Pneumatic tires

Abstract

The present invention relates to a pneumatic tire, which has a pair of main grooves, lateral grooves and longitudinal grooves, and a central land portion with four central pattern blocks repeatedly arranged in the tire circumferential direction, and the four central pattern blocks respectively have a recessed portion that is open in the main groove, the lateral groove or the longitudinal groove and closed at one end. When the recessed portions provided by the four central pattern blocks are set as first to fourth recessed portions, the first recessed portion and the second recessed portion extend in a direction inclined in one direction relative to the tire equator line, and the third recessed portion and the fourth recessed portion extend in a direction inclined in another direction relative to the tire equator line. The first recessed portion opens in a direction opposite to the second recessed portion, and the third recessed portion opens in a direction opposite to the fourth recessed portion. The groove width of each of the first to fourth recessed portions is 5.0 mm or more.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire. Background Art

[0002] For off-road pneumatic tires that are intended to travel on bad roads, including muddy and rocky roads, a tread pattern that mainly includes transverse grooves and pattern blocks with a large number of edge components is generally used. In order to improve the driving performance of such tires, it is desired to obtain traction effects based on the clamping of mud, rocks, etc. on the road surface in multiple directions. In addition, in terms of improving the traction effect, it is key to ensure the rigidity of the pattern blocks.

[0003] Patent document 1 discloses a pneumatic tire for off-road use, which includes: a pair of main grooves extending in the tire circumferential direction; a lateral groove connecting the pair of main grooves; a longitudinal groove connecting adjacent lateral grooves in the tire circumferential direction; and a plurality of central pattern blocks divided by the pair of main grooves, the lateral grooves, and the longitudinal grooves. The central pattern blocks are provided with: a narrow groove opening in the main groove; and a recess opening in the lateral groove, and the opening directions of the grooves are different.

[0004] However, in Patent Document 1, the narrow grooves opening into the main grooves have a smaller groove width and the same influence on the block rigidity and groove area as the sipes, and therefore, the traction effect due to the clamping of mud, rocks, etc. is hardly considered.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-1664 Summary of the invention

[0008] An object of the present invention is to provide a pneumatic tire that can exert traction effects in multiple directions.

[0009] The pneumatic tire of the present invention comprises: a pair of main grooves extending in the tire circumferential direction on both sides of the tire equator of the tread portion and dividing the tread portion into three rows of land portions; a plurality of lateral grooves extending in the tire axial direction in a manner separated from each other in the tire circumferential direction and connecting the pair of main grooves; and a plurality of longitudinal grooves extending in the tire circumferential direction between the pair of main grooves and connecting adjacent plurality of lateral grooves, wherein in the three rows of land portions, a central land portion located between the pair of main grooves is repeatedly provided with four central pattern blocks divided by the lateral grooves and the longitudinal grooves in the tire circumferential direction, and the four central pattern blocks are The pattern blocks are respectively provided with a recessed portion which is open in the main groove, the lateral groove or the longitudinal groove and is closed at one end. When the recessed portions provided in the four central pattern blocks are set as the first to fourth recessed portions, the first recessed portion and the second recessed portion extend in a direction inclined in one direction relative to the tire equator line, and the third recessed portion and the fourth recessed portion extend in a direction inclined in another direction relative to the tire equator line. The first recessed portion opens in a direction opposite to the second recessed portion, and the third recessed portion opens in a direction opposite to the fourth recessed portion. The groove width of each of the first to fourth recessed portions is greater than 5.0 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view of a tire meridian plane of a pneumatic tire according to one embodiment.

[0011] Figure 2 It is a perspective view showing a main part of the pneumatic tire according to this embodiment.

[0012] Figure 3 It is a diagram showing a tread pattern of a pneumatic tire according to this embodiment.

