tire

Abstract

To provide a tire capable of achieving both NV performance and wet performance.SOLUTION: Among a plurality of circumferential grooves 30, an inner shoulder circumferential groove 31, which is the innermost circumferential groove 30 in a vehicle attachment direction, and an inner center circumferential groove 32, which is a circumferential groove 30 adjacent to the inner shoulder circumferential groove 31, are located on an inner side in the vehicle attachment direction to a tire equatorial plane Cl. In the inner shoulder circumferential groove 31, a groove wall angle A of a groove wall 31a located closer to an inner side in the vehicle attachment direction and a groove wall angle B of the groove wall 31a located closer to an outer side in the vehicle attachment direction, satisfy a relation of A>B, and the groove wall angle A and the groove wall angle B are within a range of 13° to 20° and within a range of 8° to 12°, respectively. In the inner center circumferential groove 32, a groove wall angle C of a groove wall 32a located closer to the inner side in the vehicle attachment direction and a groove wall angle D of the groove wall 32a located closer to the outer side in the vehicle attachment direction are both within a range of 8° to 12°.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Tires mounted on vehicles are required to have various performance characteristics, and some conventional tires have grooves on the tread surface that have been designed to meet the desired performance characteristics. For example, the tire described in Patent Document 1 suppresses uneven wear and the occurrence of groove cracks by defining the groove wall angle and the curvature radius of the bottom of the groove wall.

[0003] In addition, in the pneumatic radial tire described in Patent Document 2, the cornering force is greatly increased by providing an expanded inclined portion on the groove wall of the circumferential groove in the tread side region located on the outer side of the vehicle when the tire is mounted on the vehicle. In addition, in the pneumatic radial tire described in Patent Document 3, one circumferential main groove is provided in one half of the tread surface with the tire equator as the boundary, and two circumferential main grooves are provided in the other half, and the angles of the groove walls of the three circumferential groove portions are specified, thereby achieving both hydroplaning properties and quietness during cornering. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5436439 [Patent Document 2] Patent No. 2977879 [Patent Document 3] JP 2013-189126 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, the grooves formed on the tread surface of a tire are intended to improve wet performance, which is the driving performance on wet roads, but the grooves formed on the tread surface also affect NV (Noise Vibration) performance, which is the performance regarding noise generated from the tire when the vehicle is running. Reducing the groove width and groove volume of the grooves formed on the tread surface is effective for improving NV performance, but reducing the groove width and groove volume of the grooves makes it difficult to ensure drainage, and therefore wet performance is likely to deteriorate. For this reason, it is very difficult to achieve both NV performance and wet performance.

[0006] The present invention has been made in view of the above, and has an object to provide a tire that can achieve both NV performance and wet performance. [Means for solving the problem]

[0007] In order to solve the above-described problems and achieve the object, the tire according to the present invention includes a plurality of circumferential grooves extending in the tire circumferential direction. Among the plurality of circumferential grooves, the innermost circumferential groove in the vehicle mounting direction is defined as the inner shoulder circumferential groove, and when the circumferential groove adjacent to the inner shoulder circumferential groove in the tire width direction is defined as the inner center circumferential groove, the inner shoulder circumferential groove is located on the inner side in the vehicle mounting direction with respect to the tire equatorial plane, and the inner center circumferential groove is located on the inner side in the vehicle mounting direction with respect to the tire equatorial plane or on the tire equatorial plane. The inner shoulder circumferential groove satisfies the relationship A > B between the groove wall angle A with respect to the tire radial direction of the groove wall located closer to the inner side in the vehicle mounting direction among a pair of groove walls facing each other in the tire width direction and the groove wall angle B with respect to the tire radial direction of the groove wall located closer to the outer side in the vehicle mounting direction, and the groove wall angle A is in the range of 13° or more and 20° or less, and the groove wall angle B is in the range of 8° or more and 12° or less. The inner center circumferential groove is characterized in that both the groove wall angle C with respect to the tire radial direction of the groove wall located closer to the inner side in the vehicle mounting direction among a pair of groove walls facing each other in the tire width direction and the groove wall angle D with respect to the tire radial direction of the groove wall located closer to the outer side in the vehicle mounting direction are in the range of 8° or more and 12° or less.

[0008] Further, in the above tire, it is preferable that the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy the relationship -1° ≤ B - C ≤ 1°.

[0009] Further, in the above tire, it is preferable that the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy the relationship B < C.

[0010] Further, in the above tire, it is preferable that the inner center circumferential groove satisfies the relationship -2° ≤ D - C ≤ 2° between the groove wall angle C and the groove wall angle D.

[0011] Further, in the above tire, it is preferable that the groove width W1 of the inner shoulder circumferential groove and the groove width W2 of the inner center circumferential groove satisfy the relationship of W2 < W1.

[0012] Further, in the above tire, it is preferable that the groove width W1 of the inner shoulder circumferential groove and the groove width W2 of the inner center circumferential groove satisfy the relationship of 1.0 ≦ W1 / W2 ≦ 1.2.

[0013] Further, in the above tire, a plurality of land portions partitioned by the circumferential grooves are provided. Among the plurality of land portions, an inner shoulder land portion, which is the land portion partitioned by the inner shoulder circumferential groove on the inner side in the tire width direction, and an inner intermediate land portion, which is the land portion partitioned by the inner shoulder circumferential groove and the inner center circumferential groove on both sides in the tire width direction, preferably have sipes disposed thereon.

[0014] Further, in the above tire, the sipes disposed on the inner intermediate land portion communicate with both the inner shoulder circumferential groove and the inner center circumferential groove, and include sipes that communicate with the inner shoulder circumferential groove via notches and sipes that communicate with the inner center circumferential groove via notches. The sipes disposed on the inner shoulder land portion extend in the tire width direction across the ground contact end and communicate with the inner shoulder circumferential groove, and at least some of the plurality of sipes disposed on the inner shoulder land portion communicate with the inner shoulder circumferential groove via notches. Among the plurality of land portions, on the center land portion, which is the land portion partitioned by the inner center circumferential groove and is located on the opposite side of the inner intermediate land portion in the tire width direction with respect to the inner center circumferential groove, it is preferable that sipes that communicate with the inner center circumferential groove via notches are disposed.

[0015] Furthermore, in the above tire, it is preferable that the cutout portion disposed in the inner shoulder land portion and communicating with the inner shoulder circumferential groove has a maximum length Dc1 in the tire width direction within a range of 0.10≦Dc1 / Wb1≦0.15 with respect to the ground contact width Wb1 of the inner shoulder land portion, the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove has a maximum length Dc2 in the tire width direction within a range of 0.35≦Dc2 / Wb2≦0.45 with respect to the ground contact width Wb2 of the inner intermediate land portion, and the relationship between the maximum length Dc2 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and the maximum length Dc3 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 1.1≦Dc2 / Dc3≦1.5.

[0016] Furthermore, in the above tire, it is preferable that the cutout portion disposed in the inner shoulder land portion and communicating with the inner shoulder circumferential groove has a maximum depth h1 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.45≦h1 / Hs≦0.55, and the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove has a maximum depth h2 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.55≦h2 / Hs≦0.65, and a relationship between the maximum depth h2 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and the maximum depth h3 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 0.99≦h2 / h3≦1.01.

[0017] In addition, in the above tire, it is preferable that the width in the tire circumferential direction of the cutout portion to which the sipe communicates is within a range of 7 to 13 times the width in the tire circumferential direction of the sipe to which the cutout portion communicates.

[0018] In addition, in the tire, it is preferable that the cutouts arranged in the inner intermediate land portion are arranged such that the cutouts communicating with the inner shoulder circumferential groove and the cutouts communicating with the inner center circumferential groove are alternately arranged in the tire circumferential direction.

[0019] In the tire, it is preferable that the sipe disposed in the inner shoulder land portion has a three-dimensional shape.

[0020] In the tire, the tread portion preferably has a cap tread having a tan δ at 0° C. in the range of 0.88 to 0.94 and a rubber hardness in the range of 58 to 63.

[0021] In addition, in the above tire, it is preferable that four circumferential grooves are arranged, the tread pattern of the tread portion is an asymmetric pattern that is asymmetric on both sides of the tire equatorial plane in the tire width direction, and that among the multiple land portions, the outer shoulder land portion, which is the land portion located outermost in the vehicle mounting direction, has a plurality of sipes arranged in the tire circumferential direction without having lug grooves and extending in the tire width direction.

[0022] In the tire, it is preferable that the four circumferential grooves have a groove width that narrows from the inner side toward the outer side in the vehicle mounting direction. Effect of the Invention

[0023] The tire according to the present invention has an effect of achieving both NV performance and wet performance. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic tire according to an embodiment. [Diagram 2] FIG. 2 is a view taken along the line EE of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line FF of FIG. [Figure 4] FIG. 4 is a detailed view of a portion of the tread portion shown in FIG. 2 that is located on the inner side of the tire equatorial plane in the vehicle mounting direction. [Diagram 5] FIG. 5 is a cross-sectional view taken along line FF in FIG. 2, and is an explanatory view of a cutout portion communicating with a circumferential groove. [Figure 6A] FIG. 6A is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 6B] FIG. 6B is a chart showing the results of a performance evaluation test of a pneumatic tire. [Figure 6C] FIG. 6C is a chart showing the results of a performance evaluation test of a pneumatic tire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of a tire according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

[0026] [Embodiment] In the following description, a pneumatic tire 1 will be used as an example of a tire according to the present invention. The pneumatic tire 1, which is an example of a tire, can be filled with air, an inert gas such as nitrogen, and other gases.

[0027] In the following description, the tire radial direction refers to a direction perpendicular to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1, the tire radial inner side refers to the side facing the tire rotation axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotation axis as the central axis. The tire width direction refers to a direction parallel to the tire rotation axis, the tire width inner side refers to the side facing the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane perpendicular to the tire rotation axis and passing through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides with a tire width centerline which is the center position of the pneumatic tire 1 in the tire width direction. The tire width is the width in the tire width direction between the portions located outermost in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line refers to a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridian section refers to a section obtained by cutting the tire with a plane that includes the tire rotation axis.

