe bottom of the 1st width direction sipe nearest to the tire circumferential direction side part of a block can be made small. Therefore, it is possible to maintain the block durability by suppressing the occurrence of cracks in the sipe bottom of the first width direction sipe closest to the side in the tire circumferential direction of the block while improving the performance on ice and snow. . In addition, when the radius of curvature of the enlarged part of the sipe bottom is increased to prevent cracks at the sipe bottom in the first width direction sipe, the rigidity of the block can be suppressed and the sipe can be suppressed without degrading the performance on ice. The occurrence of cracks at the bottom can be suppressed.

本発明の実施形態について図１、図２（ａ）（ｂ）、及び図３を参照して説明する。ここで、図１は、本発明の実施形態に係る空気入りタイヤにおけるトレッド部の一部分の平面展開図、図２（ａ）は、本発明の実施形態に係るブロックの拡大図、図２（ｂ）は、図２（ａ）におけるIIB-IIB線に沿った断面図、図３は図２（ｂ）のIII部の誇張した断面図である。   An embodiment of the present invention will be described with reference to FIGS. 1, 2A and 2B, and FIG. Here, FIG. 1 is a plan development view of a part of a tread portion in a pneumatic tire according to an embodiment of the present invention, FIG. 2A is an enlarged view of a block according to the embodiment of the present invention, and FIG. ) Is a cross-sectional view taken along line IIB-IIB in FIG. 2A, and FIG. 3 is an exaggerated cross-sectional view of a portion III in FIG.

図１に示すように、本発明の実施形態に係る空気入りタイヤ１におけるトレッド３には、タイヤ周方向Ｃへ延びた複数本の主溝５が設けられており、複数本の主溝５及びトレッド端Ｅによって、タイヤ周方向Ｃへ延びた複数の陸部列７，９，１１がタイヤ幅方向Ｗに区画されている。なお、複数の陸部列７，９，１１は、センター陸部列７と、このセンター陸部列７のタイヤ幅方向Ｗ外側に配置した一対のセカンド陸部列９と、一対のセカンド陸部列９のタイヤ幅方向Ｗ外側に配置した一対のショルダー陸部列１１とからなる。   As shown in FIG. 1, the tread 3 in the pneumatic tire 1 according to the embodiment of the present invention is provided with a plurality of main grooves 5 extending in the tire circumferential direction C, and the plurality of main grooves 5 and A plurality of land portion rows 7, 9, and 11 extending in the tire circumferential direction C are partitioned in the tire width direction W by the tread end E. The plurality of land portion rows 7, 9, and 11 include a center land portion row 7, a pair of second land portion rows 9 arranged outside the center land portion row 7 in the tire width direction W, and a pair of second land portions. It consists of a pair of shoulder land part row | line | column 11 arrange | positioned on the tire width direction W outer side of row | line | column 9.

センター陸部列７及び一対のセカンド陸部列９（以下、適宜の陸部列７（９）という）のタイヤ幅方向Ｗの一方側部分には、タイヤ幅方向Ｗへ延びた複数本の第１ラグ溝１３がタイヤ周方向Ｃへ間隔を置いて設けられており、各第１ラグ溝１３の一端は、主溝５にそれぞれ開口されてあって、各第１ラグ溝１３の他端は、適宜の陸部列７（９）にそれぞれ終端されている。また、適宜の陸部列７（９）のタイヤ幅方向Ｗの他方側部分には、タイヤ幅方向Ｗへ延びた複数本の第２ラグ溝１５がタイヤ周方向Ｃへ間隔を置いて設けられており、各第２ラグ溝１５の一端は、適宜の陸部列７（９）にそれぞれ終端されてあって、各第２ラグ溝１５の他端は、主溝５にそれぞれ開口されている。更に、適宜の陸部列７（９）には、近接関係にある第１ラグ溝１３と第２ラグ溝１５を連通する複数本の連通サイプ１７がタイヤ周方向Ｃに間隔を置いて形成されている。   On one side portion in the tire width direction W of the center land portion row 7 and the pair of second land portion rows 9 (hereinafter, referred to as appropriate land portion rows 7 (9)), a plurality of first portions extending in the tire width direction W are provided. 1 lug grooves 13 are provided at intervals in the tire circumferential direction C, one end of each first lug groove 13 is opened in the main groove 5, and the other end of each first lug groove 13 is Each is terminated at an appropriate land portion row 7 (9). Further, a plurality of second lug grooves 15 extending in the tire width direction W are provided at intervals in the tire circumferential direction C on the other side portion of the appropriate land portion row 7 (9) in the tire width direction W. One end of each second lug groove 15 is terminated to an appropriate land portion row 7 (9), and the other end of each second lug groove 15 is opened to the main groove 5 respectively. . Further, in the appropriate land portion row 7 (9), a plurality of communicating sipes 17 that communicate the first lug groove 13 and the second lug groove 15 that are in a close relationship are formed at intervals in the tire circumferential direction C. ing.