[0013] Description of Reference Numerals

[0014] 1…tire; 11…bead portion; 12…sidewall portion; 13…tread portion; 14…carcass cord; 15…inner liner; 2…main groove; 3…lateral groove; 3a…first lateral groove; 3b…second lateral groove; 31…bending point; 4…longitudinal groove; 4a…first longitudinal groove; 4b…second longitudinal groove; 5…land portion; 6…central land portion; 7…shoulder land portion; 71…shoulder block; 8…shoulder lateral groove; 9…central block; 9a…first central block; 9b…second central block; 9c…third central block; 9d…fourth central 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. DETAILED DESCRIPTION

[0015] Below, refer to Figure 1 to Figure 3One embodiment of a pneumatic tire will be described. In addition, in each drawing, the dimensional ratio in the drawing does not necessarily match the actual dimensional ratio, and the dimensional ratio between the drawings does not necessarily match.

[0016] 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 referred to as "tire") 1, the second direction D2 is the tire radial 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.

[0017] In the tire axial direction D1, the inner side is the side close to the tire equatorial plane S1, and the outer side is the side away from the tire equatorial plane S1. In the tire radial direction D2, the inner side is the side close to the tire rotation axis, and the outer side is the side away from the tire rotation axis. In addition, one direction of the tire axial direction D1 is referred to as the first axial direction D11, and the opposite direction of the first axial direction D11 is referred to as the second axial direction D12. One direction of the tire circumferential direction D3 is referred to as the first circumferential direction D31, and the opposite direction of the first circumferential direction D31 is referred to as the second circumferential direction D32.

[0018] The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and is located at the center of the tire axial direction D1 of the tire 1. The tire meridian plane is a plane including the tire rotation axis and is perpendicular to the tire equatorial plane S1. In addition, the tire equatorial line L1 is a line intersecting the outer surface of the tire 1 in the tire radial direction D2 and the tire equatorial plane S1.

[0019] like Figure 1 As shown, the tire 1 includes: a pair of bead portions 11, 11; a pair of sidewall portions 12, 12 extending from each bead portion 11, 11 toward the outside of the tire radial direction D2; a tread portion 13 connected to the outer ends of the pair of sidewall portions 12, 12 in the tire radial direction D2; a carcass cord 14 extending in a manner of being spanned between the pair of bead portions 11, 11; and an inner liner 15 located at the innermost side of the tire 1. The tire 1 involved in this embodiment is an off-road tire for the purpose of running on bad roads including muddy land and rocky land, but is not limited thereto.

[0020] like Figure 2 and Figure 3 As shown, the tire 1 includes: a pair of main grooves 2, 2 extending continuously along the tire circumferential direction D3 on both sides of the tire equator line L1 of the tread portion 13; a plurality of lateral grooves 3 connecting the pair of main grooves 2; and a plurality of longitudinal grooves 4 connecting adjacent plural lateral grooves 3. From the viewpoint of exerting a traction effect, it is preferred that the main grooves 2 extend in a zigzag curved shape.

[0021] The plurality of lateral grooves 3 are separated from each other in the tire circumferential direction D3. Moreover, the lateral grooves 3 extend along the tire axial direction D1. From the viewpoint of exerting traction effect in multiple directions, it is preferred that the lateral grooves 3 are inclined relative to the tire axial direction D1. In the present embodiment, the groove depth of the lateral grooves 3 is the same as the groove depth of the main grooves 2.

[0022] The lateral groove 3 has a bending point 31. As a result, the edge component of the central pattern block 9 described later can be increased, thereby improving the traction performance of the tire 1. The lateral grooves 3, 3 adjacent to each other in the tire circumferential direction D3 are respectively referred to as the first lateral groove 3a and the second lateral groove 3b. Moreover, the bending point 31 of each lateral groove 3a, 3b is respectively referred to as the first bending point 31a and the second bending point 31b. 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. In addition, the lateral groove 3 is not limited to this.

[0023] The longitudinal groove 4 extends along the tire circumferential direction D3 between the pair of main grooves 2. Moreover, 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 traction effect in multiple directions, it is preferred that the longitudinal groove 4 is inclined relative 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 approximately perpendicularly (80 to 100 degrees).