[0028] FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 according to this embodiment has a specified mounting direction relative to a vehicle, that is, a direction when mounted on a vehicle. That is, in the pneumatic tire 1 shown in this embodiment, the side facing the inside of the vehicle when mounted on the vehicle is the inside of the vehicle mounting direction, and the side facing the outside of the vehicle when mounted on the vehicle is the outside of the vehicle mounting direction. Note that the designation of the inside of the vehicle mounting direction and the outside of the vehicle mounting direction is not limited to when mounted on a vehicle. For example, when assembled on a rim, the orientation of the rim relative to the inside and outside of the vehicle in the tire width direction is determined, so that when assembled on a rim, the orientation of the pneumatic tire 1 relative to the inside and outside of the vehicle mounting direction in the tire width direction is specified. In addition, the pneumatic tire 1 has a mounting direction display portion (not shown) that indicates the mounting direction relative to the vehicle. The mounting direction display portion is formed, for example, by a mark or unevenness attached to the sidewall portion 8 of the tire. For example, ECER30 (Article 30 of the European Economic Commission Regulation) requires that a mounting direction indication portion be provided on the sidewall portion 8 that is on the outer side in the vehicle mounting direction when the tire is mounted on the vehicle. The pneumatic tire 1 according to the present embodiment is a pneumatic tire 1 that is mainly used for passenger cars.

[0029] In the pneumatic tire 1 according to this embodiment, a tread portion 2 is disposed on the outermost portion in the tire radial direction when viewed in a tire meridian section, and the tread portion 2 has a cap tread 4 made of a rubber composition. The surface of the tread portion 2, i.e., the portion that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 is traveling, is formed as a tread contact surface 3, and the tread contact surface 3 constitutes a part of the contour of the pneumatic tire 1.

[0030] The cap tread 4 of the tread portion 2 uses a compound having a tan δ of 0.88 to 0.94 at 0°C and a rubber hardness of 58 to 63. The tan δ at 0°C is measured in accordance with JIS K6394 using a viscoelasticity spectrometer (e.g., manufactured by Toyo Seiki Seisakusho) under conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 0°C. The rubber hardness is the JIS-A hardness, which is a durometer hardness measured in accordance with JIS K6253 using an A-type durometer at a temperature of 20°C.

[0031] Shoulder portions 5 are located at both outer ends of the tread portion 2 in the tire width direction, and sidewall portions 8 are arranged on the tire radially inner sides of the shoulder portions 5. That is, the sidewall portions 8 are arranged on both sides in the tire width direction of the tread portion 2. In other words, the sidewall portions 8 are arranged at two locations on both sides of the pneumatic tire 1 in the tire width direction, and form the outermost exposed portions of the pneumatic tire 1 in the tire width direction.

[0032] A bead portion 10 is located on the tire radially inner side of each sidewall portion 8 located on both sides in the tire width direction. The bead portions 10 are located at two positions on both sides of the tire equatorial plane CL, similar to the sidewall portions 8, i.e., a pair of the bead portions 10 are located on both sides of the tire equatorial plane CL in the tire width direction. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on the tire radially outer side of the bead core 11. The bead core 11 is an annular member formed into a circular ring shape by bundling bead wires, which are steel wires, and the bead filler 12 is a rubber member located on the tire radially outer side of the bead core 11.

[0033] Further, the belt layer 14 is disposed in the tread portion 2. The belt layer 14 is configured by a multi-layer structure in which a plurality of belts 141, 142 and a belt cover 143 are laminated, and in this embodiment, two layers of belts 141, 142 are laminated. The belts 141, 142 constituting the belt layer 14 are configured by covering a plurality of belt cords made of steel or organic fiber materials such as polyester, rayon, and nylon with a coating rubber and rolling them, and the belt angle, which is defined as the inclination angle of the belt cords with respect to the tire circumferential direction, is within a predetermined range (for example, 20° or more and 55° or less). The two layers of belts 141, 142 have different belt angles. For this reason, the belt layer 14 is configured as a so-called cross-ply structure in which the two layers of belts 141, 142 are laminated with the inclination directions of the belt cords crossing each other. In other words, the two layers of belts 141, 142 are provided as so-called cross belts in which the belt cords of the respective belts 141, 142 are arranged in a direction in which they cross each other.

[0034] The belt cover 143 is formed by covering a plurality of belt cover cords made of steel or organic fiber material such as polyester, rayon, or nylon with coating rubber and rolling the covered cords, and the belt angle, defined as the inclination angle of the belt cover cords with respect to the tire circumferential direction, is within a predetermined range (for example, 0° to 10°). The belt cover 143 is, for example, a strip material made of one or more belt cover cords covered with coating rubber, and is formed by winding the strip material in a spiral shape around the tire rotation axis from the outer side in the tire radial direction of the two-layered belts 141 and 142.

[0035] A carcass layer 13 containing the cords of the radial ply is provided continuously on the inner side in the tire radial direction of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 8. Therefore, the pneumatic tire 1 according to this embodiment is configured as a so-called radial tire. The carcass layer 13 has a single-layer structure consisting of one carcass ply, or a multi-layer structure consisting of a plurality of carcass plies stacked together, and is toroidally spanned between a pair of bead portions 10 arranged on both sides in the tire width direction to form the framework of the tire.

[0036] Specifically, the carcass layer 13 is disposed from one bead portion 10 to the other bead portion 10 of a pair of bead portions 10 located on both sides in the tire width direction, and is wound around the bead core 11 at the bead portion 10 toward the outside in the tire width direction so as to envelop the bead core 11 and the bead filler 12. The bead filler 12 is a rubber material disposed in a space formed on the outside in the tire radial direction of the bead core 11 by folding back the carcass layer 13 at the bead portion 10 in this manner. The belt layer 14 is disposed on the outside in the tire radial direction of the portion of the carcass layer 13 that is stretched between the pair of bead portions 10 and that is located in the tread portion 2. The carcass ply of the carcass layer 13 is formed by covering a plurality of carcass cords made of steel or organic fiber material such as aramid, nylon, polyester, or rayon with a coating rubber and rolling the covered cords. The carcass cords constituting the carcass ply are arranged in parallel at a certain angle to the tire circumferential direction while being aligned along the tire meridian direction.

[0037] A rim cushion rubber 17 that constitutes the contact surface of the bead portion 10 with the rim flange is disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the bead core 11 and the turned-up portion of the carcass layer 13 in the bead portion 10. An inner liner 16 is formed along the carcass layer 13 on the inner side of the carcass layer 13 or on the inner side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 forms a tire inner surface 18 that is the inner surface of the pneumatic tire 1.

[0038] FIG. 2 is a view taken along the arrow EE in FIG. 1. In the tread portion 2, a plurality of circumferential grooves 30 extending in the tire circumferential direction are formed in the tread contact surface 3, and a plurality of land portions 20 are partitioned on the surface of the tread portion 2 by the plurality of circumferential grooves 30. In this embodiment, four circumferential grooves 30 are formed side by side in the tire width direction. The four circumferential grooves 30 are arranged two on each side of the tire equatorial plane CL in the tire width direction. These circumferential grooves 30 are grooves that are obligated to display a wear indicator as stipulated by JATMA. The circumferential grooves 30 have a groove width in the range of 8.0 mm to 15.0 mm, and a groove depth in the range of 6.9 mm to 9.0 mm.

[0039] In this embodiment, the so-called tread pattern of the tread portion 2, which is a pattern of the shape and arrangement of the circumferential grooves 30 formed in the tread portion 2, is an asymmetric pattern on both sides in the tire width direction with the tire equatorial plane CL as the boundary. That is, the tread pattern of the tread portion 2 is not line symmetric with the tire equatorial plane CL as the axis of symmetry, but is an asymmetric pattern that is asymmetric on both sides of the tire equatorial plane CL in the tire width direction. In this embodiment, in which the tread pattern is an asymmetric pattern, the groove width of the four circumferential grooves 30 narrows from the inner side to the outer side in the vehicle mounting direction. In this case, the groove width is the groove width at the position of the opening of the circumferential groove 30 relative to the tread contact surface 3.

[0040] The four circumferential grooves 30 are, from the inner side in the vehicle mounting direction to the outer side in the vehicle width direction, an inner shoulder circumferential groove 31, an inner center circumferential groove 32, an outer center circumferential groove 33, and an outer shoulder circumferential groove 34. Of the four circumferential grooves 30, the inner shoulder circumferential groove 31 and the inner center circumferential groove 32 are disposed on the inner side in the vehicle mounting direction with respect to the tire equatorial plane CL, and the outer center circumferential groove 33 and the outer shoulder circumferential groove 34 are disposed on the outer side in the vehicle mounting direction with respect to the tire equatorial plane CL.

[0041] Specifically, the inner shoulder circumferential groove 31 is the innermost circumferential groove 30 in the vehicle mounting direction, and the inner center circumferential groove 32 is the circumferential groove 30 adjacent to the inner shoulder circumferential groove 31 on the outer side in the vehicle mounting direction in the tire width direction. The outer shoulder circumferential groove 34 is the outermost circumferential groove 30 in the vehicle mounting direction, and the outer center circumferential groove 33 is the circumferential groove 30 adjacent to the outer shoulder circumferential groove 34 on the inner side in the vehicle mounting direction in the tire width direction.

[0042] The land portion 20 defined by the circumferential groove 30 includes an inner shoulder land portion 21, an inner intermediate land portion 22, a center land portion 23, an outer intermediate land portion 24, and an outer shoulder land portion 25. Of these, the inner shoulder land portion 21 is disposed outboard in the tire width direction relative to the inner shoulder circumferential groove 31, and its inner portion in the tire width direction constitutes the land portion 20 defined by the inner shoulder circumferential groove 31. In other words, the inner shoulder land portion 21 constitutes the land portion 20 disposed innermost in the vehicle mounting direction.

[0043] The inner intermediate land portion 22 is a land portion 20 defined on both sides in the tire width direction by the inner shoulder circumferential groove 31 and the inner center circumferential groove 32. That is, the inner intermediate land portion 22 is defined by the inner shoulder circumferential groove 31 at the outer portion in the tire width direction, and by the inner center circumferential groove 32 at the inner portion in the tire width direction.

