Pneumatic tire

Abstract

To provide a pneumatic tire that can exert a traction effect in a plurality of directions.SOLUTION: A pneumatic tire comprises a pair of main grooves, lateral grooves and vertical grooves, where a center land has four center blocks repeatedly arranged in a tire circumferential direction. The four center blocks respectively comprise concave parts opening to the main grooves and the lateral grooves or the vertical grooves, and whose one ends are closed. When the concave parts provided in the four center blocks are defined as first-fourth concave parts, the first concave part and the second concave part extend along a direction inclining in one direction with respect to a tire equator line, and the third concave part and the fourth concave part extend along a direction inclining in the other direction with respect to the tire equator line. The first concave part opens in the opposite direction of the second concave part, and the third concave part opens in the opposite direction of the fourth concave part, where respective groove widths of the first-fourth concave parts are 5.0 mm or more.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires.

Background Art

[0002] In off-road pneumatic tires intended for driving on rough roads including muddy areas and rocky fields, generally, a tread pattern mainly composed of lateral grooves and blocks with many edge components is adopted. To improve the driving performance of such tires, it is desirable to obtain a traction effect in multiple directions due to the biting of mud, rocks, etc. on the road surface. Also, in enhancing the traction effect, it is essential to ensure the block rigidity.

[0003] Patent Document 1 describes an off-road pneumatic tire including a pair of main grooves extending along the tire circumferential direction, lateral grooves connecting the pair of main grooves, longitudinal grooves connecting adjacent lateral grooves in the tire circumferential direction, and a plurality of center blocks partitioned by the pair of main grooves, lateral grooves, and longitudinal grooves. The center blocks are provided with fine grooves opening into the main grooves and recesses opening into the lateral grooves, and their opening directions are different.

[0004] However, in Patent Document 1, since the fine grooves opening into the main grooves are so narrow that they are positioned equivalently to sipe in terms of the influence on block rigidity and groove area, it is considered that there is almost no traction effect due to the biting of mud, rocks, etc.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present disclosure is to provide a pneumatic tire capable of exerting a traction effect in a plurality of directions.

Means for Solving the Problems

[0007] The pneumatic tire of the present disclosure includes a pair of main grooves that extend along the tire circumferential direction on both sides of the tire equator line of the tread and partition the tread into three rows of lands, a plurality of transverse grooves that are spaced apart from each other in the tire circumferential direction and extend along the tire axial direction to connect the pair of main grooves, and a plurality of longitudinal grooves that extend along the tire circumferential direction between the pair of main grooves to connect the adjacent plurality of transverse grooves. Among the three rows of lands, the center land located between the pair of main grooves repeats four center blocks partitioned by the transverse grooves and the longitudinal grooves in the tire circumferential direction. Each of the four center blocks includes a recess that opens into the main groove, the transverse groove, or the longitudinal groove and has one end closed. When the recesses provided in the four center blocks are referred to as the first to fourth recesses, the first recess and the second recess extend along a direction inclined in one direction with respect to the tire equator line, the third recess and the fourth recess extend along a direction inclined in the other direction with respect to the tire equator line, the first recess opens in the direction opposite to the second recess, the third recess opens in the direction opposite to the fourth recess, and the groove width of each of the first to fourth recesses is 5.0 mm or more.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of a pneumatic tire will be described with reference to FIGS. 1 to 3. In each figure, the dimensional ratio in the drawing and the actual dimensional ratio do not necessarily match, and the dimensional ratios between the drawings do not necessarily match either.

[0010] In each figure, the first direction D1 is the tire axial direction D1 parallel to the tire rotation axis of the pneumatic tire (hereinafter, also simply referred to as "tire") 1, the second direction D2 is the tire diameter direction D2 which is the diameter direction of the tire 1, and the third direction D3 is the tire circumferential direction D3 around the tire rotation axis.

