JP5346664B2 - tire - Google Patents

Description

  The present invention relates to a tire including a plurality of ribs extending along the tire circumferential direction, and having a narrow groove extending along the tire circumferential direction formed on a rib located in an outer region of the tread in the tread width direction.

  Conventionally, in tires mounted on automobiles, the rigidity of the central portion and shoulder portion of the tread is different, so that the central portion and the shoulder portion do not wear uniformly, and either the central portion or the shoulder portion wears more. Wear may occur. Therefore, various methods are used to suppress such uneven wear.

  For example, by forming a narrow groove extending along the tire circumferential direction in the shoulder part that is wider in the tread width direction and higher in rigidity than the center part, the rigidity of the shoulder part is suppressed, and sudden deceleration during straight traveling, etc. Uneven wear due to input from the tire circumferential direction can be suppressed.

  In a tire in which such a narrow groove is formed, there is a concern that a so-called stone bite, in which pebbles or the like bite into the fine groove during running, may cause a crack in the tread due to the bited pebbles. Therefore, in order to suppress the occurrence of stone biting, a method of forming a narrow groove having a gradually increased width in the tread width direction from the inner side to the outer side in the tire radial direction in the vicinity of the surface of the tread is widely known (for example, Patent Document 1).

Japanese Patent Laid-Open No. 5-278414 (page 3-4, FIG. 2)

  However, the conventional tire described above has the following problems. That is, in the conventional tire in which a narrow groove is formed along the tire circumferential direction in the shoulder portion having higher rigidity than the central portion in order to suppress the difference in rigidity between the central portion and the shoulder portion and to wear the tread uniformly. There is a problem that the bending rigidity with respect to a large load is not sufficient. In such a tire, when a large load is applied to the tire, a so-called buckling in which the tread located in the center in the tread width direction warps inward in the tire radial direction may occur.

  Since the above-mentioned narrow groove is formed in the shoulder portion located on the outer side in the tread width direction than the center portion, the tire equator from the inner side to the outer side in the tire radial direction in the cross section along the tread width direction and the tire radial direction. Inclined to the line side. Therefore, the narrow groove has a problem that it is difficult to discharge pebbles once bitten.

  Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a tire that can further suppress the occurrence of stone biting while suppressing the occurrence of uneven wear.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention includes a plurality of ribs (central rib A1, shoulder rib A2, shoulder rib A3) extending along the tire circumferential direction (tire circumferential direction R), and the width of the tread (tread 40). A tire (pneumatic tire 1) in which narrow ribs (for example, narrow grooves 10) extending along the tire circumferential direction are formed in the ribs (shoulder ribs A2 and shoulder ribs A3) located on the shoulder portion on the outer side in the direction. In the cross section along the tread width direction (tread width direction W) and the tire radial direction (tire radial direction D), the center line (center line CL1) in the tread width direction of the narrow groove is the inner side from the outer side in the tire radial direction. The gist is to incline toward the tire equator line.

  According to such a tire, a narrow groove is formed in the rib located in the shoulder portion on the outer side in the width direction of the tread, and the tread width direction of the narrow groove in the cross section of the tire along the tread width direction and the tire radial direction. The center line of inclines toward the tire equator line side from the outer side in the tire radial direction toward the inner side.

  When a heavy load is applied to such a tire and buckling occurs, the narrow groove formed in the rib located on the shoulder portion on the outer side in the width direction of the tread is directed toward the tire equator line side from the inner side to the outer side in the tire radial direction. Tilt.

  That is, in the cross section of the tire along the tread width direction and the tire radial direction, the center line of the narrow groove inclined toward the tire equator line side from the outer side to the inner side in the tire radial direction is And deform to be orthogonal. For this reason, the pebbles caught in the narrow groove 10 are easily discharged along with the rolling of the tire.

  Therefore, according to such a tire, it is possible to provide a tire that can further suppress the occurrence of stone biting while suppressing the occurrence of uneven wear.

  The second feature of the present invention is related to the first feature of the present invention, wherein the narrow groove is formed to have a wider width along the tread width direction than the other narrow grooves (for example, the minor groove 12A). The sub-groove includes an outer groove portion (outer groove portion 20A) formed along the tire radial direction from the surface of the tread, and an inner groove portion (inner groove portion) that is continuous with the outer groove portion and located on the inner side in the tire radial direction than the outer groove portion. The area (area S2) of the inner groove portion in the tread surface view is smaller than the area (area S1) of the outer groove portion.