[0024] The longitudinal groove 4 extending from the second transverse groove 3b toward one side of the tire circumferential direction D3 is called the first longitudinal groove 4a, and the longitudinal groove 4 extending from the transverse groove 3 toward the other side of the tire circumferential direction D3 is called the second longitudinal groove 4b. The first longitudinal groove 4a and the second longitudinal groove 4b are configured to be 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 in a straight line, and the second longitudinal groove 4b is formed in an approximately Z-shape. Moreover, the groove depth of the longitudinal groove 4 is the same as the groove depth of the main groove 2 and the transverse groove 3. In addition, the longitudinal groove 4 is not limited to this.

[0025] The tread portion 13 includes three rows of land portions 5 divided by a pair of main grooves 2. The three rows of land portions 5 include: a central land portion 6 located between the pair of main grooves 2; and a pair of shoulder land portions 7, 7 located outside the main grooves 2 in the tire axial direction D1. In addition, the tire 1 includes shoulder lateral grooves 8 extending from the main grooves 2 to the outside in the tire axial direction D1. The shoulder land portion 7 is divided into a plurality of shoulder pattern blocks 71 by the shoulder lateral grooves 8.

[0026] like Figure 3As shown, the central land portion 6 includes a plurality of central blocks 9 divided by the lateral grooves 3, the first longitudinal grooves 4a, and the second longitudinal grooves 4b. The central land portion 6 is formed by repeatedly arranging four central blocks 9 (first to fourth central blocks 9a to 9d described later) adjacent to each other in the tire circumferential direction D3. The shape of the central block 9 is determined by the shapes of the main grooves 2, the lateral grooves 3, the first longitudinal grooves 4a, and the second longitudinal grooves 4b.

[0027] The central pattern block 9 has a recess 91 which is open to any one of the main groove 2, the lateral groove 3, the first longitudinal groove 4a or the second longitudinal groove 4b and is closed at one end. One recess 91 is arranged for one central pattern block 9. In the present embodiment, the recess 91 is formed in a straight line. The wall surface 911 at one end of the recess 91 is inclined relative to the opening direction and is parallel to a portion of the adjacent lateral groove 3 in the opposite direction (closing direction) to the opening direction of the recess 91. In addition, the recess 91 is not limited to this. The opening direction of the recess 91 refers to the direction from the wall surface 911 toward the opening position of the recess 91 and is the direction along the central axis of the recess 91.

[0028] 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 equal to the groove width W2 of the main groove 2 (see Figure 1 ). This is because the groove width W1 of the recessed portion 91 is set to be 50% or more of the groove width W2 of the main groove 2 to improve the traction effect, and the groove width W1 of the recessed portion 91 is set to be 70% or less of the groove width W2 of the main groove 2 to ensure the rigidity of the central pattern block 9. In addition, from the viewpoint of ensuring the rigidity of the central pattern block 9 and exerting the traction effect, it is preferred that the recessed portion 91 extends from the opening position with a constant groove width W1.

[0029] From the viewpoint of exerting the traction effect, the groove length L1 of the recessed portion 91 is preferably greater than the groove width W1 of the recessed portion 91. Furthermore, from the viewpoint of ensuring the rigidity of the central block 9 and exerting the traction effect, the groove length L1 of the recessed portion 91 is preferably 30% to 70% of the length L2 from the opening position of the recessed portion 91 to the end of the central block 9 intersecting on the extension line of the recessed portion 91.

[0030] From the viewpoint of ensuring wear resistance, the groove depth of the recessed portion 91 is preferably 40% or more of the groove depth of the main groove 2. In the present embodiment, the groove depth of the recessed portion 91 is the same as the groove depth of the main groove 2, the lateral groove 3, and the longitudinal groove 4, but the present invention is not limited thereto. For example, the groove depth of the recessed portion 91 may be smaller than the groove depth 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 recessed portion 91 are appropriately set according to the appearance of the tread pattern, the rigidity of the tread block, the traction performance, the drainage performance, and the like.