そして、図１及び図２（ａ）に示すように、複数本の主溝５、複数本の第１ラグ溝１３、複数本の第２ラグ溝１５、及び複数本の連通サイプ１７によって、適宜の陸部列７（９）が複数のブロック１９にタイヤ周方向Ｃに区画されている。また、各ブロック１９のタイヤ幅方向Ｗの中央部分には、タイヤ周方向Ｃへ延びかつ一対の小ブロック２１に分割する周方向サイプ２３が形成されている。   As shown in FIG. 1 and FIG. 2A, the plurality of main grooves 5, the plurality of first lug grooves 13, the plurality of second lug grooves 15, and the plurality of communication sipes 17 are used as appropriate. The land portion row 7 (9) is partitioned into a plurality of blocks 19 in the tire circumferential direction C. Further, a circumferential sipe 23 that extends in the tire circumferential direction C and is divided into a pair of small blocks 21 is formed in the central portion of each block 19 in the tire width direction W.

また、ショルダー陸部列１１のタイヤ幅方向Ｗの中心側の部分にも、タイヤ幅方向Ｗへ延びた複数本のラグ溝１３、１５がタイヤ周方向Ｃへ間隔を置いて設けられており、各ラグ溝１３、１５によって、ショルダー陸部列１１が複数の小ブロック２１にタイヤ周方向Ｃに区画されている。   In addition, a plurality of lug grooves 13 and 15 extending in the tire width direction W are also provided at intervals in the tire circumferential direction C in the central portion of the shoulder land portion row 11 in the tire width direction W. The shoulder land portion row 11 is partitioned into a plurality of small blocks 21 in the tire circumferential direction C by the lug grooves 13 and 15.

ここで、センター陸部列７及び一対のセカンド陸部列９の小ブロック２１の幅と、ショルダー陸部列１１の小ブロック２１の幅の比は１００％〜１２０％の間に設定されている。   Here, the ratio of the width of the small block 21 of the center land portion row 7 and the pair of second land portion rows 9 to the width of the small block 21 of the shoulder land portion row 11 is set between 100% and 120%. .

次に、本発明の実施形態の要部について説明する。   Next, the main part of the embodiment of the present invention will be described.

図２（ａ）（ｂ）に示すように、各小ブロック２１のタイヤ周方向Ｃの一方側部分及び他方側部分には、タイヤ幅方向Ｗへ延びた２本の幅方向サイプ２５が、小ブロック２１をタイヤ周方向Ｃへ分断するようにそれぞれ形成されており、各幅方向サイプ２５は、サイプ底側に、円弧状断面の拡大部２７をそれぞれ有している。なお、幅方向サイプ２５の深さは主溝５よりも浅い。ここで、各小ブロック２１における４本の幅方向サイプ２５は、小ブロック２１のタイヤ周方向Ｃの側部にそれぞれ最も近い２本の第１幅方向サイプ２５Ａと、２本の第１幅方向サイプ２５Ａとの間に介在した２本の第２幅方向サイプ２５Ｂとからなっている。   As shown in FIGS. 2A and 2B, two width direction sipes 25 extending in the tire width direction W are small on one side portion and the other side portion in the tire circumferential direction C of each small block 21. Each block 21 is formed so as to be divided in the tire circumferential direction C, and each width-direction sipe 25 has an enlarged portion 27 having an arc-shaped cross section on the sipe bottom side. The depth of the width direction sipe 25 is shallower than that of the main groove 5. Here, the four width direction sipes 25 in each small block 21 are the two first width direction sipes 25A closest to the side of the small block 21 in the tire circumferential direction C, and the two first width directions. It consists of two second width direction sipes 25B interposed between the sipes 25A.