  The third feature of the present invention is related to the second feature of the present invention, wherein the outer groove portion is opposed to the first outer surface portion (first outer surface portion 22A) extending along the tire radial direction, and the first outer surface portion, The second outer surface portion (second outer surface portion 22B) extending along the tire radial direction, the inner groove portion is connected to the first outer surface portion, protrudes to the inner groove portion from the first outer surface portion, and the tire diameter A first inner wall portion (first inner wall portion 31A) extending along the direction, facing the first inner wall portion, continuing to the second outer surface portion, protruding to the inside of the inner groove portion from the second outer surface portion, The bottom (second inner wall 31B) extending along the tire radial direction and the bottom of the inner groove, the first inner wall and the second inner wall, the bottom extending along the tire circumferential direction ( And the bottom 34).

  A fourth feature of the present invention relates to the third feature of the present invention, wherein the first inner wall portion and the second inner wall portion are wall upper surfaces (wall upper surface 36A, wall upper surface 36B) substantially parallel to the surface of the tread. And a side surface (side surface 32A, side surface 32B) that extends from the wall top surface to the bottom along the tire radial direction and the tire circumferential direction.

  A fifth feature of the present invention relates to the fourth feature of the present invention, and is along the tire radial direction from the surface of the tread to the outer ends in the tire radial direction of the first inner wall portion and the second inner wall portion. The distance (distance L1) is shorter than the width (width L2) along the tread width direction of the outer groove portion on the surface of the tread, and is the distance (distance) from the side surface of the first inner wall portion to the side surface of the second inner wall portion. The gist is that it is longer than L3).

  According to the features of the present invention, it is possible to provide a tire that can further suppress the occurrence of stone biting while suppressing the occurrence of uneven wear.

It is an expanded view of the tread of the pneumatic tire concerning a 1st embodiment of the present invention. It is a perspective view of the narrow groove concerning a 1st embodiment of the present invention. It is sectional drawing of the tire radial direction of the narrow groove concerning 1st Embodiment of this invention. It is sectional drawing of the tire radial direction of the minor groove which concerns on 1st Embodiment of this invention. It is a perspective view of the narrow groove concerning a 2nd embodiment of the present invention. It is sectional drawing of the tire radial direction of the minor groove which concerns on 2nd Embodiment of this invention. It is the tread surface view of the subgroove which concerns on 2nd Embodiment of this invention. It is sectional drawing of the tire radial direction of the narrow groove concerning other embodiment of this invention.

  Next, first and second embodiments, comparative evaluation, and other embodiments of the tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  In the present embodiment, (1) tire configuration, (2) narrow groove configuration, and (3) operation and effect will be described.

(1) Configuration of Tire FIG. 1 is a development view of a tread constituting the pneumatic tire 1 according to the first embodiment of the present invention. The pneumatic tire 1 includes a plurality of ribs extending along the tire circumferential direction R. Specifically, the pneumatic tire 1 includes a central rib A1, a shoulder rib A2, and a shoulder rib A3. In the pneumatic tire 1, a circumferential groove 110, a circumferential groove 112, and a circumferential groove 114 extending along the tire circumferential direction R are formed between the plurality of ribs. The shoulder rib A2 and the shoulder rib A3 are located on the shoulder portion on the outer side in the tread width direction W in the tread width direction W.

  A lateral groove 120 extending along the tread width direction W is formed in the central rib A1. The lateral groove 120 communicates with the circumferential groove and terminates in the central rib A1.

  A hole 50, a narrow groove 10, and a lateral groove 122 are formed in the shoulder rib A2 and the shoulder rib A3. A plurality of holes 50 are formed in the tread 40 along the tire circumferential direction R. The hole 50 is recessed inward in the tire radial direction from the surface of the tread 40 that contacts the road surface. The narrow groove 10 extends along the tire circumferential direction R.