[0031] Here, the central block 9 adjacent to the first longitudinal groove 4a in the second axial direction D12 is set as the first central block 9a, the central block 9 adjacent to the first longitudinal groove 4a in the first axial direction D11 is set as the second central block 9b, the central block 9 adjacent to the second longitudinal groove 4b in the second axial direction D12 is set as the third central block 9c, and the central block 9 adjacent to the second longitudinal groove 4b in the first axial direction D11 is set as the fourth central block 9d. In addition, the recessed portions 91 respectively provided in the first to fourth central blocks 9a, 9b, 9c, and 9d are set as the first to fourth recessed portions 91a to 91d. In addition, the lateral groove 3 intersecting the first longitudinal groove 4a on the first circumferential direction D31 side (intersecting the second longitudinal groove 4b on the second circumferential direction D32 side) is set as the first lateral groove 3a, and the lateral groove 3 intersecting the first longitudinal groove 4a on the second circumferential direction D32 side (intersecting the second longitudinal groove 4b on the first circumferential direction D31 side) is set as the second lateral groove 3b. In addition, the first to fourth central blocks 9a, 9b, 9c, 9d are not limited to the above positions. For example, the central block 9 adjacent to the first longitudinal groove 4a in the first axial direction D11 may be set as the first central block 9a, and the central block 9 adjacent to the second longitudinal groove 4b in the first axial direction D11 may be set as the second central block 9b.

[0032] The first central block 9a and the second central block 9b are point-symmetrical with respect to any point on the tire equator line L1, and the third central block 9c and the fourth central block 9d are point-symmetrical with respect to any point on the tire equator line L1. In addition, the first to fourth central blocks 9a to 9d are not limited thereto. For example, the first central block 9a may not be symmetrical with the second central block 9b, and the first central block 9a may be point-symmetrical with the fourth central block 9d with respect to any point on the tire equator line L1.

[0033] From the viewpoint of ensuring a balance in traction performance in multiple directions, it is preferred that 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 each set within a range of ±20% relative to the average value of the four groove widths W1. In addition, from the viewpoint of ensuring a balance in traction performance in multiple directions, it is preferred that 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 each set within a range of ±20% relative to the average value of the four groove lengths L1.

[0034] The first recess 91a and the second recess 91b extend in a direction inclined in one direction (first axial direction D11) relative to the tire equator line L1, and the third recess 91c and the fourth recess 91d extend in a direction inclined in another direction (second axial direction D12) relative to the tire equator line L1. The recess 91 is inclined relative to the tire equator line L1 (tire circumferential direction D3) to generate traction in the tire axial direction D1 and the tire circumferential direction D3.

[0035] 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 the present invention 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 is true for the third recess 91c and the fourth recess 91d.

[0036] 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 this 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. Moreover, 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.

[0037] Preferably, the opening direction of the first recess 91a or the second recess 91b is formed at an angle of 45 to 135 degrees relative to the opening direction of the third recess 91c or the fourth recess 91d, and more preferably at an angle of 80 to 100 degrees. In the present embodiment, the opening direction of the first recess 91a is approximately formed at an angle of about 90 degrees with the opening directions of the third recess 91c and the fourth recess 91d. The same is true for the opening direction of the second recess 91b.

[0038] In the present embodiment, the opening direction of the first recess 91a is parallel to a portion of the wall surface of the first center block 9a adjacent to the main groove 2 on the second axial direction D12 side, and the opening direction of the second recess 91b is parallel to a portion of the wall surface of the second center block 9b adjacent to the main groove 2 on the first axial direction D11 side. Furthermore, the opening direction of the third recess 91c is parallel to a portion of the wall surface of the third center block 9c adjacent to the first lateral groove 3a, and the opening direction of the fourth recess 91d is parallel to a portion of the wall surface of the fourth center block 9d adjacent to the second lateral groove 3b.

[0039] Preferably, one of the first to fourth recesses 91a to 91d opens in one of the pair of main grooves 2, 2, and the other of the first to fourth recesses 91a to 91d opens in the other of the pair of main grooves 2, 2. In the present embodiment, the third recess 91c opens in the main groove 2 on the second axial direction D12 side, and the fourth recess 91d opens in the main groove 2 on the first axial direction D11 side.