[0011] In the tire axial direction D1, the inner side is the side closer to the tire equatorial plane S1, and the outer side is the side farther from the tire equatorial plane S1. In the tire diameter direction D2, the inner side is the side closer to the tire rotation axis, and the outer side is the side farther from the tire rotation axis. Also, one direction in the tire axial direction D1 is referred to as the first axial direction D11, and the reverse direction of the first axial direction D11 is referred to as the second axial direction D12. One direction in the tire circumferential direction D3 is referred to as the first circumferential direction D31, and the reverse direction of the first circumferential direction D31 is referred to as the second circumferential direction D32.

[0012] The tire equatorial plane S1 is a plane orthogonal to the tire rotation axis and located at the center of the tire 1 in the tire axial direction D1, and the tire meridian plane is a plane including the tire rotation axis and orthogonal to the tire equatorial plane S1. Also, the tire equator line L1 is a line where the outer surface of the tire 1 in the tire diameter direction D2 intersects the tire equatorial plane S1.

[0013] As shown in FIG. 1, the tire 1 includes a pair of bead portions 11, 11, a pair of sidewalls 12, 12 extending outward in the tire diameter direction D2 from each bead portion 11, 11, a tread 13 connected to the outer ends in the tire diameter direction D2 of the pair of sidewalls 12, 12, a carcass ply 14 extending so as to span between the pair of bead portions 11, 11, and an inner liner 15 located on the innermost side of the tire 1. The tire 1 according to the present embodiment is an off-road tire intended for running on rough roads including muddy areas and rocky fields, but is not limited thereto.

[0014] As shown in FIGS. 2 and 3, the tire 1 includes a pair of main grooves 2, 2 that continuously extend along the tire circumferential direction D3 on both sides of the tire equator line L1 of the tread 13, a plurality of lateral grooves 3 that connect the pair of main grooves 2, and a plurality of longitudinal grooves 4 that connect the adjacent plurality of lateral grooves 3. From the viewpoint of exerting a traction effect, the main groove 2 preferably extends in a zigzag shape.

[0015] The plurality of lateral grooves 3 are arranged apart from each other in the tire circumferential direction D3. And the lateral groove 3 extends along the tire axial direction D1. From the viewpoint of exerting a traction effect in a plurality of directions, the lateral groove 3 is preferably inclined with respect to the tire axial direction D1. In the present embodiment, the groove depth of the lateral groove 3 is the same as the groove depth of the main groove 2.

[0016] The lateral groove 3 has a bending point 31. Thereby, the edge component of the center block 9 described later can be increased, and the traction performance of the tire 1 can be improved. The lateral grooves 3, 3 adjacent to each other in the tire circumferential direction D3 are referred to as a first lateral groove 3a and a second lateral groove 3b, respectively. And the bending points 31 provided in each of the lateral grooves 3a, 3b are referred to as a first bending point 31a and a second bending point 31b, respectively. In the present embodiment, the position of the first bending point 31a of the first lateral groove 3a is different from the position of the second bending point 31b of the second lateral groove 3b in the tire axial direction D1. Note that the lateral groove 3 is not limited to the above.

[0017] The longitudinal groove 4 extends along the tire circumferential direction D3 between the pair of main grooves 2. And the longitudinal groove 4 connects the first lateral groove 3a and the second lateral groove 3b adjacent to each other in the tire circumferential direction D3. From the viewpoint of exerting a traction effect in a plurality of directions, the longitudinal groove 4 is preferably inclined with respect to the tire circumferential direction D3. In the present embodiment, the longitudinal groove 4 extends discontinuously along the tire circumferential direction D3 and intersects the first lateral groove 3a and the second lateral groove 3b at substantially right angles (80 degrees to 100 degrees).

[0018] The longitudinal groove 4 extending from the second transverse groove 3b to one side in the tire circumferential direction D3 is referred to as the first longitudinal groove 4a, and the longitudinal groove 4 extending from the transverse groove 3 to the other side in the tire circumferential direction D3 is referred to as the second longitudinal groove 4b. The first longitudinal groove 4a and the second longitudinal groove 4b are arranged adjacent to each other in the tire circumferential direction D3. The shape of the first longitudinal groove 4a is different from the shape of the second longitudinal groove 4b. Specifically, the first longitudinal groove 4a is formed linearly, and the second longitudinal groove 4b is formed in a substantially Z shape. And the groove depth of the longitudinal groove 4 is the same as the groove depths of the main groove 2 and the transverse groove 3. Note that the longitudinal groove 4 is not limited to the above.