そして、第１幅方向サイプ２５Ａの拡大部２７の曲率半径は、第２幅方向サイプ２５Ｂの拡大部２７の曲率半径よりも大きくなっている。これにより、蹴り出し時におけるブロック１９の変形が大きくなっても、小ブロック２１のタイヤ周方向Ｃの側部に最も近い第１幅方向サイプ２５Ａのサイプ底に生じる応力集中を小さくすることができる。   The radius of curvature of the enlarged portion 27 of the first width direction sipe 25A is larger than the radius of curvature of the enlarged portion 27 of the second width direction sipe 25B. Thereby, even if the deformation of the block 19 during kicking increases, the stress concentration generated at the sipe bottom of the first width direction sipe 25A closest to the side portion in the tire circumferential direction C of the small block 21 can be reduced. .

また、第１幅方向サイプ２５Ａの拡大部２７の曲率半径に対する第２幅方向サイプ２５Ｂの拡大部２７の曲率半径の比（以下、拡大部２７の曲率半径比という）は、０．７〜０．９に設定されており、拡大部２７の曲率半径Ｒは１．６〜２．０くらいの大きさに設定されている。ここで、拡大部２７の曲率半径比を０．７以上に設定したのは、０．７未満に設定されると、第１幅方向サイプ２５Ａの拡大部２７の曲率半径が大きすぎて、小ブロック２１の剛性が大きく低下するからである。一方、拡大部２７の曲率半径比を０．９以下に設定したのは、０．９を超えて設定されると、第１幅方向サイプ２５Ａの拡大部２７の曲率半径が小さすぎて、小ブロック２１のタイヤ周方向Ｃの側部に最も近い第１幅方向サイプ２５Ａのサイプ底に生じる応力集中を十分に小さくすることができないからである。   The ratio of the radius of curvature of the enlarged portion 27 of the second width direction sipe 25B to the radius of curvature of the enlarged portion 27 of the first width direction sipe 25A (hereinafter referred to as the curvature radius ratio of the enlarged portion 27) is 0.7-0. .9, and the radius of curvature R of the enlarged portion 27 is set to about 1.6 to 2.0. Here, the reason why the curvature radius ratio of the enlarged portion 27 is set to 0.7 or more is that when it is set to less than 0.7, the radius of curvature of the enlarged portion 27 of the first width direction sipe 25A is too large and small. This is because the rigidity of the block 21 is greatly reduced. On the other hand, the reason why the radius of curvature of the enlarged portion 27 is set to 0.9 or less is that when it exceeds 0.9, the radius of curvature of the enlarged portion 27 of the first width direction sipe 25A is too small. This is because the stress concentration generated at the sipe bottom of the first width direction sipe 25A closest to the side of the block 21 in the tire circumferential direction C cannot be sufficiently reduced.

また、第１幅方向サイプ２５Ａの拡大部２７は、小ブロック２１のタイヤ周方向Ｃの側部側（タイヤ周方向Ｃの中心側の反対側）を指向してあって、第２幅方向サイプ２５Ｂの拡大部２７は、小ブロック２１のタイヤ周方向Ｃの中心側を指向している。これは、第１幅方向サイプ２５Ａの拡大部２７と第２幅方向サイプ２５Ｂの拡大部２７との距離が短くなりすぎて、第１幅方向サイプ２５Ａ又は第２幅方向サイプ２５Ｂのサイプ底にクラックが発生し易くなることを防ぐためである。   Further, the enlarged portion 27 of the first width direction sipe 25A is directed to the side portion side of the small block 21 in the tire circumferential direction C (the side opposite to the center side of the tire circumferential direction C), and the second width direction sipe. The enlarged portion 27 of 25B is directed to the center side of the small block 21 in the tire circumferential direction C. This is because the distance between the enlarged portion 27 of the first width direction sipe 25A and the enlarged portion 27 of the second width direction sipe 25B becomes too short, and the sipe bottom of the first width direction sipe 25A or the second width direction sipe 25B This is to prevent cracks from being easily generated.