[0040] Furthermore, another one of the first to fourth recesses 91a to 91d opens in the lateral groove 3, and the remaining one of the first to fourth recesses 91a to 91d opens in the lateral groove 3 adjacent to the lateral groove 3 in the tire circumferential direction D3. In the present embodiment, the second recess 91b opens in the second lateral groove 3b, and the first recess 91a opens in the first lateral groove 3a.

[0041] Two of the first to fourth recesses 91a to 91d are open on one side of the tire axial direction D1 of the tire equatorial plane S1 toward one side of the tire circumferential direction D3. Moreover, the other two of the first to fourth recesses 91a to 91d are open on the other side of the tire axial direction D1 of the tire equatorial plane S1 toward the other side of the tire circumferential direction D3. In the present embodiment, the first recess 91a and the third recess 91c are open toward the first circumferential direction D31, and the second recess 91b and the fourth recess 91d are open toward the second circumferential direction D32.

[0042] From the viewpoint of ensuring the rigidity of the center block 9, it is preferred that the recessed portion 91 opening in the lateral groove 3 opens toward the concave side of the center block 9 in the tire circumferential direction D3 (the convex side of the lateral groove 3). In the present embodiment, the first recessed portion 91a opens toward the concave side of the first center block 9a in the tire circumferential direction D3 (the convex side of the first lateral groove 3a), and the second recessed portion 91b opens toward the concave side of the second center block 9b in the tire circumferential direction D3 (the convex side of the second lateral groove 3b). In addition, the opening directions and opening positions of the first to fourth recessed portions 91a to 91d are not limited thereto.

[0043] like Figure 2 and Figure 3 As shown in FIG. 1 , the center block 9 has a stepped portion 92 that is recessed inward in the tire radial direction D2. According to such a structure, the traction effect can be improved and the rigidity of the edge of the center block 9 can be ensured. In the present embodiment, the stepped portion 92 is arranged at the outer peripheral edge of the center block 9 that contacts the lateral groove 3 and the longitudinal groove 4.

[0044] The central pattern block 9 includes a plurality of sipes 93. The sipes 93 extend in a straight line or a curved line, but are not limited thereto. The width of the sipes 93 is 1.5 mm or less. The depth of the sipes 93 is less than the groove depth of the recess 91. In addition, the sipes 93 include: a first sipe 931 that opens in the recess 91; and a second sipe 932 that does not open (is not connected) in the recess 91. One end of the second sipe 932 opens in the lateral groove 3, and the other end is closed or opens in the longitudinal groove 4.

[0045] One end of the first sipe 931 opens at one end of the recess 91, and the other end opens at the main groove 2, the lateral groove 3, or the longitudinal groove 4. That is, the central pattern block 9 is divided by the first sipe 931 having a width smaller than the groove width W1 of the recess 91. Thus, the uneven wear of the central pattern block 9 can be suppressed by providing the recess 91. The sipe 931 extends in a direction different from the recess 91. Thus, the traction performance of the tire 1 can be improved. Furthermore, the first sipe 931 extends along the wall surface 911 at one end of the recess 91 and extends in parallel with a portion of the adjacent lateral groove 3.

[0046] In the present embodiment, regarding the first central pattern block 9a, the other end of the first sipe 931 opens in the main groove 2 on the second axial direction D12 side. The other end of the second sipe 932 opens in the first longitudinal groove 4a. Regarding the second central pattern block 9b, the other end of the first sipe 931 opens in the main groove 2 on the first axial direction D11 side, and the other end of the second sipe 932 opens in the first longitudinal groove 4a. Regarding the third and fourth central pattern blocks 9c and 9d, the other end of the first sipe 931 opens in the second longitudinal groove 4b, and the other end of the second sipe 932 is closed. In addition, the first sipe 931 and the second sipe 932 are not limited to this, and are appropriately set in consideration of the aesthetic appearance of the tread pattern, the rigidity of the central pattern block 9, the traction performance, etc.