[0019] The tread 13 includes three rows of lands 5 partitioned by a pair of main grooves 2. These three rows of lands 5 include a center land 6 located between the pair of main grooves 2 and a pair of shoulder lands 7, 7 located outside the main grooves 2 in the tire axial direction D1. And the tire 1 includes shoulder transverse grooves 8 extending outward from the main grooves 2 in the tire axial direction D1. The shoulder land 7 is partitioned into a plurality of shoulder blocks 71 by the shoulder transverse grooves 8.

[0020] As shown in FIG. 3, the center land 6 includes a plurality of center blocks 9 partitioned by the transverse groove 3, the first longitudinal groove 4a, and the second longitudinal groove 4b. The center land 6 is formed by repeatedly arranging four mutually adjacent center blocks 9 (the first to fourth center blocks 9a to 9d described later) in the tire circumferential direction D3. The shape of the center block 9 is determined by the shapes of the main groove 2, the transverse groove 3, the first longitudinal groove 4a, and the second longitudinal groove 4b.

[0021] The center block 9 includes a recess 91 that opens into any one of the main groove 2, the transverse groove 3, the first longitudinal groove 4a, or the second longitudinal groove 4b and has one end closed. One recess 91 is arranged for one center block 9. In the present embodiment, the recess 91 is formed linearly. The wall surface 911 at one end of the recess 91 is inclined with respect to the opening direction and is parallel to a part of the transverse groove 3 adjacent to the recess 91 in the direction opposite to the opening direction (closing direction) of the recess 91. Note that the recess 91 is not limited to the above. The opening direction of the recess 91 is the direction from the wall surface 911 to the opening position of the recess 91 and along the central axis of the recess 91.

[0022] From the viewpoint of exerting the traction effect, the groove width W1 of the recess 91 is preferably 5.0 mm or more. The groove width W1 of the recess 91 refers to the groove width at the opening position of the recess 91. The groove width W1 of the recess 91 is preferably 50% to 70% of the groove width W2 (see FIG. 1) of the main groove 2. By setting the groove width W1 of the recess 91 to 50% or more of the groove width W2 of the main groove 2, the traction effect can be improved. By setting the groove width W1 of the recess 91 to 70% or less of the groove width W2 of the main groove 2, the rigidity of the center block 9 can be ensured. And from the viewpoint of ensuring the rigidity of the center block 9 and exerting the traction effect, the recess 91 preferably extends with a constant groove width W1 from the opening position.

[0023] From the viewpoint of exerting the traction effect, the groove length L1 of the recess 91 is preferably larger than the groove width W1 of the recess 91. And from the viewpoint of ensuring the rigidity of the center block 9 and exerting the traction effect, the groove length L1 of the recess 91 is preferably 30% to 70% of the length L2 from the opening position of the recess 91 to the end of the center block 9 that intersects on the extension line of the recess 91.

[0024] From the viewpoint of ensuring wear resistance, the groove depth of the recess 91 is preferably 40% or more of the groove depth of the main groove 2. In the present embodiment, the groove depth of the recess 91 is the same as the groove depths of the main groove 2, the lateral groove 3, and the longitudinal groove 4, but it is not limited thereto. For example, the groove depth of the recess 91 may be smaller than the groove depths of the main groove 2, the lateral groove 3, and the longitudinal groove 4. The groove width W1, the groove length L1, and the groove depth of the recess 91 are appropriately set according to the design of the tread pattern, the block rigidity, the traction performance, the drainage performance, and the like.