更に、図３に示すように、各小ブロック２１のタイヤ周方向の一方側の側面２１ｂ及び他方側の側面２１ｂには、第１幅方向サイプ２５Ａの拡大部２７があることによる拡大部２７から一方側の側面２１ｂ及び他方側の側面２１ｂまでの距離ｃの縮小を補う肉厚増加部２１ａが設けられ、その肉厚増加部２１ａの外周側の側面には、小ブロック２１の内周側から外周側にいくほど第１幅方向サイプ２５Ａの外側の肉厚を小さくして外周端で肉厚増加部２１ａを設ける前の定常肉厚ａに一致させるテーパ面２１ｃが形成されている。   Further, as shown in FIG. 3, from the enlarged portion 27 due to the presence of the enlarged portion 27 of the first width direction sipe 25 </ b> A on one side surface 21 b and the other side surface 21 b in the tire circumferential direction of each small block 21. A thickness increasing portion 21a that compensates for the reduction of the distance c to the one side surface 21b and the other side surface 21b is provided, and the outer peripheral side surface of the thickness increasing portion 21a is provided from the inner peripheral side of the small block 21. A taper surface 21c is formed so that the thickness on the outer side of the first width direction sipe 25A is reduced toward the outer peripheral side so as to coincide with the steady thickness a before the thickness increasing portion 21a is provided at the outer peripheral end.

このテーパ面２１ｃのタイヤ半径方向の高さ２１ｃｈは、隣接するラグ溝１３、１５の深さに対して２０〜８０％に設定されている。また、テーパ面２１ｃのテーパ角度θ（路面に垂直な方向に対する角度）は、５°〜１０°に設定されている。ここで、テーパ角度θが５°より小さいと、小ブロック２１の剛性が低下してブロック欠けを起こす懸念が増し、テーパ角度θが１０°より大きいと、小ブロック２１の剛性は確保されるものの、隣接するラグ溝１３、１５の幅が小さくなり、スタッドレスタイヤの本来の性能の一つである排雪性が低下する。   The height 21ch of the tapered surface 21c in the tire radial direction is set to 20 to 80% with respect to the depth of the adjacent lug grooves 13 and 15. The taper angle 21c of the taper surface 21c (angle with respect to the direction perpendicular to the road surface) is set to 5 ° to 10 °. Here, if the taper angle θ is smaller than 5 °, the rigidity of the small block 21 is lowered and there is a concern that the block is chipped. If the taper angle θ is larger than 10 °, the rigidity of the small block 21 is ensured. The width of the adjacent lug grooves 13 and 15 is reduced, and the snow drainage, which is one of the original performances of the studless tire, is reduced.

この場合、具体的な実施例１においては、肉厚増加部２１ａを設ける前の第１幅方向サイプ２５Ａの外側の定常肉厚をａ、肉厚増加部２１ａが設けられた一方側の側面２１ｂ及び他方側の側面２１ｂから第１幅方向サイプ２５Ａの前記拡大部２７のタイヤ周方向の外端までの距離をｂとした場合、
ａ＝ｂ
の条件を満たすように、肉厚増加部２１ａを設けて小ブロック２１のタイヤ周方向の長さを拡げている。 In this case, in the specific embodiment 1, the steady thickness outside the first width direction sipe 25A before providing the thickness increasing portion 21a is a, and the side surface 21b on one side where the thickness increasing portion 21a is provided. When the distance from the side surface 21b on the other side to the outer end in the tire circumferential direction of the enlarged portion 27 of the first width direction sipe 25A is b,
a = b
In order to satisfy the above condition, the thickness increasing portion 21a is provided to increase the length of the small block 21 in the tire circumferential direction.

また、具体的な実施例２としては、第１幅方向サイプ２５Ａの拡大部２７の断面の面積をＳ１、肉厚増加部２１ａの断面の面積をＳ２とした場合、
Ｓ１＝Ｓ２
の条件を満たすように、肉厚増加部２１ａを設けて小ブロック２１のタイヤ周方向の長さを拡げている。 As a specific example 2, when the area of the cross section of the enlarged portion 27 of the first width direction sipe 25A is S1, and the area of the cross section of the thickness increasing portion 21a is S2,
S1 = S2
In order to satisfy the above condition, the thickness increasing portion 21a is provided to increase the length of the small block 21 in the tire circumferential direction.