[0044] The center land portion 23 is located on the opposite side to the side where the inner intermediate land portion 22 is located in the tire width direction with respect to the inner center circumferential groove 32, and is a land portion 20 defined by the inner center circumferential groove 32 and the outer center circumferential groove 33. That is, the center land portion 23 is a land portion 20 defined on both sides in the tire width direction by the inner center circumferential groove 32 and the outer center circumferential groove 33. In this way, the center land portion 23 defined on both sides in the tire width direction by the inner center circumferential groove 32 and the outer center circumferential groove 33 is disposed on the tire equatorial plane CL.

[0045] The outer intermediate land portion 24 is a land portion 20 defined on both sides in the tire width direction by the outer center circumferential groove 33 and the outer shoulder circumferential groove 34. That is, the outer intermediate land portion 24 is defined by the outer center circumferential groove 33 at the inner portion in the tire width direction, and by the outer shoulder circumferential groove 34 at the outer portion in the tire width direction.

[0046] The outer shoulder land portion 25 is disposed outboard in the tire width direction relative to the outer shoulder circumferential groove 34, and its inner portion in the tire width direction is the land portion 20 defined by the outer shoulder circumferential groove 34. In other words, the outer shoulder land portion 25 is the land portion 20 disposed outermost in the vehicle mounting direction.

[0047] Further, a circumferential narrow groove 40 extending in the tire circumferential direction is disposed in the outer shoulder land portion 25. The circumferential narrow groove 40 is disposed outward in the tire width direction from the outer shoulder circumferential groove 34, and the groove width is narrower than the groove width of the circumferential narrow groove 40. In this embodiment, the circumferential narrow groove 40 has a groove width in the range of 1.5 mm to 2.0 mm, and a groove depth in the range of 3.5 mm to 4.5 mm.

[0048] The outer shoulder land portion 25 has the circumferential narrow grooves 40 arranged in this manner, so that the outer shoulder land portion 25 is divided in the tire width direction by the circumferential narrow grooves 40. That is, the outer shoulder land portion 25 has a first outer shoulder land portion 25a located on the inner side in the tire width direction relative to the circumferential narrow groove 40 and a second outer shoulder land portion 25b located on the outer side in the tire width direction relative to the circumferential narrow groove 40.

[0049] As described above, the sipes 50 and the cutouts 60 are arranged in each land portion 20 defined by the circumferential grooves 30. The sipes 50 arranged in the land portion 20 are formed to extend, for example, in the tire width direction. The ends of the sipes 50 may terminate within the land portion 20, or may open into another groove. The sipes 50 may extend in the tire width direction and be inclined toward the tire circumferential direction, or may extend in the tire width direction and bend toward the tire circumferential direction.

[0050] The sipes 50 referred to here are formed in the shape of narrow grooves on the tread contact surface 3, and when the pneumatic tire 1 is assembled to a specified rim and the internal pressure is set to a specified internal pressure, the wall surfaces constituting the narrow grooves do not come into contact with each other under no load, but when a load is applied vertically on a flat plate and the narrow groove is located in a part of the contact surface formed on the flat plate, or when the land portion 20 on which the narrow groove is formed collapses, the wall surfaces constituting the narrow grooves, or at least a part of the portion provided on the wall surface, come into contact with each other due to deformation of the land portion 20. In this embodiment, the sipes 50 have a groove width of 0.8 mm or less, and a maximum depth from the tread contact surface 3 within a range of 5.0 mm to 7.0 mm.

[0051] The specified rim here means the "standard rim" specified by JATMA, the "design rim" specified by TRA, or the "measuring rim" specified by ETRTO. The specified internal pressure means the "maximum air pressure" specified by JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO.

[0052] The sipe 50 may be a so-called three-dimensional sipe or a two-dimensional sipe. The three-dimensional sipe here refers to a sipe 50 having a curved wall surface with an amplitude in the width direction of the sipe 50 in both a cross-sectional view (a cross-sectional view including the width direction and depth direction of the sipe 50) in which the length direction of the sipe 50 is the normal direction, and a cross-sectional view (a cross-sectional view including the width direction and length direction of the sipe 50) in which the depth direction of the sipe 50 is the normal direction. The two-dimensional sipe refers to a sipe 50 having a straight wall surface in any cross-sectional view (a cross-sectional view including the width direction and depth direction of the sipe 50) in which the length direction of the sipe 50 is the normal direction.

[0053] The cutout portion 60 disposed in the land portion 20 is formed in a narrow groove shape that is relatively short in length and extends in the tire width direction, with one end communicating with the circumferential groove 30 and the other end terminating within the land portion 20. The cutout portion 60 that is short in length and extends in the tire width direction may be inclined toward the tire circumferential direction while extending in the tire width direction.

[0054] The sipes 50 arranged in the land portion 20 include an inner shoulder sipe 51, an inner intermediate sipe 52, a center sipe 53, an outer intermediate sipe 54, and an outer shoulder sipe 55. The cutout portions 60 arranged in the land portion 20 include an inner shoulder cutout portion 61, an inner intermediate cutout portion 62, a center cutout portion 63, an outer intermediate cutout portion 64, and an outer shoulder cutout portion 65.

[0055] Of these, the inner shoulder sipe 51 is a sipe 50 arranged in the inner shoulder land portion 21. The inner shoulder sipe 51 extends in the tire width direction straddling the ground contact edge T located on the inner shoulder land portion 21, and its end on the inner side in the tire width direction communicates with the inner shoulder circumferential groove 31 that defines the inner shoulder land portion 21. In the inner shoulder land portion 21, multiple inner shoulder sipes 51 extending in the tire width direction and straddling the ground contact edge T are arranged side by side in the tire circumferential direction.

[0056] In this case, the ground contact end T is the maximum width position in the tire width direction of the contact surface between the pneumatic tire 1 and a flat plate when the pneumatic tire 1 is mounted on a specified rim, a specified internal pressure is applied, and the tire is placed perpendicular to a flat plate in a stationary state and a load corresponding to a specified load is applied. The specified load here refers to the "maximum load capacity" specified by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO. However, in JATMA, in the case of passenger car tires, the specified internal pressure is an air pressure of 180 kPa, and the specified load is 88% of the maximum load capacity. In this embodiment, the ground contact end T is located on the inner shoulder land portion 21 and on the second outer shoulder land portion 25b of the outer shoulder land portion 25.

[0057] The inner shoulder cutout 61 is a cutout 60 disposed in the inner shoulder land portion 21. The inner shoulder cutout 61 has an inner end in the tire width direction that communicates with the inner shoulder circumferential groove 31 and extends a short length from the position of the inner shoulder circumferential groove 31 toward the outside in the tire width direction. The outer end of the inner shoulder cutout 61 in the tire width direction terminates within the inner shoulder land portion 21. In the inner shoulder land portion 21, a plurality of inner shoulder cutouts 61 are arranged side by side in the tire circumferential direction. At least some of the inner shoulder sipes 51 among the plurality of inner shoulder sipes 51 disposed in the inner shoulder land portion 21 communicate with the inner shoulder circumferential groove 31 via the inner shoulder cutout 61.

[0058] In this embodiment, the number of inner shoulder cutouts 61 is half the number of inner shoulder sipes 51. The inner shoulder sipes 51 communicate with every other inner shoulder cutout 61 in the tire circumferential direction. Therefore, the inner shoulder sipes 51 that communicate with the inner shoulder circumferential groove 31 via the inner shoulder cutout 61 and the inner shoulder sipes 51 that directly communicate with the inner shoulder circumferential groove 31 without via the inner shoulder cutout 61 are arranged alternately in the tire circumferential direction.

[0059] The inner shoulder sipe 51, which communicates with the inner shoulder circumferential groove 31 via the inner shoulder cutout 61, communicates with the end of the inner shoulder cutout 61 that terminates within the inner shoulder land portion 21, and thereby communicates with the inner shoulder circumferential groove 31 via the inner shoulder cutout 61.

[0060] The inner intermediate sipes 52 are sipes 50 arranged in the inner intermediate land portion 22. The inner intermediate sipes 52 extend in the tire width direction and are arranged between the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, and are connected to both the inner shoulder circumferential groove 31 and the inner center circumferential groove 32. In the inner intermediate land portion 22, a plurality of inner intermediate sipes 52 extending in the tire width direction are arranged side by side in the tire circumferential direction.

[0061] The inner intermediate cutout 62 is a cutout 60 disposed in the inner intermediate land portion 22. The inner intermediate cutout 62 has an inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 and an inner intermediate cutout 62 communicating with the inner center circumferential groove 32. The inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 has an outer end in the tire width direction communicating with the inner shoulder circumferential groove 31, extends a short length from the position of the inner shoulder circumferential groove 31 toward the inner side in the tire width direction, and ends inner in the tire width direction within the inner intermediate land portion 22. The inner intermediate cutout 62 communicating with the inner center circumferential groove 32 has an inner end in the tire width direction communicating with the inner center circumferential groove 32, extends a short length from the position of the inner center circumferential groove 32 toward the outer side in the tire width direction, and ends outer in the tire width direction within the inner intermediate land portion 22.

[0062] In the inner intermediate land portion 22, inner intermediate cutouts 62 communicating with the inner shoulder circumferential groove 31 and inner intermediate cutouts 62 communicating with the inner center circumferential groove 32 are arranged alternately in the tire circumferential direction. In other words, the inner intermediate cutouts 62 communicating with the inner shoulder circumferential groove 31 and the inner intermediate cutouts 62 communicating with the inner center circumferential groove 32 are arranged in a staggered manner in the tire circumferential direction.

[0063] In this embodiment, the same number of inner intermediate sipes 52 and inner intermediate cutouts 62 are arranged in the inner intermediate land portion 22. The inner intermediate sipes 52 are arranged alternately in the tire circumferential direction, with the inner intermediate sipes 52 communicating with the inner intermediate cutout 62 on the side communicating with the inner shoulder circumferential groove 31 and the inner intermediate sipes 52 communicating with the inner intermediate cutout 62 on the side communicating with the inner center circumferential groove 32.

[0064] The inner intermediate sipe 52 communicating with the inner intermediate cutout 62 on the side communicating with the inner shoulder circumferential groove 31 has an outer end in the tire width direction communicating with an end of the inner intermediate cutout 62 on the side terminating within the inner intermediate land portion 22, and communicates with the inner shoulder circumferential groove 31 via the inner intermediate cutout 62. Also, the inner end in the tire width direction of the inner intermediate sipe 52 communicating with the inner intermediate cutout 62 on the side communicating with the inner shoulder circumferential groove 31 directly communicates with the inner center circumferential groove 32.