[0025] Here, the center block 9 adjacent to the first longitudinal groove 4a in the second axial direction D12 is defined as the first center block 9a, the center block 9 adjacent to the first longitudinal groove 4a in the first axial direction D11 is defined as the second center block 9b, the center block 9 adjacent to the second longitudinal groove 4b in the second axial direction D12 is defined as the third center block 9c, and the center block 9 adjacent to the second longitudinal groove 4b in the first axial direction D11 is defined as the fourth center block 9d. And the recesses 91 provided in the first to fourth center blocks 9a, 9b, 9c, 9d are defined as the first to fourth recesses 91a to 91d. And the transverse groove 3 that intersects with the first longitudinal groove 4a on the first circumferential direction D31 side (the transverse groove 3 that intersects with the second longitudinal groove 4b on the second circumferential direction D32 side) is defined as the first transverse groove 3a, and the transverse groove 3 that intersects with the first longitudinal groove 4a on the second circumferential direction D32 side (the transverse groove 3 that intersects with the second longitudinal groove 4b on the first circumferential direction D31 side) is defined as the second transverse groove 3b. Note that the first to fourth center blocks 9a, 9b, 9c, 9d are not limited to the above positions. For example, the center block 9 adjacent to the first longitudinal groove 4a in the first axial direction D11 may be defined as the first center block 9a, and the center block 9 adjacent to the second longitudinal groove 4b in the first axial direction D11 may be defined as the second center block 9b.

[0026] The first center block 9a is point-symmetrical to the second center block 9b with respect to an arbitrary point on the tire equator line L1, and the third center block 9c is point-symmetrical to the fourth center block 9d with respect to an arbitrary point on the tire equator line L1. Note that the first to fourth center blocks 9a to 9d are not limited to the above. For example, the first center block 9a may be asymmetrical to the second center block 9b, and the first center block 9a may be point-symmetrical to the fourth center block 9d with respect to an arbitrary point on the tire equator line L1.

[0027] From the perspective of ensuring the balance of traction performance in multiple directions, among the four groove widths W1 of the first to fourth recesses 91a to 91d, the maximum groove width W1 and the minimum groove width W1 are preferably within the range of ±20% with respect to the average value of the four groove widths W1. Also, from the perspective of ensuring the balance of traction performance in multiple directions, among the four groove lengths L1 of the first to fourth recesses 91a to 91d, the maximum groove length L1 and the minimum groove length L1 are preferably within the range of ±20% with respect to the average value of the four groove lengths L1.

[0028] The first recess 91a and the second recess 91b extend along a direction inclined in one direction (the first axial direction D11) with respect to the tire equator line L1, and the third recess 91c and the fourth recess 91d extend along a direction inclined in the other direction (the second axial direction D12) with respect to the tire equator line L1. By inclining the recess 91 with respect to the tire equator line L1 (the tire circumferential direction D3), traction can be generated in each of the tire axial direction D1 and the tire circumferential direction D3.

[0029] In the present embodiment, the inclination angle of the first recess 91a with respect to the tire equator line L1 is the same as the inclination angle of the second recess 91b with respect to the tire equator line L1, but it is not limited thereto. For example, the inclination angle of the first recess 91a with respect to the tire equator line L1 may be different from the inclination angle of the second recess 91b with respect to the tire equator line L1. The same applies to the third recess 91c and the fourth recess 91d.

[0030] The opening direction of the first recess 91a is opposite to the opening direction of the second recess 91b, and the opening direction of the third recess 91c is opposite to the opening direction of the fourth recess 91d. In the present embodiment, the opening direction of the first recess 91a is along the first circumferential direction D31, and the opening direction of the second recess 91b is along the second circumferential direction D32. And the opening direction of the third recess 91c is along the second axial direction D12, and the opening direction of the fourth recess 91d is along the first axial direction D11.

[0031] The opening direction of the first recess 91a or the second recess 91b preferably forms an angle of 45 degrees to 135 degrees, more preferably an angle of 80 degrees to 100 degrees, with the opening direction of the third recess 91c or the fourth recess 91d. In the present embodiment, the opening direction of the first recess 91a forms an angle of approximately 90 degrees with the opening directions of the third recess 91c and the fourth recess 91d. The same applies to the opening direction of the second recess 91b.