(2) Structure of narrow groove The structure of a narrow groove is demonstrated. Specifically, (2.1) Detailed configuration of the narrow groove and (2.2) Detailed configuration of the sub-groove will be described with reference to FIGS. FIG. 2 is a perspective view of the narrow groove according to the first embodiment of the present invention. FIG. 3 is a sectional view in the tire radial direction of the narrow groove according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view in the tire radial direction of the minor groove according to the first embodiment of the present invention.

(2.1) Detailed configuration of narrow groove As shown in FIGS. 2 and 3, the center line of the narrow groove 10 in the tread width direction W in the cross section of the pneumatic tire 1 along the tread width direction W and the tire radial direction D. CL1 is inclined toward the tire equator line CL side from the outside in the tire radial direction toward the inside, that is, in the present embodiment, the vehicle inside. Specifically, the inclination angle θ1 formed by the center line CL1 of the narrow groove 10 and the straight line CL2 along the tire radial direction D is set to be greater than 0 degree and 20 degrees or less. In the present embodiment, the inclination angle θ1 is set to 5 degrees. In addition, when the inclination angle θ1 is larger than 20 degrees, in the manufacturing process of the pneumatic tire 1, the narrow groove 10 is extremely undercut, and there is a concern that chipping may occur when being extracted from the mold. .

  In the cross section along the tread width direction W and the tire radial direction D, the shoulder rib A2 and the shoulder rib A3 include a groove portion 20 that forms the narrow groove 10 along the tire radial direction D. The groove portion 20 is inclined toward the tire equator line CL side from the outer side in the tire radial direction toward the inner side. The width of the narrow groove 10 along the direction orthogonal to the center line CL1 is defined as a groove width W1.

(2.2) Detailed Configuration of Sub-groove As shown in FIGS. 2 and 4, the narrow groove 10 includes a sub-groove 12 having a wider width along the tread width direction W than the other narrow grooves 10. As shown in FIG. 4, in the cross section of the pneumatic tire 1 along the tread width direction W and the tire radial direction D, the center line CL <b> 1 in the tread width direction W of the sub-groove 12 is the tire equator, like the narrow groove 10. Inclined toward the line CL. Specifically, the inclination angle θ1 formed by the center line CL1 of the sub-groove 12 and the straight line CL2 along the tire radial direction D is set to be larger than 0 degree and 20 degrees or less. In the present embodiment, the inclination angle θ1 is set to 5 degrees.

  In the cross section along the tread width direction W and the tire radial direction D, the shoulder rib A2 and the shoulder rib A3 include a groove portion 22 that forms the secondary groove 12 along the tire radial direction D. The groove portion 22 is inclined toward the tire equator line CL side from the outer side in the tire radial direction toward the inner side. The width of the sub-groove 12 along the direction orthogonal to the center line CL1 is defined as a groove width W2. The groove width W2 is wider than the groove width W1.

(3) Actions / Effects As described above, according to the pneumatic tire 1 according to the present embodiment, the shoulder rib A2 and the shoulder rib A3 located on the outer side of the tread along the tread width direction W have narrow grooves. In the cross section of the tire along the tread width direction W and the tire radial direction D, the center line CL1 in the tread width direction W of the narrow groove 10 is the tire equator line CL side from the tire radial direction outer side to the inner side. Inclined to.

  When a large load is applied to such a pneumatic tire 1 and the tread located in the center of the tread width direction W warps inward in the tire radial direction, the narrow groove 10 formed in the shoulder rib A2 and the shoulder rib A3 has a tire diameter. It inclines toward the tire equator line CL from the inner side to the outer side.

  That is, in the cross section of the tire along the tread width direction W and the tire radial direction D, the center line CL1 of the narrow groove 10 that inclines toward the tire equator line CL from the outer side in the tire radial direction toward the inner side is the pneumatic tire 1. Due to the applied load, it deforms to be orthogonal to the ground plane. For this reason, the pebbles caught in the narrow grooves 10 are easily discharged along with the rolling of the pneumatic tire 1.

  Therefore, according to the pneumatic tire 1 which concerns on such this embodiment, the tire which can further suppress generation | occurrence | production of a stone bite can be provided, suppressing generation | occurrence | production of uneven wear.