[0065] The inner intermediate sipe 52 communicating with the inner intermediate cut-out 62 on the side communicating with the inner center circumferential groove 32 has an inner end in the tire width direction communicating with an end of the inner intermediate cut-out 62 on the side terminating within the inner intermediate land portion 22, and communicates with the inner center circumferential groove 32 via the inner intermediate cut-out 62. Also, the outer end in the tire width direction of the inner intermediate sipe 52 communicating with the inner intermediate cut-out 62 on the side communicating with the inner center circumferential groove 32 directly communicates with the inner shoulder circumferential groove 31.

[0066] The center sipes 53 are sipes 50 arranged in the center land portion 23, and the center cutouts 63 are cutouts 60 arranged in the center land portion 23. In this embodiment, the same number of center sipes 53 and center cutouts 63 are arranged in the center land portion 23. In detail, the center cutouts 63 have their inner ends in the vehicle mounting direction connected to the inner center circumferential groove 32 and extend a short length from the position of the inner center circumferential groove 32 toward the outer side in the vehicle mounting direction, and their outer ends in the vehicle mounting direction terminate within the center land portion 23.

[0067] The center sipe 53 has an end on the inside in the vehicle mounting direction that communicates with the end of the center cutout 63 that terminates within the center land portion 23, and extends from the end that communicates with the center cutout 63 toward the outside in the vehicle mounting direction. Therefore, the center sipe 53 communicates with the inner center circumferential groove 32 via the center cutout 63. The end of the center sipe 53 opposite to the end that communicates with the center cutout 63, i.e., the outside end of the center sipe 53 in the vehicle mounting direction, terminates within the center land portion 23. In the center land portion 23, a plurality of center sipes 53 and a plurality of center cutouts 63 that extend in the tire width direction and communicate with each other are arranged side by side in the tire circumferential direction.

[0068] The outer intermediate sipes 54 are sipes 50 arranged in the outer intermediate land portion 24, and the outer intermediate cutouts 64 are cutouts 60 arranged in the outer intermediate land portion 24. In this embodiment, the same number of outer intermediate sipes 54 and outer intermediate cutouts 64 are arranged in the outer intermediate land portion 24. In detail, the outer intermediate cutouts 64 have their inner ends in the vehicle mounting direction connected to the outer center circumferential groove 33 and extend a short length from the position of the outer center circumferential groove 33 toward the outside in the vehicle mounting direction, and their outer ends in the vehicle mounting direction terminate within the outer intermediate land portion 24.

[0069] The outer intermediate sipe 54 has an end on the inner side in the vehicle mounting direction that communicates with the end of the outer intermediate cutout 64 that terminates in the outer intermediate land portion 24, and extends from the end that communicates with the outer intermediate cutout 64 toward the outer side in the vehicle mounting direction. Therefore, the outer intermediate sipe 54 communicates with the outer center circumferential groove 33 via the outer intermediate cutout 64. The end of the outer intermediate sipe 54 opposite to the end that communicates with the outer intermediate cutout 64, i.e., the outer end of the outer intermediate sipe 54 in the vehicle mounting direction, terminates in the outer intermediate land portion 24. In the outer intermediate land portion 24, a plurality of outer intermediate sipes 54 and a plurality of outer intermediate cutouts 64 that extend in the tire width direction and communicate with each other are arranged side by side in the tire circumferential direction.

[0070] The outer shoulder sipes 55 are sipes 50 arranged in the outer shoulder land portion 25, and the outer shoulder cutouts 65 are cutouts 60 arranged in the outer shoulder land portion 25. In more detail, the outer shoulder sipes 55 are arranged in the second outer shoulder land portion 25b in the outer shoulder land portion 25, and the outer shoulder cutouts 65 are arranged in the first outer shoulder land portion 25a in the outer shoulder land portion 25.

[0071] The outer shoulder cutout 65 arranged in the first outer shoulder land portion 25a has an end portion on the inner side in the vehicle mounting direction that communicates with the outer shoulder circumferential groove 34. The outer shoulder cutout 65 that communicates with the outer shoulder circumferential groove 34 extends a short length from the position of the outer shoulder circumferential groove 34 toward the outside in the vehicle mounting direction, and the end portion on the outer side in the vehicle mounting direction terminates within the first outer shoulder land portion 25a. The first outer shoulder land portion 25a has a plurality of outer shoulder cutouts 65 arranged side by side in the tire circumferential direction, one end of which communicates with the outer shoulder circumferential groove 34 and the other end of which terminates within the first outer shoulder land portion 25a.

[0072] The outer shoulder sipes 55 arranged in the second outer shoulder land portion 25b extend in the tire width direction straddling the ground contact edge T located on the second outer shoulder land portion 25b, and their inner ends in the tire width direction communicate with the circumferential narrow grooves 40 formed in the outer shoulder land portion 25. In the second outer shoulder land portion 25b, multiple outer shoulder sipes 55 extending in the tire width direction and straddling the ground contact edge T are arranged side by side in the tire circumferential direction.

[0073] Of the sipes 50 and cutouts 60 thus formed, the inner intermediate sipe 52, the center sipe 53, the outer intermediate sipe 54, the inner intermediate cutout 62, the center cutout 63, the outer intermediate cutout 64, and the outer shoulder cutout 65 extend in the tire width direction and are inclined toward the same tire circumferential direction with respect to the tire width direction. Also, of the cutouts 60 arranged in the land portion 20, the cutouts 60 connected to the sipes 50 have a width in the tire circumferential direction that is within a range of 7 to 13 times the width in the tire circumferential direction of the sipes 50 connected to the cutouts 60.

[0074] In this embodiment, each land portion 20 does not have a lug groove extending in the tire width direction, but is formed as a rib extending in the tire circumferential direction. That is, each land portion 20 does not have a lug groove, and a plurality of sipes 50 extending in the tire width direction are arranged side by side in the tire circumferential direction. In particular, the inner shoulder land portion 21, the inner intermediate land portion 22, and the second outer shoulder land portion 25b are sipe-based land portions 20 in which a plurality of sipes 50 extending across the entire contact width in the tire width direction of each land portion 20 are arranged side by side in the tire circumferential direction.

[0075] 3 is a cross-sectional view taken along the FF line of FIG. 2. FIG. 3 is a schematic cross-sectional view showing the inner shoulder notch 61 and the inner intermediate notch 62 communicating with the inner shoulder circumferential groove 31, and the inner intermediate notch 62 and the center notch 63 communicating with the inner center circumferential groove 32 in one cross-sectional view. The inner shoulder circumferential groove 31 and the inner center circumferential groove 32, which are circumferential grooves 30 arranged on the inner side in the vehicle mounting direction with respect to the tire equatorial plane CL, are formed with a predetermined relationship between the angles of the groove walls. That is, the inner shoulder circumferential groove 31 and the inner center circumferential groove 32 both have groove walls inclined in a direction in which the groove width is larger on the opening side relative to the tread ground contact surface 3 than on the groove bottom side of the circumferential groove 30, but the inner shoulder circumferential groove 31 and the inner center circumferential groove 32 are formed with a predetermined relationship between the inclination angles of the inclined groove walls.

[0076] Specifically, in the inner shoulder circumferential groove 31, among the pair of groove walls 31a facing each other in the tire width direction, the groove wall angle A of the groove wall 31a located closer to the inner side in the vehicle mounting direction with respect to the tire diameter direction, and the groove wall angle B of the groove wall 31a located closer to the outer side in the vehicle mounting direction with respect to the tire diameter direction satisfy the relationship A > B. Further, in the inner shoulder circumferential groove 31, the groove wall angle A of the groove wall 31a located closer to the inner side in the vehicle mounting direction is within the range of 13° or more and 20° or less, and the groove wall angle B of the groove wall 31a located closer to the outer side in the vehicle mounting direction is within the range of 8° or more and 12° or less.

[0077] In the inner center circumferential groove 32, among the pair of groove walls 32a facing each other in the tire width direction, both the groove wall angle C of the groove wall 32a located closer to the inner side in the vehicle mounting direction with respect to the tire diameter direction and the groove wall angle D of the groove wall 32a located closer to the outer side in the vehicle mounting direction with respect to the tire diameter direction are within the range of 8° or more and 12° or less. Further, in the inner center circumferential groove 32, the groove wall angle C of the groove wall 32a located closer to the inner side in the vehicle mounting direction and the groove wall angle D of the groove wall 32a located closer to the outer side in the vehicle mounting direction satisfy the relationship -2° ≤ D - C ≤ 2°.

[0078] In the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, the groove wall angle B of the groove wall 31a located closer to the outer side in the vehicle mounting direction in the inner shoulder circumferential groove 31 and the groove wall angle C of the groove wall 32a located closer to the inner side in the vehicle mounting direction in the inner center circumferential groove 32 satisfy the relationship -1° ≤ B - C ≤ 1°. Further, it is preferable that the groove wall angle B of the groove wall 31a located closer to the outer side in the vehicle mounting direction in the inner shoulder circumferential groove 31 and the groove wall angle C of the groove wall 32a located closer to the inner side in the vehicle mounting direction in the inner center circumferential groove 32 satisfy the relationship B < C.

[0079] Note that the groove wall angles of these circumferential grooves 30 are defined by the angles of the groove walls excluding chamfers when chamfers are provided at the opening portions of the circumferential grooves 30 with respect to the tread ground contact surface 3. That is, the circumferential grooves 30 may have chamfers of, for example, 1.0 mm or less at the opening portions with respect to the tread ground contact surface 3. Also in this embodiment, chamfers are provided at the opening portions of the circumferential grooves 30 with respect to the tread ground contact surface 3, and the groove wall angles A, B, C, and D are the groove wall angles of the groove walls other than the portions where the chamfers are formed.

[0080] FIG. 4 is a detailed view of a portion of the tread portion 2 shown in FIG. 2 that is located inside the tire equatorial plane CL in the vehicle mounting direction. In this embodiment, the four circumferential grooves 30 become narrower in groove width from the inner side to the outer side in the vehicle mounting direction. For this reason, the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 satisfy the relationship W2 < W1. Note that it is preferable that the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 satisfy the relationship 1.0 ≦ W1 / W2 ≦ 1.2.