[0032] In the present embodiment, the opening direction of the first recess 91a is parallel to a part of the wall surface of the first center block 9a adjacent to the main groove 2 on the second axis direction D12 side, and the opening direction of the second recess 91b is parallel to a part of the wall surface of the second center block 9b adjacent to the main groove 2 on the first axis direction D11 side. And the opening direction of the third recess 91c is parallel to a part of the wall surface of the third center block 9c adjacent to the first transverse groove 3a, and the opening direction of the fourth recess 91d is parallel to a part of the wall surface of the fourth center block 9d adjacent to the second transverse groove 3b.

[0033] Preferably, one of the first to fourth recesses 91a to 91d opens to one of the pair of main grooves 2, 2, and the other one of the first to fourth recesses 91a to 91d opens to the other of the pair of main grooves 2, 2. In the present embodiment, the third recess 91c opens to the main groove 2 on the second axis direction D12 side, and the fourth recess 91d opens to the main groove 2 on the first axis direction D11 side.

[0034] And still another one of the first to fourth recesses 91a to 91d opens to the transverse groove 3, and the remaining one of the first to fourth recesses 91a to 91d opens to the transverse groove 3 adjacent to the transverse groove 3 in the tire circumferential direction D3. In the present embodiment, the second recess 91b opens to the second transverse groove 3b, and the first recess 91a opens to the first transverse groove 3a.

[0035] Of the first to fourth recesses 91a to 91d, two open to one side in the tire axial direction D1 of the tire equatorial plane S1 and to one side in the tire circumferential direction D3. And the other two of the first to fourth recesses 91a to 91d open to the other side in the tire circumferential direction D3 on the other side in the tire axial direction D1 of the tire equatorial plane S1. In the present embodiment, the first recess 91a and the third recess 91c open to the first circumferential direction D31 side, and the second recess 91b and the fourth recess 91d open to the second circumferential direction D32 side.

[0036] The recess 9 opening into the lateral groove 3 preferably opens to the concave side (convex side of the lateral groove 3) in the tire circumferential direction D3 of the center block 9 from the viewpoint of ensuring the rigidity of the center block 9. In the present embodiment, the first recess 91a opens to the concave side (convex side of the first lateral groove 3a) in the tire circumferential direction D3 of the first center block 9a, and the second recess 91b opens to the concave side (convex side of the second lateral groove 3b) in the tire circumferential direction D3 of the second center block 9b. Note that the opening direction and opening position of the first to fourth recesses 91a to 91d are not limited to the above.

[0037] As shown in FIGS. 2 and 3, the center block 9 includes a stepped portion 92 recessed inward in the tire radial direction D2. According to such a configuration, the traction effect can be improved and the rigidity of the edge portion of the center block 9 can be ensured. In the present embodiment, the stepped portion 92 is disposed on the outer peripheral edge of the center block 9 in contact with the lateral groove 3 and the longitudinal groove 4.

[0038] The center block 9 includes a plurality of sipes 93. The sipes 93 extend linearly or in a bent line shape, but are not limited thereto. The width of the sipes 93 is 1.5 mm or less. The depth of the sipes 93 is smaller than the groove depth of the recess 91. And the sipes 93 include a first sipe 931 opening into the recess 91 and a second sipe 932 not opening (not connected) to the recess 91. One end of the second sipe 932 opens into the lateral groove 3 and the other end is closed or opens into the longitudinal groove 4.

[0039] The first sipe 931 has one end opening at one end of the recess 91 and the other end opening into the main groove 2, the transverse groove 3, or the longitudinal groove 4. That is, the center block 9 is divided by the first sipe 931 which is narrower than the groove width W1 of the recess 91. Thereby, uneven wear of the center block 9 due to providing the recess 91 can be suppressed. The 931 extends in a direction different from that of the recess 91. Thereby, the traction performance of the tire 1 can be improved. And the first sipe 931 extends along the wall surface 911 at one end of the recess 91 and extends parallel to a part of the adjacent transverse groove 3.

