tire

Abstract

To provide a tire in which dry performance, wet performance, and snow performance can be all achieved at high level.SOLUTION: In a tire, at least one main groove 10 has a groove wall angle β in a vehicle inner side set to be smaller than a groove wall angle α in a vehicle outer side. A center land part 20 positioned on a tire equator CL, a pair of intermediate land parts 30, and a pair of shoulder land parts 40 are included. A shoulder lug groove 42 formed in at least one of the shoulder land parts 40 communicates with the main groove 10. The intermediate land part 30 includes: a plurality of intermediate lug grooves 32 each of which has one end opening to the main groove 10 and another end terminating within the intermediate land part 30; a plurality of first sipings 33A each of which has one end opening to the main groove 10 to which the intermediate lug groove 32 opens and another end opening to the intermediate lug groove 32; and a plurality of second sipings 33B each of which has one end opening to the main groove 10 positioned opposite to the main groove 10 to which the intermediate lug groove 32 opens and another end opening to the intermediate lug groove 32. Each of the first siping 33A and the second siping 33B has a chamfer part 34 at only one of a stepping side edge and a kicking side edge.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire having multiple rows of land portions defined by multiple main grooves in the tread portion, and more specifically to a tire that is capable of achieving high levels of dry performance, wet performance, and snow performance all at the same time. [Background technology]

[0002] Some pneumatic tires have a tread pattern in which multiple main grooves extending in the tire circumferential direction are formed in the tread portion, and multiple lug grooves and sipes extending in the tire width direction are formed in each land portion defined by these main grooves (see, for example, Patent Document 1).

[0003] Such pneumatic tires are required to exhibit excellent wet and snow performance based on groove components including main grooves, lug grooves, and sipes, while also maintaining good dry performance. In particular, all-season tires are required to achieve high levels of dry performance, wet performance, and snow performance. However, since dry performance is a contradictory performance to wet performance and snow performance, it is difficult to achieve high levels of both. Therefore, further improvements are desired to satisfy the performance requirements of the market. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 024593 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a tire that can achieve high levels of dry performance, wet performance, and snow performance all at once. [Means for solving the problem]

[0006] In order to achieve the above object, a tire of the present invention has, in a tread portion, a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of land portions defined by the plurality of main grooves, and the tire is mounted in a specified direction on a vehicle, At least one of the plurality of main grooves has a groove wall angle on an inner side of the vehicle that is smaller than a groove wall angle on an outer side of the vehicle, The plurality of rows of land portions include a center land portion located on the tire equator, a pair of intermediate land portions located on both outer sides of the center land portion, and a pair of shoulder land portions located on the outer sides of each intermediate land portion, Each of the pair of shoulder land portions has a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug groove formed in at least one of the pair of shoulder land portions communicates with a main groove adjacent to the shoulder land portion, Each of the intermediate land portions has a plurality of intermediate lug grooves, one end of which opens into one of the main grooves and the other end of which terminates within the intermediate land portion, a plurality of first sipes, one end of which opens into the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, and a plurality of second sipes, one end of which opens into the main groove located on the opposite side of the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, and each of the first sipes and the second sipes is characterized in that it has a chamfered portion on only one of the leading-in edge and trailing-out edge. [Effects of the Invention]

[0007] In the present invention, the groove wall angle on the vehicle-inboard side of at least one main groove is set relatively small, thereby ensuring the volume of that main groove and improving wet and snow performance. Meanwhile, the groove wall angle on the vehicle-outboard side of at least one main groove is set relatively large, thereby suppressing the collapse of adjacent land portions in the tire width direction and improving dry performance. Furthermore, shoulder lug grooves formed in at least one shoulder land portion communicate with the main groove adjacent to that shoulder land portion, and each intermediate land portion is formed with intermediate lug grooves, first sipes, second sipes, and chamfered portions, thereby ensuring sufficient drainage and edge effects and improving wet and snow performance. As a result, dry, wet, and snow performance can be improved at a high level.

[0008] In the present invention, a tire with a specified mounting direction relative to a vehicle means a tire equipped with an indicator that indicates the mounting direction relative to a vehicle. A main groove means a circumferential groove equipped with a wear indicator, and a sipe means a groove with a groove width of 1.5 mm or less.

[0009] In the present invention, it is preferable that the groove wall angle on the innermost side of the main groove among the plurality of main grooves be equal to the groove wall angle on the inner side of the vehicle, and that the groove wall angle on the inner side of the main grooves other than the innermost main groove be smaller than the groove wall angle on the outer side of the vehicle. Because the innermost main groove is important for drainage and snow removal performance, making the groove wall angles on both sides of this main groove equal can enhance the effect of improving wet and snow performance. In this case, it is preferable that the groove wall angle on the inner side of the main groove located on the innermost side of the vehicle and the groove wall angle on the outer side of the main groove located on the innermost side of the vehicle be smaller than the groove wall angle on the outer side of the main grooves other than the innermost main groove.

[0010] Of the pair of shoulder land portions, it is preferable that the shoulder lug grooves formed in the shoulder land portion located on the vehicle inner side open into the main groove adjacent to that shoulder land portion, and the shoulder lug grooves formed in the shoulder land portion located on the vehicle outer side do not communicate with the main groove adjacent to that shoulder land portion. By having the shoulder lug grooves formed in the shoulder land portion located on the vehicle inner side open into the main groove, drainage and snow removal can be ensured, and wet and snow performance can be improved. On the other hand, by having the shoulder lug grooves formed in the shoulder land portion located on the vehicle outer side not communicate with the main groove, dry performance can be improved and further, passing noise caused by the tire can be reduced.