なお、各小ブロック２１の主溝５側の縁部分には、タイヤ幅方向Ｗへ延びた短サイプ２９が形成されている。   A short sipe 29 extending in the tire width direction W is formed at an edge portion of each small block 21 on the main groove 5 side.

続いて、本発明の実施形態の作用及び効果について説明する。   Then, the effect | action and effect of embodiment of this invention are demonstrated.

各小ブロック２１にタイヤ幅方向Ｗへ延びた４本の幅方向サイプ２５がタイヤ周方向Ｃに分断するようにそれぞれ形成されているため、タイヤ幅方向Ｗのエッジ成分を増やして、エッジ効果を十分に高めることができる。   Since the four width direction sipes 25 extending in the tire width direction W are formed in each small block 21 so as to be divided in the tire circumferential direction C, the edge component in the tire width direction W is increased, and the edge effect is increased. It can be raised enough.

また、第１幅方向サイプ２５Ａの拡大部２７の曲率半径が第２幅方向サイプ２５Ｂの拡大部２７の曲率半径よりも大きいため、各小ブロック２１における幅方向サイプ２５の本数の増加に伴い、蹴り出し時におけるブロック１９の変形が大きくなっても、前述のように、小ブロック２１のタイヤ周方向Ｃの側部に最も近い第１幅方向サイプ２５Ａのサイプ底に生じる応力集中を小さくすることができる。   Further, since the radius of curvature of the enlarged portion 27 of the first width direction sipe 25A is larger than the radius of curvature of the enlarged portion 27 of the second width direction sipe 25B, as the number of the width direction sipes 25 in each small block 21 increases, Even if the deformation of the block 19 at the time of kicking increases, the stress concentration generated at the sipe bottom of the first width direction sipe 25A closest to the side portion in the tire circumferential direction C of the small block 21 is reduced as described above. Can do.

また、第１幅方向サイプ２５Ａのサイプ底の拡大部２７の曲率半径を大きくすると、小ブロック２１の剛性が低下するおそれがあるが、各小ブロック２１のタイヤ周方向の一方側の側面２１ｂ及び他方側の側面２１ｂに、サイプ底の拡大部２７があることによる拡大部２７から前記一方側の側面２１ｂ及び他方側の側面２１ｂまでの距離ｃの縮小を補う肉厚増加部２１ａを設けているので、小ブロック２１の周方向の長さを広げることができて、小ブロック２１の剛性低下を抑制することができる。従って、氷上性能を落とさずに、サイプ底のクラックの発生を抑制することができる。   In addition, when the radius of curvature of the enlarged portion 27 at the sipe bottom of the first width direction sipe 25A is increased, the rigidity of the small block 21 may be reduced, but the side surface 21b on one side in the tire circumferential direction of each small block 21 and On the other side surface 21b, there is provided a thickness increasing portion 21a that compensates for the reduction in the distance c from the enlarged portion 27 to the one side surface 21b and the other side surface 21b due to the presence of the enlarged portion 27 at the sipe bottom. Therefore, the length of the small block 21 in the circumferential direction can be widened, and a decrease in rigidity of the small block 21 can be suppressed. Therefore, the occurrence of cracks at the sipe bottom can be suppressed without degrading the performance on ice.

また、肉厚増加部２１ａの外周側の側面に、小ブロック２１の内周側から外周側にいくほど第１幅方向サイプ２５Ａの外側の肉厚を小さくして外周端で肉厚増加部２１ａを設ける前の定常肉厚ａに一致させるテーパ面２１ｃを形成しているので、トレッド表面付近のネガティブ比を低下させずに、氷雪上性能を維持することができる。   Further, on the outer peripheral side of the thickness increasing portion 21a, the thickness on the outer side of the first width direction sipe 25A is reduced toward the outer peripheral side from the inner peripheral side of the small block 21 to increase the thickness increasing portion 21a at the outer peripheral end. Since the tapered surface 21c is formed so as to match the steady wall thickness a before the provision of, the performance on ice and snow can be maintained without lowering the negative ratio near the tread surface.