[0081] Also, the notches 60 arranged in each land portion 20 are formed to have a predetermined length in the tire width direction. Specifically, the maximum length Dc1 of the inner shoulder notch 61 arranged in the inner shoulder land portion 21 in the tire width direction is within the range of 0.10 ≦ Dc1 / Wb1 ≦ 0.15 with respect to the ground contact width Wb1 of the inner shoulder land portion 21. The ground contact width Wb1 of the inner shoulder land portion 21 in this case is the distance in the tire width direction between the inner shoulder circumferential groove 31 that partitions the inner portion of the inner shoulder land portion 21 in the tire width direction and the ground contact end T located on the inner shoulder land portion 21.

[0082] Furthermore, of the inner intermediate cutouts 62 arranged in the inner intermediate land portion 22, the inner intermediate cutouts 62 communicating with the inner shoulder circumferential groove 31 have a maximum length Dc2 in the tire width direction within a range of 0.35≦Dc2 / Wb2≦0.45 relative to the ground contact width Wb2 of the inner intermediate land portion 22. In this case, the ground contact width Wb2 of the inner intermediate land portion 22 is the distance in the tire width direction between the inner center circumferential groove 32 that defines the inner part of the inner intermediate land portion 22 in the tire width direction and the inner shoulder circumferential groove 31 that defines the outer part of the inner intermediate land portion 22 in the tire width direction.

[0083] In addition, the relationship between the maximum length Dc2 in the tire width direction of the inner intermediate cutout 62 that communicates with the inner shoulder circumferential groove 31 and the maximum length Dc3 in the tire width direction of the inner intermediate cutout 62 that communicates with the inner center circumferential groove 32 of the inner intermediate cutout 62 that is arranged in the inner intermediate land portion 22 is within the range of 1.1≦Dc2 / Dc3≦1.5.

[0084] Among the land portions 20 in which the thus formed cutout portions 60 are arranged, the inner shoulder sipe 51, which is the sipe 50 arranged in the inner shoulder land portion 21, is a three-dimensional sipe having a three-dimensional shape. On the other hand, the inner intermediate sipe 52, which is the sipe 50 arranged in the inner intermediate land portion 22, is a two-dimensional sipe having a two-dimensional shape.

[0085] FIG. 5 is an FF cross-sectional view of FIG. 2, and is an explanatory diagram of a cutout portion 60 communicating with the circumferential groove 30. Like FIG. 3, FIG. 5 is a cross-sectional schematic view illustrating the inner shoulder cutout portion 61 and the inner intermediate cutout portion 62 communicating with the inner shoulder circumferential groove 31, and the inner intermediate cutout portion 62 and the center cutout portion 63 communicating with the inner center circumferential groove 32 in one cross-sectional view. The cutout portion 60 arranged in each land portion 20 is also formed to a predetermined depth in the tire radial direction. Specifically, the inner shoulder cutout portion 61 arranged in the inner shoulder land portion 21 has a maximum depth h1 in the tire radial direction that is within a range of 0.45≦h1 / Hs≦0.55 with respect to the maximum depth Hs of the inner shoulder circumferential groove 31 to which the inner shoulder cutout portion 61 communicates.

[0086] Furthermore, among the inner intermediate cutouts 62 arranged in the inner intermediate land portion 22, the inner intermediate cutouts 62 that communicate with the inner shoulder circumferential groove 31 have a maximum depth h2 in the tire radial direction, relative to the maximum depth Hs of the inner shoulder circumferential groove 31, within the range of 0.55≦h2 / Hs≦0.65.

[0087] In addition, the relationship between the maximum depth h2 in the tire radial direction of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 and the maximum depth h3 in the tire radial direction of the inner intermediate cutout 62 communicating with the inner center circumferential groove 32 of the inner intermediate cutout 62 arranged in the inner intermediate land portion 22 is within the range of 0.99≦h2 / h3≦1.01.

[0088] When mounting the pneumatic tire 1 according to the present embodiment on a vehicle, the pneumatic tire 1 is assembled to a rim wheel, and is mounted on the vehicle in an inflated state by filling the inside with air. At this time, the pneumatic tire 1 according to the present embodiment is mounted on the vehicle in the specified direction because the mounting direction relative to the vehicle is specified. That is, the pneumatic tire 1 is mounted on the vehicle in the direction specified by the mounting direction indicator attached to the sidewall portion 8. As a result, the pneumatic tire 1 is mounted on the vehicle in an orientation in which the side on which the inner shoulder circumferential groove 31, which connects the inner shoulder cutout 61 and the inner intermediate cutout 62, is located is located on the inner side in the vehicle mounting direction, and the side on which the circumferential narrow groove 40 is located is located on the outer side in the vehicle mounting direction.

[0089] When a vehicle equipped with a pneumatic tire 1 runs, the pneumatic tire 1 rotates with the lower part of the tread contact surface 3 of the tread portion 2 in contact with the road surface. When a vehicle equipped with a pneumatic tire 1 runs on a dry road surface, the vehicle runs by transmitting driving force and braking force to the road surface and generating turning force mainly due to friction between the tread contact surface 3 and the road surface.

[0090] Furthermore, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters grooves such as the circumferential grooves 30 and the sipes 50, and these grooves drain the water between the tread surface 3 and the road surface while traveling. This makes it easier for the tread surface 3 to come into contact with the road surface, and the friction between the tread surface 3 and the road surface enables the vehicle to travel.

[0091] On the other hand, grooves such as the circumferential groove 30 formed in the tread contact surface 3 can also be a cause of noise generation when the pneumatic tire 1 rotates. In other words, when the pneumatic tire 1 rotates, the tread portion 2 elastically deforms when it comes into contact with the road surface, and the grooves elastically deform together with the tread portion 2, causing the air in the grooves to vibrate and generating air column resonance. When the pneumatic tire 1 rotates, noise is generated due to air column resonance occurring in the grooves in this way.

[0092] In contrast, in this embodiment, the groove wall angle A of the groove wall 31a located inward in the vehicle mounting direction in the inner shoulder circumferential groove 31 and the groove wall angle B of the groove wall 31a located outward in the vehicle mounting direction satisfy the relationship A>B. In other words, since the groove wall angle A of the inner shoulder circumferential groove 31 is large, the volume inside the inner shoulder circumferential groove 31 is smaller than when the magnitude of the groove wall angle A is equal to or smaller than the groove wall angle B. Therefore, the amount of air in the inner shoulder circumferential groove 31 is reduced, and therefore, even if the inner shoulder circumferential groove 31 elastically deforms and the air in the inner shoulder circumferential groove 31 vibrates, the volume of the air column resonance in the inner shoulder circumferential groove 31 can be suppressed due to the small amount of air. This can improve the NV performance.

[0093] On the other hand, since the groove wall angle B of the groove wall 31a located toward the outer side in the vehicle mounting direction is within a range of 8° to 12°, the volume of the inner shoulder circumferential groove 31 can be prevented from becoming too small. This ensures the drainage performance of the inner shoulder circumferential groove 31 and ensures wet performance. Furthermore, since the groove wall angle A of the inner shoulder circumferential groove 31 is within a range of 13° to 20°, the volume of the inner shoulder circumferential groove 31 can be reduced by an appropriate amount without impairing the drainage performance. This ensures the drainage performance of the inner shoulder circumferential groove 31 and reduces the volume of air column resonance in the inner shoulder circumferential groove 31.

[0094] Moreover, since the groove wall angle C and the groove wall angle D of the inner center circumferential groove 32 are both within the range of 8° to 12°, the volume of the inner center circumferential groove 32 can be prevented from becoming too small. This ensures the drainage performance of the inner center circumferential groove 32, and ensures the wet performance. As a result, it is possible to achieve both NV performance and wet performance.

[0095] In addition, for the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, since the groove wall angle B of the inner shoulder circumferential groove 31 and the groove wall angle C of the inner center circumferential groove 32 satisfy the relationship of -1° ≤ B - C ≤ 1°, the volume of the inner shoulder circumferential groove 31 can be appropriately suppressed, and the volume of the inner center circumferential groove 32 can be appropriately ensured. As a result, both NV performance and wet performance can be achieved simultaneously.

[0096] In addition, when the groove wall angle B of the inner shoulder circumferential groove 31 and the groove wall angle C of the inner center circumferential groove 32 satisfy the relationship of B < C, it is possible to suppress the volume of the inner center circumferential groove 32 from becoming too large. Thereby, the volume of the inner center circumferential groove 32 can also suppress the volume of the air column resonance. As a result, both NV performance and wet performance can be more reliably achieved simultaneously.

[0097] In addition, for the inner center circumferential groove 32, since the groove wall angle C and the groove wall angle D satisfy the relationship of -2° ≤ D - C ≤ 2°, the volume of the inner center circumferential groove 32 can be ensured to be of an appropriate size without the volume of the inner center circumferential groove 32 becoming too large. As a result, both NV performance and wet performance can be more reliably achieved simultaneously.

[0098] In addition, for the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, since the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 satisfy the relationship of W2 < W1, both NV performance and wet performance can be achieved simultaneously. That is, since the groove width W1 of the inner shoulder circumferential groove 31 is wider than the groove width W2 of the inner center circumferential groove 32, it is possible to suppress the volume of the inner shoulder circumferential groove 31 with a large groove wall angle A from becoming too small. Thereby, the drainage performance of the inner shoulder circumferential groove 31, which is likely to have a small volume due to a large groove wall angle A, can be ensured.

[0099] In addition, the groove width W2 of the inner center circumferential groove 32 is narrower than the groove width W1 of the inner shoulder circumferential groove 31, so that the volume of the inner center circumferential groove 32 can be minimized. This makes it possible to suppress the volume of air column resonance also in the inner center circumferential groove 32. As a result, it is possible to more reliably achieve both NV performance and wet performance.