[0047] As described above, as in the present embodiment, the following structure is preferred, wherein the tire 1 comprises: a pair of main grooves 2 extending along the tire circumferential direction D3 on both sides of the tire equator line L1 of the tread portion 13 and dividing the tread portion 13 into three rows of land portions 5; a plurality of lateral grooves 3 extending along the tire axial direction D1 in a manner separated from each other in the tire circumferential direction D3 and connecting the pair of main grooves 2; and a plurality of longitudinal grooves 4 extending along the tire circumferential direction D3 between the pair of main grooves 2 and connecting adjacent plurality of lateral grooves 3, wherein in the three rows of land portions 5, a central land portion 6 located between the pair of main grooves 2 is repeatedly provided with four central pattern blocks 9a to 9d divided by the lateral grooves 3 and the longitudinal grooves 4 in the tire circumferential direction D3, and the four central pattern blocks 9a to 9d are divided into The tire treads are provided with recesses 91a to 91d which are opened in the main groove 2, the lateral groove 3 or the longitudinal groove 4 and are closed at one end. When the recesses 91a to 91d provided in the four central pattern blocks 9a to 9d are set as the first to fourth recesses 91a to 91d, the first recess 91a and the second recess 91b extend in a direction inclined in one direction relative to the tire equator line L1, and the third recess 91c and the fourth recess 91d extend in a direction inclined in another direction relative to the tire equator line L1. The first recess 91a opens in a direction opposite to the second recess 91b, and the third recess 91c opens in a direction opposite to the fourth recess 91d. The groove width W1 of each of the first to fourth recesses 91a to 91d is 5.0 mm or more.

[0048] According to the above structure, the opening directions of the first to fourth recesses 91a to 91d are different, and the groove width W1 of each is ensured, so that traction performance can be exerted in multiple directions. As a result, the traction performance of the tire 1 in multiple directions can be improved. In addition, only one end of the recess 91 is closed to prevent the central block 9 from being divided by the recess 91. As a result, the rigidity of the central block 9 can be ensured and the traction effect can be well exerted.

[0049] In addition, as in the tire 1 according to the present embodiment, it is preferable that the opening direction of the first recess 91a or the second recess 91b and the opening direction of the third recess 91c or the fourth recess 91d form an angle of 45 to 135 degrees.

[0050] According to the above configuration, the opening directions of the first to fourth recesses 91a to 91d can be made different, thereby generating pulling forces in a balanced manner in multiple directions.

[0051] In addition, as in the tire 1 involved in this embodiment, the following structure is preferred, in which one of the first to fourth recesses 91a to 91d opens in one main groove 2 of a pair of main grooves 2, and the other one of the first to fourth recesses 91a to 91d opens in the other main groove 2 of the pair of main grooves 2.

[0052] According to the above configuration, water entering the recessed portion 91 easily flows toward the main groove 2. Thus, water can be efficiently discharged from the recessed portion 91 toward the main groove 2, and the drainage performance of the tire 1 can be improved.

[0053] In addition, as in the tire 1 involved in this embodiment, it is preferable to have a structure in which another one of the first to fourth recesses 91a to 91d opens in the lateral groove 3, and the remaining one of the first to fourth recesses 91a to 91d opens in the lateral groove 3 adjacent to the lateral groove 3 in the tire circumferential direction D3.

[0054] According to the above configuration, the first to fourth recesses 91a to 91d are opened in different grooves 2 and 3, so that the rigidity of the four center blocks 9a to 9d as a whole can be uniformly close.

[0055] In addition, the tire 1 is not limited to the structure of the above-mentioned embodiment, nor is it limited to the above-mentioned effects. In addition, various changes can be made to the tire 1 without departing from the scope of the present invention. For example, any one or more of the structures, methods, etc. involved in the following various modification examples can be selected, and the structures, methods, etc. involved in the above-mentioned embodiment can also be adopted.

[0056] In the present embodiment, the groove width W1 of the recess 91 is constant from the opening to the wall surface 911 at one end, but the present invention is not limited thereto. For example, the recess 91 may extend in a manner such that the groove width W1 increases from one end toward the opening. Thus, water easily flows toward the opening of the recess 91, thereby improving the drainage performance of the tire 1.