  In the present embodiment, the narrow groove 10 includes a sub-groove 12 that is formed wider in the tread width direction than the other narrow grooves 10. For this reason, among the ribs forming the narrow groove 10, the sub-groove 12 is formed in a particularly high-rigidity rib, thereby further suppressing the uneven rigidity of the rib. For this reason, the pneumatic tire 1 can further suppress the occurrence of uneven wear.

  Second Embodiment In the first embodiment described above, in the pneumatic tire 1, the sub-groove 12 is formed with a constant cross-sectional area along the tire radial direction D.

  In the second embodiment, a configuration in which the shape of the sub-groove 12 is different from that in the first embodiment will be described with reference to FIGS. FIG. 5 is a perspective view of a narrow groove according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view in the tire radial direction of the minor groove according to the second embodiment of the present invention. FIG. 7 is a tread surface view of the sub-groove according to the second embodiment of the present invention. In FIG. 7, in order to clarify the area S2 of the inner groove portion 30A, only the area S2 is hatched. In the present embodiment, (1) the structure of the sub-groove and (2) functions and effects will be described. In the second embodiment, only differences from the first embodiment are described, and descriptions of other configurations are omitted.

(1) Configuration of Sub-groove As shown in FIGS. 5 and 6, in the present embodiment, the narrow groove 10 </ b> A includes a sub-groove 12 </ b> A that is formed wider in the tread width direction than other narrow grooves 10 </ b> A. . The sub-groove 12A includes an outer groove 20A formed along the tire radial direction D from the surface of the tread 40, and an inner groove 30A that is continuous with the outer groove 20A and is located on the inner side in the tire radial direction than the outer groove 20A. The

  The outer groove portion 20A is formed by a first outer surface portion 22A that extends along the tire radial direction D and a second outer surface portion 22B that faces the first outer surface portion 22A and extends along the tire radial direction D.

  The inner groove portion 30A is formed by the first inner wall portion 31A, the second inner wall portion 31B, and the bottom portion 34. Specifically, the first inner wall portion 31A continues to the first outer surface portion 22A, protrudes to the inside of the inner groove portion 30A from the first outer surface portion 22A, and extends along the tire radial direction D. The second inner wall portion 31B faces the first inner wall portion 31A, continues to the second outer surface portion 22B, protrudes to the inner groove portion 30A from the second outer surface portion 22B, and extends along the tire radial direction D. . The first inner wall portion 31A and the second inner wall portion 31B are formed to be symmetric with respect to the center line CL3. The bottom 34 becomes the bottom of the inner groove 30A, is connected to the first inner wall 31A and the second inner wall 31B, and extends along the tire circumferential direction R.

  The first inner wall portion 31A and the second inner wall portion 31B are connected to the upper surface of the wall substantially parallel to the surface of the tread 40 and the upper surface of the wall, and the bottom 34 extends along the tire radial direction D and the tire circumferential direction R from the wall upper surface. And a side surface extending to each. Specifically, the first inner wall portion 31A includes a wall upper surface 36A and a side surface 32A. Similarly, the second inner wall portion 31B includes a wall upper surface 36B and a side surface 32B. The side surface 32A and the side surface 32B are formed along the center line CL3 and face each other. The wall upper surface 36A and the wall upper surface 36B are orthogonal to the center line CL3.

  The distance L1 along the tire radial direction D from the surface of the tread 40 to the tire radial direction outer ends of the first inner wall portion 31A and the second inner wall portion 31B is the tread width of the outer groove portion 20A on the surface of the tread 40. It is shorter than the width L2 along the direction and longer than the distance L3 from the side surface 32A of the first inner wall portion 31A to the side surface 32B of the second inner wall portion 31B.

  As shown in FIG. 7, in the tread surface view, the area S2 of the inner groove portion 30A is smaller than the area S1 of the outer groove portion 20A.

(2) Action / Effect In the sub-groove 12A according to the present embodiment, the area S2 of the inner groove 30A is smaller than the area S1 of the outer groove 20A in the tread surface view. For this reason, along with rolling of the pneumatic tire, etc., even if pebbles enter the sub-groove 12A, pebbles are less likely to enter the inner groove portion 30A located on the inner side in the tire radial direction than the outer groove portion 20A. Easily discharged from the secondary groove 12A.