[0100] In addition, the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 satisfy the relationship of 1.0≦W1 / W2≦1.2, so that the volume of the inner shoulder circumferential groove 31 can be appropriately reduced. In other words, when the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 are 1.0>W1 / W2, the groove width W1 of the inner shoulder circumferential groove 31 may be too narrow. In this case, the volume of the inner shoulder circumferential groove 31 may be too small, which may make it difficult to ensure the drainage performance of the inner shoulder circumferential groove 31. In addition, when the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 are W1 / W2>1.2, the groove width W1 of the inner shoulder circumferential groove 31 may be too wide. In this case, even if the groove wall angle A of the inner shoulder circumferential groove 31 is increased, it becomes difficult to reduce the volume of the inner shoulder circumferential groove 31, so there is a risk that it becomes difficult to suppress the volume of air column resonance in the inner shoulder circumferential groove 31.

[0101] In contrast, when the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32 satisfy the relationship 1.0≦W1 / W2≦1.2, the volume of the inner shoulder circumferential groove 31 can be appropriately reduced by increasing the groove wall angle A while preventing the volume of the inner shoulder circumferential groove 31 from becoming too small. This ensures the drainage performance of the inner shoulder circumferential groove 31 while reducing the volume of the air column resonance in the inner shoulder circumferential groove 31. As a result, it is possible to more reliably achieve both the NV performance and the wet performance.

[0102] Furthermore, since the sipes 50 are disposed in the inner shoulder land portion 21 and the inner intermediate land portion 22, drainage can be ensured by the sipes 50 without reducing the rigidity of the inner shoulder land portion 21 and the inner intermediate land portion 22, which are disposed on both sides in the tire width direction of the inner shoulder circumferential groove 31. As a result, it is possible to achieve both NV performance and wet performance, and to improve wear resistance by ensuring the rigidity of the land portion 20.

[0103] Moreover, the sipes 50 arranged in the inner shoulder land portion 21, the inner intermediate land portion 22, and the center land portion 23 have sipes 50 that communicate with the circumferential grooves 30 via the cutouts 60. This ensures the rigidity of the land portion 20 while improving the flow of water between the sipes 50 and the circumferential grooves 30 through the cutouts 60, thereby improving drainage. As a result, it is possible to achieve both NV performance and wet performance, and improve wear resistance.

[0104] In addition, the maximum length Dc1 of the inner shoulder cutout 61 is within the range of 0.10≦Dc1 / Wb1≦0.15 with respect to the ground contact width Wb1 of the inner shoulder land portion 21, and the maximum length Dc2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is within the range of 0.35≦Dc2 / Wb2≦0.45 with respect to the ground contact width Wb2 of the inner intermediate land portion 22. Therefore, drainage performance can be ensured without reducing the rigidity of the inner shoulder land portion 21 or the inner intermediate land portion 22.

[0105] In other words, when the maximum length Dc1 of the inner shoulder cutout 61 is 0.10>Dc1 / Wb1 relative to the ground contact width Wb1 of the inner shoulder land portion 21, the length of the inner shoulder cutout 61 is too short, so it may be difficult to improve drainage even if the inner shoulder cutout 61 is provided in the inner shoulder land portion 21. Similarly, when the maximum length Dc2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is 0.35>Dc2 / Wb2 relative to the ground contact width Wb2 of the inner intermediate land portion 22, the length of the inner intermediate cutout 62 is too short, so it may be difficult to improve drainage even if the inner intermediate cutout 62 is provided in the inner intermediate land portion 22.

[0106] Furthermore, when the maximum length Dc1 of the inner shoulder cutout 61 is Dc1 / Wb1>0.15 with respect to the ground contact width Wb1 of the inner shoulder land portion 21, the length of the inner shoulder cutout 61 is too long, which may reduce the rigidity of the inner shoulder land portion 21 and make it difficult to ensure the NV performance and wear resistance. Similarly, when the maximum length Dc2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is Dc2 / Wb2>0.45 with respect to the ground contact width Wb2 of the inner intermediate land portion 22, the length of the inner intermediate cutout 62 is too long, which may reduce the rigidity of the inner intermediate land portion 22 and make it difficult to ensure the NV performance and wear resistance.

[0107] In contrast to this, when the maximum length Dc1 of the inner shoulder cutout 61 is within a range of 0.10≦Dc1 / Wb1≦0.15 relative to the ground contact width Wb1 of the inner shoulder land portion 21, or the maximum length Dc2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is within a range of 0.35≦Dc2 / Wb2≦0.45 relative to the ground contact width Wb2 of the inner intermediate land portion 22, drainage can be ensured by the inner shoulder cutout 61 and the inner intermediate cutout 62 without reducing the rigidity of the inner shoulder land portion 21 and the inner intermediate land portion 22. As a result, wet performance can be improved while ensuring NV performance and wear resistance.

[0108] In addition, since the relationship between the maximum length Dc2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 and the maximum length Dc3 of the inner intermediate cutout 62 communicating with the inner center circumferential groove 32 is within the range of 1.1≦Dc2 / Dc3≦1.5, it is possible to facilitate the flow of water toward the inner shoulder circumferential groove 31 while suppressing the rigidity of the inner intermediate land portion 22 from being biased on both sides in the tire width direction. This makes it possible to facilitate the flow of water toward the inner shoulder circumferential groove 31 having a wide groove width while suppressing deterioration of wear resistance caused by the bias in the rigidity of the inner intermediate land portion 22, thereby improving drainage. As a result, it is possible to improve wet performance while ensuring wear resistance.

[0109] In addition, the maximum depth h1 of the inner shoulder cutout 61 is within the range of 0.45≦h1 / Hs≦0.55 relative to the maximum depth Hs of the inner shoulder circumferential groove 31, and the maximum depth h2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is within the range of 0.55≦h2 / Hs≦0.65 relative to the maximum depth Hs of the inner shoulder circumferential groove 31. Therefore, drainage performance can be ensured without reducing the rigidity of the inner shoulder land portion 21 or the inner intermediate land portion 22.

[0110] In other words, when the maximum depth h1 of the inner shoulder cutout 61 is 0.45>h1 / Hs relative to the maximum depth Hs of the inner shoulder circumferential groove 31, the depth of the inner shoulder cutout 61 is too shallow, so there is a concern that it will be difficult to improve drainage even if the inner shoulder cutout 61 is provided in the inner shoulder land portion 21. Similarly, when the maximum depth h2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is 0.55>h2 / Hs relative to the maximum depth Hs of the inner shoulder circumferential groove 31, the depth of the inner intermediate cutout 62 is too shallow, so there is a concern that it will be difficult to improve drainage even if the inner intermediate cutout 62 is provided in the inner intermediate land portion 22.

[0111] Furthermore, when the maximum depth h1 of the inner shoulder cutout 61 is relative to the maximum depth Hs of the inner shoulder circumferential groove 31, such that h1 / Hs>0.55, the inner shoulder cutout 61 is too deep, which reduces the rigidity of the inner shoulder land portion 21 and may make it difficult to ensure the NV performance and wear resistance. Similarly, when the maximum depth h2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is relative to the maximum depth Hs of the inner shoulder circumferential groove 31, such that h2 / Hs>0.65, the inner intermediate cutout 62 is too deep, which reduces the rigidity of the inner intermediate land portion 22 and may make it difficult to ensure the NV performance and wear resistance.

[0112] In contrast to this, when the maximum depth h1 of the inner shoulder cutout 61 is within a range of 0.45≦h1 / Hs≦0.55 relative to the maximum depth Hs of the inner shoulder circumferential groove 31, or the maximum depth h2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 is within a range of 0.55≦h2 / Hs≦0.65 relative to the maximum depth Hs of the inner shoulder circumferential groove 31, drainage performance can be ensured by the inner shoulder cutout 61 and the inner intermediate cutout 62 without reducing the rigidity of the inner shoulder land portion 21 and the inner intermediate land portion 22. As a result, wet performance can be improved while ensuring NV performance and wear resistance.

[0113] In addition, since the relationship between the maximum depth h2 of the inner intermediate cutout 62 communicating with the inner shoulder circumferential groove 31 and the maximum depth h3 of the inner intermediate cutout 62 communicating with the inner center circumferential groove 32 is within the range of 0.99≦h2 / h3≦1.01, it is possible to suppress the rigidity of the inner intermediate land portion 22 from being biased on both sides in the tire width direction. As a result, while suppressing deterioration of wear resistance caused by bias in the rigidity of the inner intermediate land portion 22, the inner intermediate cutout 62 can facilitate the flow of water to the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, thereby improving drainage. As a result, it is possible to improve wet performance while ensuring wear resistance.

[0114] Furthermore, the width of the notch 60 communicating with the sipe 50 in the tire circumferential direction is within a range of 7 to 13 times the width of the sipe 50 communicating with the notch 60 in the tire circumferential direction, so that the drainage can be improved while preventing the rigidity of the land portion 20 from becoming too low. In other words, if the width of the notch 60 is less than 7 times the width of the sipe 50, the width of the notch 60 is too narrow, so that even if the notch 60 is provided in the land portion 20, it may be difficult to improve the drainage. Furthermore, if the width of the notch 60 is more than 13 times the width of the sipe 50, the width of the notch 60 is too wide, so that there is a risk that the rigidity of the land portion 20 in which the notch 60 is arranged may become too low.

[0115] In contrast, when the width of the cutout 60 is within a range of 7 to 13 times the width of the sipe 50, the drainage can be improved by the cutout 60 while preventing the rigidity of the land portion 20 where the cutout 60 is arranged from becoming too low. As a result, the wet performance can be improved while ensuring the wear resistance.

[0116] In addition, the inner intermediate cutouts 62 arranged in the inner intermediate land portion 22 are arranged such that the inner intermediate cutouts 62 communicating with the inner shoulder circumferential groove 31 and the inner intermediate cutouts 62 communicating with the inner center circumferential groove 32 are alternately arranged in the tire circumferential direction. Therefore, when the vehicle is traveling, the period when the part of the inner intermediate land portion 22 where the inner intermediate cutouts 62 are arranged comes into contact with the ground can be dispersed, and pitch noise can be reduced. As a result, the NV performance can be improved.

[0117] In addition, since the inner shoulder sipes 51 arranged in the inner shoulder land portion 21 have a three-dimensional shape, it is possible to arrange the sipes 50 in the inner shoulder land portion 21 while suppressing a decrease in the rigidity of the inner shoulder land portion 21. As a result, it is possible to improve wet performance while ensuring wear resistance.