Claims

1. A pneumatic tire, characterized in that: The pneumatic tire has: a pair of main grooves extending in the tire circumferential direction on both sides of the tire equator of the tread portion and dividing the tread portion into three rows of land portions; a plurality of lateral grooves extending in the tire axial direction and spaced apart from each other in the tire circumferential direction and connecting the pair of main grooves; and a plurality of longitudinal grooves extending in the tire circumferential direction between the pair of main grooves and connecting the plurality of adjacent lateral grooves; In the three rows of land portions, a central land portion located between the pair of main grooves has four central blocks divided by the lateral grooves and the longitudinal grooves repeatedly arranged in the tire circumferential direction. The four central blocks each include a concave portion that opens in the main groove, the lateral groove or the longitudinal groove and is closed at one end. When the recessed portions provided in the four center blocks are set as first to fourth recessed portions, the first recessed portion and the second recessed portion extend in a direction inclined in one direction relative to the tire equator line, and the third recessed portion and the fourth recessed portion extend in a direction inclined in another direction relative to the tire equator line. The first recess opens in a direction opposite to the second recess, and the third recess opens in a direction opposite to the fourth recess. The groove width of each of the first to fourth recesses is 5.0 mm or more, When the four central blocks are set as the first to fourth central blocks, the first central block and the second central block are point symmetrical with respect to any point on the tire equator, and the third central block and the fourth central block are point symmetrical with respect to any point on the tire equator. The first central pattern block and the second central pattern block are directly adjacent to each other in the tire axial direction. The third central pattern block is directly adjacent to the fourth central pattern block in the tire axial direction.

2. The pneumatic tire according to claim 1, characterized in that 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. The pneumatic tire according to claim 1 or 2, characterized in that: One of the first to fourth recesses opens into one of the pair of main grooves, The other one of the first to fourth recessed portions opens into the other main groove of the pair of main grooves.

4. The pneumatic tire according to claim 3, characterized in that: Another one of the first to fourth recesses opens into the transverse groove, The remaining one of the first to fourth recessed portions opens into a lateral groove adjacent to the lateral groove in the tire circumferential direction.

5. The pneumatic tire according to claim 1 or 2, characterized in that: The groove width of the concave portion is 50% to 70% of the groove width of the main groove.

6. The pneumatic tire according to claim 1 or 2, characterized in that: The groove length of the recessed portion is greater than the groove width of the recessed portion.

7. The pneumatic tire according to claim 6, characterized in that: The groove length of the recessed portion is 30% to 70% of the length from the opening position of the recessed portion to the end of the center block intersecting on the extended line of the recessed portion.

8. The pneumatic tire according to claim 1 or 2, characterized in that: The first recessed portion and the second recessed portion extend in a direction inclined in one direction with respect to the tire equator line. The third recessed portion and the fourth recessed portion extend in a direction inclined in another direction with respect to the tire equator.

9. The pneumatic tire according to claim 8, characterized in that: The first recess and the third recess are open on one side of the tire axial direction of the tire equator toward one side of the tire circumferential direction. The second recess and the fourth recess open toward the other side in the tire circumferential direction on the other side of the tire equator in the tire axial direction.

10. The pneumatic tire according to claim 4, wherein: The recessed portion, among the first to fourth recessed portions, which opens into the lateral groove, opens toward the concave side of the center block in the tire circumferential direction.

11. The pneumatic tire according to claim 1, wherein: The central pattern block has a stepped portion that is recessed inwardly in the tire radial direction. The step portion is arranged on an outer peripheral edge of the center block that is in contact with the lateral groove and the longitudinal groove.

12. The pneumatic tire according to claim 1, wherein: The central land portion is formed by repeatedly arranging only the four central blocks in the tire circumferential direction.

13. The pneumatic tire according to claim 1, wherein: One of the central pattern blocks is directly adjacent to the other three central pattern blocks.

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