[0040] In the present embodiment, in the first center block 9a, the other end of the first sipe 931 opens into the main groove 2 on the second axial direction D12 side, and the other end of the second sipe 932 opens into the first longitudinal groove 4a. In the second center block 9b, the other end of the first sipe 931 opens into the main groove 2 on the first axial direction D11 side, and the other end of the second sipe 932 opens into the first longitudinal groove 4a. In the third and fourth center blocks 9c, 9d, the other end of the first sipe 931 opens into the second longitudinal groove 4b, and the other end of the second sipe 932 is closed. Note that the first sipe 931 and the second sipe 932 are not limited to the above, and are appropriately set in consideration of the tread pattern design, the rigidity of the center block 9, the traction performance, and the like.

[0041] As described above, like in this embodiment, the tire 1 has a pair of main grooves 2 that extend along the tire circumferential direction D3 on both sides of the tire equator line L1 of the tread 13 and partition the tread 13 into three rows of lugs 5, a plurality of transverse grooves 3 that are spaced apart from each other in the tire circumferential direction D3 and extend along the tire axial direction D1 to connect the pair of main grooves 2, and a plurality of longitudinal grooves 4 that extend along the tire circumferential direction D3 between the pair of main grooves 2 to connect the adjacent plurality of transverse grooves 3. Among the three rows of lugs 5, the center lug 6 located between the pair of main grooves 2 repeatedly has four center blocks 9a to 9d partitioned by the transverse grooves 3 and the longitudinal grooves 4 in the tire circumferential direction D3. The four center blocks 9a to 9d each have recesses 91a to 91d that open into the main groove 2, the transverse groove 3, or the longitudinal groove 4 and have one end closed. When the recesses 91a to 91d provided in the four center blocks 9a to 9d are defined as the first to fourth recesses 91a to 91d, the first recess 91a and the second recess 91b extend along a direction inclined in one direction with respect to the tire equator line L1, the third recess 91c and the fourth recess 91d extend along a direction inclined in the other direction with respect to the tire equator line L1, the first recess 91a opens in the opposite direction to the second recess 91b, the third recess 91c opens in the opposite direction to the fourth recess 91d, and it is preferable that the groove width W1 of each of the first to fourth recesses 91a to 91d is 5.0 mm or more.

[0042] According to such a configuration, by making the opening directions of the first to fourth recesses 91a to 91d different from each other and ensuring the groove width W1 of each, the traction performance can be exhibited in a plurality of directions. Thereby, the traction performance of the tire 1 in a plurality of directions can be improved. Further, by closing one end of the recess 91, it is possible to prevent the center block 9 from being divided by the recess 91. Thereby, the rigidity of the center block 9 can be ensured and the traction effect can be exhibited well.

[0043] Also, like the tire 1 according to this embodiment, it is preferable that the opening direction of the first recess 91a or the second recess 91b forms an angle of 45 degrees to 135 degrees with the opening direction of the third recess 91c or the fourth recess 91d.

[0044] According to such a configuration, the opening directions of the first to fourth recesses 91a to 91d can be varied. Thereby, traction can be generated in a well-balanced manner in a plurality of directions.

[0045] Also, like the tire 1 according to the present embodiment, it is preferable that one of the first to fourth recesses 91a to 91d opens to one of the pair of main grooves 2, and the other one of the first to fourth recesses 91a to 91d opens to the other of the pair of main grooves 2.

[0046] According to such a configuration, the water that has entered the recess 91 easily flows into the main groove 2. Thereby, drainage can be efficiently performed from the recess 91 toward the main groove 2, and the drainage performance of the tire 1 can be improved.

[0047] Also, like the tire 1 according to the present embodiment, it is preferable that still another one of the first to fourth recesses 91a to 91d opens to the lateral groove 3, and the remaining one of the first to fourth recesses 91a to 91d opens to the lateral groove 3 adjacent to the lateral groove 3 in the tire circumferential direction D3.