  Therefore, according to the pneumatic tire according to this embodiment, it is possible to provide a tire that can further suppress the occurrence of uneven wear while suppressing the occurrence of stone biting.

  According to the pneumatic tire according to the present embodiment, the inner groove portion 30A is formed by the first inner wall portion 31A, the second inner wall portion 31B, and the bottom portion 34. That is, since the first inner wall portion 31A and the second inner wall portion 31B repel the pebbles outward in the tire radial direction, the pebbles are less likely to enter the sub-groove 12A, and the occurrence of stone biting can be suppressed.

  Further, the inner groove portion 30A repels the pebbles outward in the tire radial direction at two points by the pair of first inner wall portion 31A and second inner wall portion 31B facing each other, so the first inner wall portion 31A and the second inner wall portion The portion 31B is less likely to be pushed inward in the tire radial direction by pebbles. Therefore, pebbles are more difficult to enter the sub-groove 12A, and the occurrence of stone biting can be further suppressed.

  According to the pneumatic tire according to the present embodiment, the first inner wall portion 31A and the second inner wall portion 31B include a wall upper surface (wall upper surface 36A and wall upper surface 36B) substantially parallel to the surface of the tread 40, and a wall upper surface. And side surfaces (side surface 32A, side surface 32B) extending from the upper surface of the wall to the bottom portion 34 along the tire radial direction D and the tire circumferential direction R, respectively. For this reason, even when the wall upper surface 36A and the wall upper surface 36B are applied with a force directed inward in the tire radial direction by pebbles that are going to enter the inner groove 30A, the inner groove 30A is aligned along the tire radial direction. Since the side surface 32A (or side surface 32B) is formed, the pebbles can be rebounded outward in the tire radial direction without being deformed inward in the tire radial direction. Therefore, pebbles are more difficult to enter the sub-groove 12A, and the occurrence of stone biting can be further suppressed.

  According to the pneumatic tire according to the present embodiment, the wall upper surface 36A and the wall upper surface 36B are substantially parallel to the surface of the tread 40. Therefore, the first inner wall portion 31A and the second inner wall portion 31B have the sub-groove 12A. It becomes harder to be pushed into the pebbles that enter.

  In the present embodiment, the distance L1 along the tire radial direction D from the surface of the tread 40 to the outer ends in the tire radial direction of the first inner wall portion 31A and the second inner wall portion 31B is the outer side on the surface of the tread 40. Since the groove portion 20A is shorter than the width L2 along the tread width direction, the outer groove portion 20A is less likely to bite pebbles.

  In the present embodiment, the distance L1 is longer than the distance L3 from the side surface 32A of the first inner wall portion 31A to the side surface 32B of the second inner wall portion 31B. For this reason, even if the pebbles are pushed into the outer groove 20A as the tire rolls, the pebbles are more difficult to enter the inner groove 30A.

  [Comparative Evaluation] Next, in order to further clarify the effects of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (1) an evaluation method and (2) an evaluation result will be described. Note that the present invention is not limited to these examples.

(1) Evaluation method Using the pneumatic tires of Examples 1 and 2, (1.1) stone biting was evaluated. The pneumatic tires according to comparative examples and examples used for comparative evaluation will be specifically described. In addition, the data regarding a pneumatic tire were measured on the conditions shown below.

・ Tire size: 175 / 80R14 88S
・ Rim size: Standard rim described in ETRTO ・ Internal pressure condition: Standard internal pressure described in ETRTO ・ Load condition: Maximum load described in ETRTO (maximum load capacity)
-Test vehicle type: Domestic car sedan-Number of sub-grooves per pneumatic tire: 148 Configurations other than the narrow grooves and sub-grooves provided in each pneumatic tire are the same.

  The pneumatic tire according to Example 1 has the same configuration as the pneumatic tire 1 according to the first embodiment. Specifically, in the pneumatic tire according to the first embodiment, a narrow groove and a secondary groove are formed.

  The pneumatic tire according to Example 2 has the same configuration as the pneumatic tire according to the second embodiment. Specifically, the secondary groove of the pneumatic tire according to the second embodiment includes an outer groove portion and an inner groove portion.

(1.1) Evaluation of stone bite Evaluation method: Each pneumatic tire was mounted on a vehicle, traveled on a rough road containing pebbles for about 9000 km, and the number of stone bites per pneumatic tire was measured.