[0118] In addition, the tread portion 2 has a cap tread 4 with a tan δ at 0° C. in the range of 0.88 to 0.94 and a rubber hardness in the range of 58 to 63, so that the running performance on wet roads can be improved while ensuring the rigidity of the land portion 20. As a result, the wet performance can be improved while ensuring the wear resistance.

[0119] In addition, the tread pattern of the tread portion 2 is asymmetric, and the outer shoulder land portion 25 has a plurality of outer shoulder sipes 55 arranged in the tire circumferential direction, which do not have lug grooves and extend in the tire width direction, so that the outer shoulder sipes 55 can improve drainage while ensuring the rigidity of the outer shoulder land portion 25. As a result, wet performance can be improved while ensuring NV performance and wear resistance.

[0120] In addition, the groove width of the four circumferential grooves 30 narrows from the inside to the outside in the vehicle mounting direction, so that the groove width of the circumferential grooves 30 on the outside in the vehicle mounting direction, where the sound of air column resonance in the circumferential grooves 30 tends to leak to the outside of the vehicle when the vehicle is running, can be narrowed. This makes it possible to suppress the volume of air column resonance in the circumferential grooves 30 where the sound of air column resonance tends to leak to the outside of the vehicle, and improves the NV performance. In addition, since the groove width of the circumferential grooves 30 is wider at the position closer to the inside in the vehicle mounting direction than at the position closer to the outside in the vehicle mounting direction, the narrowed groove width of the circumferential grooves 30 on the outside in the vehicle mounting direction can be compensated for by the circumferential grooves 30 on the inside in the vehicle mounting direction. This makes it possible to compensate for the drainage performance when the groove width of the circumferential grooves 30 on the outside in the vehicle mounting direction is narrowed by the circumferential grooves 30 on the inside in the vehicle mounting direction. As a result, it is possible to achieve both NV performance and wet performance.

[0121] [Variations] In the above embodiment, four circumferential grooves 30 are arranged in the tread portion 2, but the number of circumferential grooves 30 arranged in the tread portion 2 may be other than four. The number of circumferential grooves 30 arranged in the tread portion 2 may be three or five.

[0122] In the above-described embodiment, the inner center circumferential groove 32 adjacent to the inner shoulder circumferential groove 31 arranged at the innermost position in the vehicle mounting direction is located on the inner side of the tire equatorial plane CL in the vehicle mounting direction, but the inner center circumferential groove 32 may be located on a side other than the inner side of the tire equatorial plane CL in the vehicle mounting direction. The inner center circumferential groove 32 may be located on the tire equatorial plane CL, for example. Regardless of the position of the inner center circumferential groove 32, the groove wall angles A, B, C, and D between the inner shoulder circumferential groove 31 and the inner center circumferential groove 32, which are the two circumferential grooves 30 counting from the inside in the vehicle mounting direction, satisfy the requirements defined in the above-described embodiment, thereby making it possible to achieve both NV performance and wet performance.

[0123] The above-described embodiments and modified examples may be combined as appropriate. In the above-described embodiments, the pneumatic tire 1 has been used as an example of the tire according to the present invention, but the tire according to the present invention may be something other than the pneumatic tire 1. The tire according to the present invention may be, for example, a so-called airless tire that can be used without filling with gas.

[0124] [Example] 6A to 6C are tables showing the results of performance evaluation tests of pneumatic tires. Hereinafter, performance evaluation tests conducted on a conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and a comparative pneumatic tire compared to the pneumatic tire 1 according to the present invention will be described for the above pneumatic tire 1. The performance evaluation tests were conducted on wet grip performance, NV performance, and abrasion resistance.

[0125] The performance evaluation test was performed by mounting a pneumatic tire 1 having a tire nominal size of 235 / 50R18 97W as specified by JATMA on a JATMA standard rim wheel having a rim size of 18 x 7.5J, mounting the test tire on a 2WD minivan-type evaluation vehicle, adjusting the air pressure to 230 kPa for the front wheels and 240 kPa for the rear wheels, and running the evaluation vehicle.

[0126] The method of evaluation for each test item was as follows: for wet grip performance, a test driver drove an evaluation vehicle equipped with a test tire on a test course with a road surface conforming to R117, and the wet grip performance was measured based on the μ-s characteristics. The wet grip performance was evaluated by expressing the measured wet grip performance as an index with the conventional example described below being 100, and the higher the index, the better the wet grip performance. Note that if the index is 98 or higher, the wet grip performance is maintained at the same level as the conventional example, and wet grip performance that is comparable to the conventional example is ensured.

[0127] The NV performance was evaluated by having a test driver drive an evaluation vehicle fitted with the test tires around a test course and measuring the noise energy at the driver's inner ear. The NV performance was evaluated by expressing the reciprocal of the measured noise energy as an index, with the conventional example described below being set at 100, and the higher the index, the better the NV performance.

[0128] The wear resistance was evaluated by measuring the groove depth after a road test of 8000 km was conducted by a test driver using an evaluation vehicle fitted with the test tires. The wear resistance was evaluated by expressing the measured groove depth as an index, with the conventional example described below being set at 100, and the higher the index, the better the wear resistance.

[0129] The performance evaluation test was carried out on 21 types of pneumatic tires, including a conventional pneumatic tire which is an example of a conventional pneumatic tire, Examples 1 to 17 which are pneumatic tire 1 according to the present invention, and Comparative Examples 1 to 3 which are pneumatic tires compared with pneumatic tire 1 according to the present invention. Of these, the conventional example and Comparative Example 3 have the same groove wall angle A and groove wall angle B of the inner shoulder circumferential groove. Also, in Comparative Examples 1 and 2, the groove wall angle A of the inner shoulder circumferential groove is smaller than the groove wall angle B.

[0130] In contrast, in all of Examples 1 to 17, which are examples of the pneumatic tire 1 according to the present invention, the groove wall angle A of the inner shoulder circumferential groove 31 is greater than the groove wall angle B. Furthermore, the pneumatic tires 1 according to Examples 1 to 17 are different in the groove wall angles A and B of the inner shoulder circumferential groove 31, the groove wall angles C and D of the inner center circumferential groove 32, a comparison between the groove width W1 of the inner shoulder circumferential groove 31 and the groove width W2 of the inner center circumferential groove 32, the grooves arranged in the inner shoulder land portion 21 and the inner intermediate land portion 22, the communication between the sipes 50 and the cutouts 60 in the inner shoulder land portion 21 and the inner intermediate land portion 22, the length and depth of the cutouts 60, the width of the cutouts 60 relative to the width of the sipes 50, the shape of the sipes 50 in the inner shoulder land portion 21, the tan δ and rubber hardness of the cap tread 4, and the relative relationship between the groove width of the circumferential grooves.

[0131] As a result of carrying out a performance evaluation test using these pneumatic tires 1, it was found that the pneumatic tires 1 according to Examples 1 to 17 can improve the NV performance while minimizing the decrease in wet grip performance compared to the conventional tire, and can improve both the wet grip performance and the NV performance compared to the comparative example, as shown in Figures 6A to 6C. In other words, the pneumatic tires 1 according to Examples 1 to 17 can achieve both the NV performance and the wet performance.

[0132] The present disclosure includes the following inventions. Invention[1] A plurality of circumferential grooves extending in a circumferential direction of the tire are provided, Among the plurality of circumferential grooves, the innermost circumferential groove in the vehicle mounting direction is an inner shoulder circumferential groove, When the circumferential groove adjacent to the inner shoulder circumferential groove in the tire width direction is an inner center circumferential groove, The inner shoulder circumferential groove is located on the inner side of the tire equatorial plane in a vehicle mounting direction, the inner center circumferential groove is located on the inner side of the tire equatorial plane in the vehicle mounting direction or on the tire equatorial plane, of the inner shoulder circumferential groove, a groove wall angle A of the groove wall located on the inner side in the vehicle mounting direction with respect to the tire radial direction, and a groove wall angle B of the groove wall located on the outer side in the vehicle mounting direction with respect to the tire radial direction satisfy a relationship of A>B, and the groove wall angle A is within a range of 13° or more and 20° or less, and the groove wall angle B is within a range of 8° or more and 12° or less, The inner center circumferential groove is characterized in that, of a pair of groove walls opposing each other in the tire width direction, a groove wall angle C relative to the tire radial direction of the groove wall located closer to the inner side in the vehicle mounting direction and a groove wall angle D relative to the tire radial direction of the groove wall located closer to the outer side in the vehicle mounting direction are both within a range of 8° to 12°. Invention[2] The tire according to invention [1], wherein the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy the relationship of -1° ≤ B - C ≤ 1°. Invention [3] The tire according to invention [1] or invention [2], wherein the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy the relationship of B < C. Invention [4] The tire according to any one of inventions [1] to [3], wherein in the inner center circumferential groove, the groove wall angle C and the groove wall angle D satisfy the relationship of -2° ≤ D - C ≤ 2°. Invention [5] The tire according to any one of inventions [1] to [4], wherein the inner shoulder circumferential groove and the inner center circumferential groove satisfy the relationship of W2 < W1, where W1 is the groove width of the inner shoulder circumferential groove and W2 is the groove width of the inner center circumferential groove. Invention [6] The tire according to invention [5], wherein the groove width W1 of the inner shoulder circumferential groove and the groove width W2 of the inner center circumferential groove satisfy the relationship of 1.0 ≤ W1 / W2 ≤ 1.2. Invention [7] Comprising a plurality of land portions partitioned by the circumferential groove, Among the plurality of land portions, an inner shoulder land portion, the inner side in the tire width direction of which is the land portion partitioned by the inner shoulder circumferential groove, and an inner intermediate land portion, both sides in the tire width direction of which are the land portions partitioned by the inner shoulder circumferential groove and the inner center circumferential groove, have sipes disposed therein, according to any one of inventions [1] to [6]. Invention [8] The sipes disposed in the inner intermediate land portion include sipes that communicate with both the inner shoulder circumferential groove and the inner center circumferential groove and communicate with the inner shoulder circumferential groove via notches, and sipes that communicate with the inner center circumferential groove via notches. the sipes arranged in the inner shoulder land portion extend in the tire width direction across the ground contact edge and communicate with the inner shoulder circumferential groove, and at least some of the sipes arranged in the inner shoulder land portion communicate with the inner shoulder circumferential groove via a cutout portion, A tire as described in invention [7], in which a sipe communicating with the inner center circumferential groove via a cutout portion is disposed in a center land portion, which is a land portion among the plurality of land portions located on the opposite side of the inner center circumferential groove in the tire width direction to the side where the inner intermediate land portion is located and is defined by the inner center circumferential groove. Inventions[9] the cutout portion that is disposed in the inner shoulder land portion and communicates with the inner shoulder circumferential groove has a maximum length Dc1 in the tire width direction, where Dc1 is a ground contact width Wb1 of the inner shoulder land portion, within a range of 0.10≦Dc1 / Wb1≦0.15, the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove has a maximum length Dc2 in the tire width direction, with respect to a ground contact width Wb2 of the inner intermediate land portion, within a range of 0.35≦Dc2 / Wb2≦0.45, The tire according to invention [8], wherein the relationship between a maximum length Dc2 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and a maximum length Dc3 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 1.1≦Dc2 / Dc3≦1.5. Inventions