[0048] According to such a configuration, by opening the first to fourth recesses 91a to 91d to different grooves 2 and 3, respectively, the rigidity of the entire four center blocks 9a to 9d can be made closer to being uniform. Thereby, the uneven wear resistance performance of the tire 1 can be enhanced.

[0049] Note that the tire 1 is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described functions and effects. Also, the tire 1 can of course be variously modified within a range not departing from the gist of the present invention. For example, it goes without saying that the configurations and methods according to the following various modification examples can be arbitrarily selected singly or in plurality and adopted in the configurations and methods according to the above-described embodiment.

[0050] In this embodiment, the groove width W1 of the recess 91 is constant from the opening to the wall surface 911 at one end, but it is not limited thereto. For example, the groove width W1 of the recess 91 may extend wider from one end toward the opening. Thereby, water can easily flow in the opening direction of the recess 91, so that the drainage performance of the tire 1 can be improved.

Explanation of Signs

[0051] 1... Tire, 11... Bead portion, 12... Sidewall, 13... Tread, 14... Carcass ply, 15... Inner liner, 2... Main groove, 3... Lateral groove, 3a... First lateral groove, 3b... Second lateral groove, 31... Bend point, 4... Longitudinal groove, 4a... First longitudinal groove, 4b... Second longitudinal groove, 5... Land, 6... Center land, 7... Shoulder land, 71... Shoulder block, 8... Shoulder lateral groove, 9... Center block, 9a... First center block, 9b... Second center block, 9c... Third center block, 9d... Fourth center block, 91... Recess, 911... Wall surface, 91a... First recess, 91b... Second recess, 91c... Third recess, 91d... Fourth recess, 92... Step portion, 93... Sipe, 931... First sipe, 932... Second sipe

Claims

1. A pair of main grooves extending along the tire circumferential direction on both sides of the tire equator line of the tread, partitioning the tread into three rows of land, a plurality of transverse grooves spaced apart from each other in the tire circumferential direction and extending along the tire axial direction, connecting the pair of main grooves, a plurality of longitudinal grooves extending along the tire circumferential direction between the pair of main grooves, connecting the adjacent plurality of transverse grooves, and comprising: Among the three rows of land, the center land located between the pair of main grooves repeats four center blocks partitioned by the transverse grooves and the longitudinal grooves in the tire circumferential direction, Each of the four center blocks is provided with a recess that opens to the main groove, the transverse groove or the longitudinal groove and has one end closed, When the recesses provided in the four center blocks are referred to as first to fourth recesses, the first recess and the second recess extend along a direction inclined in one direction with respect to the tire equator line, and the third recess and the fourth recess extend along a direction inclined in the other direction with respect to the tire equator line, The first recess opens in the opposite direction to the second recess, and the third recess opens in the opposite direction to the fourth recess, The groove width of each of the first to fourth recesses is 5.0 mm or more, When the four center blocks are referred to as first to fourth center blocks, the first center block is point-symmetrical with respect to an arbitrary point on the tire equator line with the second center block, and the third center block is point-symmetrical with respect to an arbitrary point on the tire equator line with the fourth center block, The first center block and the second center block are directly adjacent in the tire axial direction, The third center block and the fourth center block are directly adjacent in the tire axial direction. A pneumatic tire.

2. The pneumatic tire according to claim 1, wherein the opening direction of the first recess or the second recess forms an angle of 45 degrees to 135 degrees with the opening direction of the third recess or the fourth recess.

3. One of the first to fourth recesses opens to one of the pair of main grooves, The pneumatic tire according to claim 1 or 2, wherein the other one of the first to fourth recesses opens to the other one of the pair of main grooves.

4. Still another one of the first to fourth recesses opens to the transverse groove, The pneumatic tire according to claim 3, wherein the remaining one of the first to fourth recesses opens to a transverse groove adjacent to the transverse groove in the tire circumferential direction.

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