(2) Evaluation result The evaluation result using the pneumatic tire which concerns on the comparative example and Example mentioned above is demonstrated referring Table 1. FIG.

  Compared with the pneumatic tire according to Example 1, the pneumatic tire according to Example 2 was able to suppress the occurrence of stone biting.

[Other Embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. In the second embodiment of the present invention described above, the inner groove portion 30A is formed by the pair of first inner wall portion 31A and second inner wall portion 31B and the bottom portion 34, but is not limited thereto. For example, as shown in FIG. 8, the sub-groove 12B includes an outer groove portion 20B and an inner groove portion 30B. The inner groove portion 30B may be formed by a side surface portion 22C, an inner wall portion 31C, and a bottom portion 34B that are continuous from the first outer surface portion of the outer groove portion 20B in the tire radial direction.

  In the second embodiment of the present invention described above, the inner groove portion 30A is formed with the wall upper surface 36A orthogonal to the center line CL3 of the narrow groove, but the wall upper surface 36A needs to be parallel to the tread surface. No, it may be inclined inward in the tire radial direction.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

θ1 ... Inclination angle, A1 ... Center rib, A2, A3 ... Shoulder rib, CL ... Tire equator line, D ... Tire radial direction, L1 ... Distance, L2 ... Width, L3 ... Distance, R ... Tire circumferential direction, S1, S2 ... area, W ... tread width direction, W1 ... groove width, W2 ... groove width, 1 ... pneumatic tire, CL1, 2, 3 ... center line, 10, 10A ... narrow groove, 12, 12A, 12B ... minor groove, 20, 20A, 20B ... outer groove, 22 ... groove, 22A ... first outer surface, 22B ... second outer surface, 22C ... side surface, 30A ... inner groove, 30B ... inner groove, 31A ... first inner wall, 31B: Second inner wall portion, 31C: Inner wall portion, 32A, 32B ... Side surface, 34, 34B ... Bottom portion, 36A, 36B ... Wall upper surface, 40 ... Tread, 50 ... Hole portion, 110, 112, 114 ... Circumferential direction Groove, 120, 122 ... Horizontal groove

Claims (2)

A tire Ru comprising a plurality of ribs extending along the tire circumferential direction,
The plurality of ribs include shoulder ribs located at shoulder portions on the outer side in the tread width direction,
The shoulder rib is formed with a narrow groove extending along the tire circumferential direction ,
In the tread width direction and a cross section along the tire radial direction, the center line of the narrow groove in the tread width direction is inclined to the tire equator line side from the outer side in the tire radial direction towards the inside,
The narrow groove includes a secondary groove having a predetermined width in the tread width direction, and another narrow groove that is continuous with the secondary groove in the tire circumferential direction and whose width in the tread width direction is narrower than the secondary groove,
The secondary groove includes an outer groove formed along the tire radial direction from the surface of the tread, an inner groove that is continuous with the outer groove in the tire radial direction, and is located on the inner side of the outer groove in the tire radial direction. Consisting of
In the tread surface view, the area of the inner groove portion is smaller than the area of the outer groove portion,
The outer groove portion is formed by a first outer surface portion extending along the tire radial direction and a second outer surface portion facing the first outer surface portion and extending along the tire radial direction,
The inner groove portion is connected to the first outer surface portion, protrudes to the inner side of the inner groove portion from the first outer surface portion, and extends along the tire radial direction, and the second outer surface portion. Continuing from the second outer surface portion to the inside of the inner groove portion, the second inner wall portion extending along the tire radial direction, the first inner wall portion and the second inner wall portion, and Formed by the bottom extending along the tire circumferential direction as the bottom of the inner groove,
Each of the first inner wall portion and the second inner wall portion has a wall upper surface substantially parallel to the surface of the tread and a side surface extending from the wall upper surface to the bottom along the tire radial direction . The distance along the tire radial direction to the end in the tire radial direction outer side of the first inner wall portion from the surface and the second inner wall portion of the tread, the tread width of the outer groove on the surface of the tread shorter than the width along the direction, and the tire according to a long claim 1 than the distance from the side surface of said first inner wall portion to the side surface of the second inner wall portion.