以上の如き、本発明の実施形態に係る空気入りタイヤ１によれば、氷雪上性能の向上を図りつつ、小ブロック２１のタイヤ周方向Ｃの側部に最も近い第１幅方向サイプ２５Ａのサイプ底にクラックが発生することを抑制して、ブロック耐久性を維持することができる。   As described above, according to the pneumatic tire 1 according to the embodiment of the present invention, the sipe of the first width direction sipe 25A closest to the side portion in the tire circumferential direction C of the small block 21 while improving the performance on ice and snow. Block durability can be maintained by suppressing the occurrence of cracks at the bottom.

なお、本発明は、前述の実施形態の説明に限られるものではなく、例えば、ブロック１９を一対の小ブロック２１に分割する周方向サイプ２３を省略し、各ブロック１９にタイヤ幅方向Ｗへ延びた３本以上の幅方向サイプ２５をタイヤ周方向Ｃへ分断するようにそれぞれ形成する等、その他、種々の態様で実施可能である。   The present invention is not limited to the description of the above-described embodiment. For example, the circumferential sipes 23 that divide the block 19 into a pair of small blocks 21 are omitted, and the blocks 19 extend in the tire width direction W. In addition, three or more width-direction sipes 25 are formed so as to be divided in the tire circumferential direction C, and various other modes can be implemented.

また、本発明に包含される権利範囲は、これらの実施形態に限定されないものである。   Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

次に本発明の実施例と比較例について試験した結果について説明する。   Next, the results of testing the examples and comparative examples of the present invention will be described.

（試験サンプル）
（１）実施例１は、前述したように、ａ＝ｂの条件を満たしながら、肉厚増加部を形成し、小ブロックの底部の周方向長さを拡げた本発明品である。 (Test sample)
(1) As described above, Example 1 is a product of the present invention in which the thickness increasing portion is formed and the circumferential length of the bottom portion of the small block is expanded while satisfying the condition of a = b.

（２）実施例２は、前述したように、Ｓ１＝Ｓ２の条件を満たしながら、肉厚増加部を形成し、小ブロックの底部の周方向長さを拡げた本発明品である。   (2) As described above, Example 2 is a product of the present invention in which the thickness increasing portion is formed and the circumferential length of the bottom portion of the small block is expanded while satisfying the condition of S1 = S2.

（３）比較例は、肉厚増加部を設けず、小ブロックの底部の周方向長さを拡げてないものである。   (3) In the comparative example, the thickness increasing portion is not provided, and the circumferential length of the bottom portion of the small block is not expanded.

（試験の具体的内容）
タイヤサイズは共通の「１１Ｒ２２．５ １６ＰＲ ＳＷ０１Ｚ」であり、これらをリムに組み付けて、所定圧の空気を充填する。そして、それぞれのタイヤを車両に装着した状態で氷上トラクション試験を行った。氷上トラクション試験は、氷上路面上で車両を発進させて、５ｋｍ／ｈのアイドリング状態から３速にてエンジン回転数１５００ｒｐｍまで上昇させ、５０ｍ進んだときのタイムで測定した。その結果を表１に示す。

Figure 0005060973
(Details of the test)
The tire size is a common “11R22.5 16PR SW01Z”, and these are assembled to the rim and filled with air of a predetermined pressure. And the traction test on ice was done in the state which mounted | worn each tire to the vehicle. In the traction test on ice, the vehicle was started on the road surface on ice, measured from the idling state of 5 km / h to the engine speed of 1500 rpm at the third speed, and the time when the vehicle advanced 50 m was measured. The results are shown in Table 1.
Figure 0005060973

この表から分かるように、発明品（実施例１、２）は、比較例に比べて、氷上トラクション性能の向上を図ることができた。   As can be seen from this table, the inventive products (Examples 1 and 2) were able to improve the traction performance on ice compared to the comparative examples.

本発明の実施形態に係る空気入りタイヤにおけるトレッド部の一部分の平面展開図である。It is a plane development view of a part of a tread part in a pneumatic tire concerning an embodiment of the present invention. 図２（ａ）は、本発明の実施形態に係るブロックの拡大図、図２（ｂ）は、図２（ａ）におけるIIB-IIB線に沿った図である。FIG. 2A is an enlarged view of a block according to the embodiment of the present invention, and FIG. 2B is a view taken along line IIB-IIB in FIG. 図２（ｂ）のIII部の誇張した断面図である。FIG. 3 is an exaggerated cross-sectional view of a portion III in FIG.