[10] the cutout portion disposed in the inner shoulder land portion and communicating with the inner shoulder circumferential groove has a maximum depth h1 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.45≦h1 / Hs≦0.55, the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove has a maximum depth h2 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.55≦h2 / Hs≦0.65, The tire according to invention [8] or [9], wherein a relationship between a maximum depth h2 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and a maximum depth h3 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 0.99≦h2 / h3≦1.01. Inventions

[11] The tire according to any one of inventions [8] to

[10] , wherein the width in the tire circumferential direction of the cutout portion to which the sipes are connected is within a range of 7 to 13 times the width in the tire circumferential direction of the sipes communicating with the cutout portion. Inventions

[12] The tire according to any one of inventions [8] to

[11] , wherein the cutouts arranged in the inner intermediate land portion are arranged such that the cutouts communicating with the inner shoulder circumferential groove and the cutouts communicating with the inner center circumferential groove are alternately arranged in the tire circumferential direction. Inventions

[13] The tire according to any one of inventions [7] to

[12] , wherein the sipe arranged in the inner shoulder land portion has a three-dimensional shape. Inventions

[14] The tire according to any one of the inventions [1] to

[13] , wherein the tread portion has a cap tread having a tan δ at 0°C in the range of 0.88 to 0.94 and a rubber hardness in the range of 58 to 63. Inventions

[15] Four of the circumferential grooves are arranged, a tread pattern of a tread portion that is asymmetric on both sides of the tire equatorial plane in the tire width direction, Among the multiple land portions, an outer shoulder land portion, which is the land portion located outermost in the vehicle mounting direction, has multiple sipes arranged in a row in the tire circumferential direction without having lug grooves and extending in the tire width direction. A tire as described in any one of Inventions [1] to

[14] . Inventions

[16] The tire according to the invention

[15] , wherein the four circumferential grooves have a groove width that narrows from the inside to the outside in the vehicle mounting direction. [Explanation of symbols]

[0133] 1. Pneumatic tires 2 Tread section 3 Tread contact surface 4 Cap Tread 5 Shoulder section 8 Sidewall 10 Bead section 13 Carcass layer 14 Belt layer 20 Land 21 Inner shoulder land area 22 Inner intermediate land area 23 Center Land Section 24 Outer intermediate land area 25 Outer shoulder land area 25a First outer shoulder land area 25b Second outer shoulder land part 30 Circumferential groove 31 Inner shoulder circumferential groove 31a, 32a groove wall 32 Inner center circumferential groove 33 Outer center circumferential groove 34 Outer shoulder circumferential groove 40 Circumferential narrow groove 50 sipes 51 Inner shoulder sipe 52 Inner middle sipe 53 Center sipe 54 Outer intermediate sipe 55 Outer shoulder sipes 60 Notch 61 Inner shoulder cutout 62 Inner intermediate cutout 63 Center cutout 64 Outer intermediate cutout 65 Outer shoulder cutout

Claims

1. A plurality of circumferential grooves extending in a circumferential direction of the tire are provided, Among the plurality of circumferential grooves, the innermost circumferential groove in the vehicle mounting direction is an inner shoulder circumferential groove, When the circumferential groove adjacent to the inner shoulder circumferential groove in the tire width direction is an inner center circumferential groove, The inner shoulder circumferential groove is located on the inner side of the tire equatorial plane in a vehicle mounting direction, the inner center circumferential groove is located on the inner side of the tire equatorial plane in the vehicle mounting direction or on the tire equatorial plane, the inner shoulder circumferential groove has a pair of groove walls opposing each other in the tire width direction, the groove wall angle A relative to the tire radial direction of the groove wall located closer to the inner side in the vehicle mounting direction and the groove wall angle B relative to the tire radial direction of the groove wall located closer to the outer side in the vehicle mounting direction satisfying a relationship of A>B, the groove wall angle A being within a range of 13° or more and 20° or less, and the groove wall angle B being within a range of 8° or more and 12° or less, a groove wall angle C of the inner center circumferential groove relative to the tire radial direction of the groove wall located closer to the inner side in the vehicle mounting direction, and a groove wall angle D of the inner center circumferential groove relative to the tire radial direction of the groove wall located closer to the outer side in the vehicle mounting direction, both of which are within a range of 8° to 12°.

2. The tire according to claim 1, wherein the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy a relationship of -1°≦B−C≦1°.

3. The tire according to claim 1 or 2, wherein the groove wall angle B of the inner shoulder circumferential groove and the groove wall angle C of the inner center circumferential groove satisfy a relationship of B<C.

4. The tire according to claim 1 or 2, wherein the inner center circumferential groove has a groove wall angle C and a groove wall angle D that satisfy a relationship of -2°≦D−C≦2°.

5. 3. The tire according to claim 1, wherein a groove width W1 of the inner shoulder circumferential groove and a groove width W2 of the inner center circumferential groove satisfy a relationship of W2<W1.

6. The tire according to claim 5 , wherein the groove width W1 of the inner shoulder circumferential groove and the groove width W2 of the inner center circumferential groove satisfy a relationship of 1.0≦W1 / W2≦1.

2.

7. A plurality of land portions defined by the circumferential groove are provided, 2. The tire according to claim 1, wherein sipes are arranged in an inner shoulder land portion, which is a land portion whose inner side in the tire width direction is defined by the inner shoulder circumferential groove, and an inner intermediate land portion, which is a land portion whose both sides in the tire width direction are defined by the inner shoulder circumferential groove and the inner center circumferential groove, among the plurality of land portions.

8. the sipe disposed in the inner intermediate land portion communicates with both the inner shoulder circumferential groove and the inner center circumferential groove, and includes the sipe communicating with the inner shoulder circumferential groove through a cutout portion and the sipe communicating with the inner center circumferential groove through a cutout portion, the sipes arranged in the inner shoulder land portion extend in the tire width direction across the ground contact edge and communicate with the inner shoulder circumferential groove, and at least some of the sipes arranged in the inner shoulder land portion communicate with the inner shoulder circumferential groove via a cutout portion, 8. The tire according to claim 7, wherein a sipe communicating with the inner center circumferential groove via a cutout is disposed in a center land portion, which is a land portion among the plurality of land portions and is located on the opposite side of the inner center circumferential groove in the tire width direction to the side where the inner intermediate land portion is located and is partitioned by the inner center circumferential groove.

9. the cutout portion that is disposed in the inner shoulder land portion and communicates with the inner shoulder circumferential groove has a maximum length Dc1 in the tire width direction, with respect to a ground contact width Wb1 of the inner shoulder land portion, within a range of 0.10≦Dc1 / Wb1≦0.15, the cutout portion that is disposed in the inner intermediate land portion and communicates with the inner shoulder circumferential groove has a maximum length Dc2 in the tire width direction, with respect to a ground contact width Wb2 of the inner intermediate land portion, within a range of 0.35≦Dc2 / Wb2≦0.45, 9. The tire according to claim 8, wherein a relationship between a maximum length Dc2 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and a maximum length Dc3 in the tire width direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 1.1≦Dc2 / Dc3≦1.

5.

10. the cutout portion that is disposed in the inner shoulder land portion and communicates with the inner shoulder circumferential groove has a maximum depth h1 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.45≦h1 / Hs≦0.55, the cutout portion that is disposed in the inner intermediate land portion and communicates with the inner shoulder circumferential groove has a maximum depth h2 in the tire radial direction, relative to a maximum depth Hs of the inner shoulder circumferential groove, within a range of 0.55≦h2 / Hs≦0.65, 10. The tire according to claim 8, wherein a relationship between a maximum depth h2 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner shoulder circumferential groove and a maximum depth h3 in the tire radial direction of the cutout portion disposed in the inner intermediate land portion and communicating with the inner center circumferential groove is within a range of 0.99≦h2 / h3≦1.

01.

11. The tire according to claim 8 , wherein the cutout portion to which the sipe is connected has a width in the tire circumferential direction that is in the range of 7 to 13 times the width in the tire circumferential direction of the sipe to which the cutout portion is connected.

12. 9. The tire according to claim 8, wherein the cutouts arranged in the inner intermediate land portion are arranged such that the cutouts communicating with the inner shoulder circumferential groove and the cutouts communicating with the inner center circumferential groove are alternately arranged in the tire circumferential direction.

13. The tire according to claim 7 or 8, wherein the sipe disposed in the inner shoulder land portion has a three-dimensional shape.

14. 2. The tire according to claim 1, wherein the tread portion has a cap tread having a tan δ at 0° C. in the range of 0.88 to 0.94 and a rubber hardness in the range of 58 to 63.

15. Four of the circumferential grooves are arranged, a tread pattern of a tread portion that is asymmetric on both sides of the tire equatorial plane in the tire width direction, The tire according to claim 7, wherein an outer shoulder land portion, which is the land portion located outermost in the vehicle mounting direction among the plurality of land portions, has a plurality of sipes extending in the tire width direction without having lug grooves and arranged side by side in the tire circumferential direction.

16. The tire according to claim 15, wherein the four circumferential grooves have a groove width that narrows from the inner side toward the outer side in the vehicle mounting direction.

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