符号の説明Explanation of symbols

１ 空気入りタイヤ
３ トレッド
５ 主溝
７ センター陸部列
９ セカンド陸部列
１１ ショルダー陸部列
１３ 第１ラグ溝
１５ 第２ラグ溝
１７ 連通サイプ
１９ ブロック
２１ 小ブロック
２１ａ 肉厚増加部
２１ｂ 一方側及び他方側の側面
２１ｃ テーパ面
２３ 周方向サイプ
２５ 幅方向サイプ
２５Ａ 第１幅方向サイプ
２５Ｂ 第２幅方向サイプ
２７ 拡大部 DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Tread 5 Main groove 7 Center land part row | line 9 Second land part row | line | column 11 Shoulder land portion row | line | column 13 1st lug groove 15 2nd lug groove 17 Communication sipes 19 Block 21 Small block 21a Thickness increase part 21b One side And the other side surface 21c taper surface 23 circumferential sipe 25 width direction sipe 25A first width direction sipe 25B second width direction sipe 27 enlarged portion

Claims (4)

トレッド部にタイヤ周方向へ延びた複数本の主溝が設けられ、複数本の前記主溝及びトレッド端によってタイヤ周方向へ延びた複数の陸部列がタイヤ幅方向に区画され、少なくともいずれかの前記陸部列にタイヤ幅方向へ延びた複数本のラグ溝がタイヤ周方向に間隔を置いて設けられ、複数本の前記主溝及び複数本の前記ラグ溝によっていずれかの前記陸部列が複数のブロックにタイヤ周方向に区画された空気入りタイヤにおいて、
前記各ブロックにタイヤ幅方向へ延びた少なくとも３本以上の幅方向サイプが当該ブロックをタイヤ周方向に分断するようにそれぞれ形成され、
各幅方向サイプはサイプ底側に円弧状断面の拡大部をそれぞれ有し、各ブロックにおける３本以上の前記幅方向サイプは、前記ブロックのタイヤ周方向の側部にそれぞれ最も近い２本の第１幅方向サイプと、２本の前記第１幅方向サイプとの間に介在した１本以上の第２幅方向サイプとからなり、
前記第１幅方向サイプの前記拡大部は、前記ブロックのタイヤ周方向の側部側を指向してあって、その曲率半径は、前記第２幅方向サイプの前記拡大部の曲率半径よりも大きく設定されており、
さらに、前記各ブロックのタイヤ周方向の一方側の側面及び他方側の側面には、前記第１幅方向サイプの前記拡大部があることによる該拡大部から前記一方側の側面及び他方側の側面までの距離の縮小を補う肉厚増加部が設けられ、その肉厚増加部の外周側の側面に、前記ブロックの内周側から外周側にいくほど前記第１幅方向サイプの外側の肉厚を小さくして外周端で前記肉厚増加部を設ける前の定常肉厚に一致させるテーパ面が形成されていることを特徴とする空気入りタイヤ。 A plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and a plurality of land portion rows extending in the tire circumferential direction by the plurality of main grooves and tread ends are partitioned in the tire width direction, and at least one of them A plurality of lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction in the land portion row, and any one of the land portion rows is formed by the plurality of main grooves and the plurality of lug grooves. In a pneumatic tire divided into a plurality of blocks in the tire circumferential direction,
At least three or more widthwise sipes extending in the tire width direction are formed in each block so as to divide the block in the tire circumferential direction, respectively.
Each width-direction sipe has an enlarged portion having an arc-shaped cross section on the bottom side of the sipe, and three or more width-direction sipes in each block are two closest to the side portions in the tire circumferential direction of the block. And one or more second width direction sipes interposed between the first width direction sipes and the two first width direction sipes,
The enlarged portion of the first width direction sipe is directed to the side of the block in the tire circumferential direction, and its radius of curvature is larger than the radius of curvature of the enlarged portion of the second width direction sipe. Is set,
Further, the side surface on the one side and the side surface on the other side from the enlarged portion due to the presence of the enlarged portion of the first width direction sipe on the one side surface and the other side surface in the tire circumferential direction of each block. A thickness increasing portion is provided to compensate for the reduction in the distance to the outer peripheral side of the thickness increasing portion, and the thickness on the outer side of the first width direction sipe increases from the inner peripheral side to the outer peripheral side of the block. A pneumatic tire is characterized in that a tapered surface is formed so as to match the steady thickness before the thickness increasing portion is provided at the outer peripheral end. 前記肉厚増加部を設ける前の前記第１幅方向サイプの外側の定常肉厚をａ、前記肉厚増加部が設けられた前記一方側の側面及び他方側の側面から前記第１幅方向サイプの前記拡大部のタイヤ周方向の外端までの距離をｂとした場合、
ａ＝ｂ
となっていることを特徴とする請求項１に記載の空気入りタイヤ。 The steady-state thickness outside the first widthwise sipe before providing the thickness increasing portion is a, the first widthwise sipe from the one side surface and the other side surface where the thickness increasing portion is provided When the distance to the outer end in the tire circumferential direction of the enlarged portion is b,
a = b
The pneumatic tire according to claim 1, wherein: 前記第１幅方向サイプの前記拡大部の断面積をＳ１、前記肉厚増加部の断面積をＳ２とした場合、
Ｓ１＝Ｓ２
となっていることを特徴とする請求項１に記載の空気入りタイヤ。 When the sectional area of the enlarged portion of the first width direction sipe is S1, and the sectional area of the thickness increasing portion is S2,
S1 = S2
The pneumatic tire according to claim 1, wherein: 前記ラグ溝として、少なくともいずれかの前記陸部列のタイヤ幅方向の一方側部分に、タイヤ幅方向へ延びた複数本の第１ラグ溝がタイヤ周方向に間隔を置いて設けられ、各第１ラグ溝の一端が前記主溝にそれぞれ開口されかつ各第１ラグ溝の他端がいずれかの前記陸部列にそれぞれ終端され、
前記ラグ溝として、いずれかの前記陸部列のタイヤ幅方向の他方側部分に、タイヤ幅方向へ延びた複数本の第２ラグ溝がタイヤ周方向に間隔を置いて設けられ、各第２ラグ溝の一端がいずれかの前記陸部列にそれぞれ終端されかつ各第２ラグ溝の他端が前記主溝にそれぞれ開口され、
いずれか前記陸部列に近接関係にある前記第１ラグ溝と前記第２ラグ溝を連通する複数本の連通サイプがタイヤ周方向に間隔を置いて形成され、
複数本の前記主溝、複数本の前記第１ラグ溝、複数本の前記第２ラグ溝、及び複数本の前記連通サイプによっていずれかの前記陸部列が複数のブロックにタイヤ周方向に区画され、各ブロックのタイヤ幅方向の中央部分にタイヤ周方向へ延びかつ一対の小ブロックに分割する周方向サイプがそれぞれ形成され、
前記各小ブロックにそれぞれ前記第１幅方向サイプと第２幅方向サイプが形成されていることを特徴とする請求項１〜３のいずれか１項に記載の空気入りタイヤ。 As the lug grooves, a plurality of first lug grooves extending in the tire width direction are provided at intervals in the tire circumferential direction on at least one side portion of the land portion row in the tire width direction. One end of each lug groove is opened to the main groove, and the other end of each first lug groove is terminated to any of the land portion rows,
As the lug grooves, a plurality of second lug grooves extending in the tire width direction are provided on the other side portion in the tire width direction of any of the land portion rows at intervals in the tire circumferential direction. One end of each lug groove is terminated in one of the land portion rows, and the other end of each second lug groove is opened in the main groove, respectively.
A plurality of communicating sipes communicating with the first lug groove and the second lug groove in proximity to any of the land portion rows are formed at intervals in the tire circumferential direction;
The plurality of main grooves, the plurality of first lug grooves, the plurality of second lug grooves, and the plurality of communication sipes divide one of the land portion rows into a plurality of blocks in the tire circumferential direction. And a circumferential sipe that extends in the tire circumferential direction and divides into a pair of small blocks is formed in the center portion of the tire width direction of each block,
The pneumatic tire according to any one of claims 1 to 3, wherein the first width direction sipe and the second width direction sipe are formed in each of the small blocks.
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