[0011] The chamfered portion preferably has a curved surface recessed toward the inside of the intermediate land portion, thereby increasing the drainage volume and snow removal volume, and enhancing the effect of improving wet and snow performance.

[0012] The intermediate land portion preferably has a plurality of third sipes that extend on the extension lines of the first sipes and the second sipes and that do not have chamfered portions. By mixing a plurality of third sipes that do not have chamfered portions with the first sipes and the second sipes that have chamfered portions, wet performance and snow performance can be improved, and the actual contact area of ​​the tread portion can be sufficiently secured, thereby improving dry performance.

[0013] The intermediate land portion preferably has a plurality of longitudinal sipes extending in the tire circumferential direction. By providing longitudinal sipes in the intermediate land portion, the tire circumferential edge can be secured, and cornering performance can be improved, particularly when driving on snow.

[0014] The intermediate land portion has a plurality of third sipes extending on extensions of the first sipes and the second sipes and having no chamfered portions, and a plurality of longitudinal sipes extending in the tire circumferential direction, the intermediate lug grooves having a bent shape, each having a first groove portion extending from its opening end to a bending point and a second groove portion extending from the bending point to its end, the plurality of longitudinal sipes branching from the third sipes and the intermediate lug grooves, the longitudinal sipes branching from the third sipes extending in the tire circumferential direction from a position 20% to 80% of the length of the third sipe from the opening end of the main groove of the third sipe to the third sipe and terminating in the intermediate land portion, and the longitudinal sipes branching from the intermediate lug grooves extending in the tire circumferential direction from a position within 5 mm of the bent corner of the intermediate lug groove and terminating in the intermediate land portion. By specifying the arrangement of the longitudinal sipes in the intermediate land portion in this way, it is possible to ensure a circumferential edge of the tire without impairing dry performance, and to improve cornering performance, especially when driving on snow.

[0015] The center land portion has circumferential narrow grooves extending in the tire circumferential direction, a plurality of center lug grooves each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, and a plurality of center sipes each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, wherein the inclination angle of the center lug grooves and center sipes relative to the tire circumferential direction at their opening ends is 50° to 80°, the length of the center lug grooves and center sipes in the tire width direction is 40% to 80% of the distance from the main groove to the circumferential narrow groove, and the spacing between the center lug grooves and center sipes in the tire circumferential direction is preferably 5 mm to 20 mm. By having the center land portion thus have, in addition to the circumferential narrow grooves, center lug grooves and center sipes that do not divide the center land portion, it is possible to improve wet performance without degrading dry performance.

[0016] The shoulder land portion preferably has a plurality of shoulder sipes extending in a zigzag pattern in the tire width direction and a plurality of longitudinal sipes extending from the shoulder sipes in the tire circumferential direction. By having longitudinal sipes in addition to the zigzag shoulder sipes in the shoulder land portion in this way, wet performance and snow performance can be improved.

[0017] The intermediate lug groove has a bent shape and has a first groove portion from the open end to the bending point and a second groove portion from the bending point to the end. The bending point is at a position of 60% to 90% of the width of the intermediate land portion from the open end of the intermediate lug groove, and the length La of the first groove portion and the length Lb of the second groove portion satisfy the relationship of 0.3×La < Lb < 0.8La, and the angle θ formed by the first groove portion and the second groove portion at the bending point is preferably in the range of 0° < θ < 90°. By having the intermediate lug groove with a predetermined bent shape in this way, the traction effect during running increases, and dry performance and wet performance can be improved.

[0018] The tire of the present invention is preferably a pneumatic tire, but may also be a non-pneumatic tire. In the case of a pneumatic tire, it can be filled with air, an inert gas such as nitrogen, or other gases inside.

Brief Description of the Drawings

[0019] [Figure 1] It is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] It is a developed view showing the tread pattern of the pneumatic tire of FIG. 1. [Figure 3] It is a contour view showing the contour of the tread portion of the pneumatic tire of FIG. 1 in the meridian cross-section. [Figure 4] It is a plan view showing the main part of the tread pattern of the pneumatic tire of FIG. 1. [Figure 5] It is a cross-sectional view taken along the V-V arrow direction of FIG. 4.

Modes for Carrying Out the Invention

[0020] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Figures 1 to 5 show a pneumatic tire according to an embodiment of the present invention. This pneumatic tire is a tire in which the orientation of the front and back of the tire when mounted on a vehicle is specified. In Figures 1 to 3, IN indicates the inside of the vehicle when mounted on the vehicle, and OUT indicates the outside of the vehicle when mounted on the vehicle.

[0021] As shown in Fig. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending circumferentially in an annular shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed radially inward of the sidewall portions 2. For example, at least the sidewall portion 2 on the outer side of the vehicle is formed with a mounting direction indicator 2a indicating the mounting direction relative to the vehicle. The mounting direction indicator 2a displays, for example, "OUTSIDE" along the tire circumferential direction on the outer side of the vehicle, and displays, for example, "INSIDE" along the tire circumferential direction on the inner side of the vehicle.

[0022] A carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0023] On the other hand, multiple belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to a range of 10° to 40°, for example. Steel cords are preferably used as the reinforcing cords of the belt layers 7. At least one belt cover layer 8 is arranged on the outer peripheral side of the belt layer 7, with the aim of improving high-speed durability, and the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0024] The above-described tire internal structure is a typical example of a pneumatic tire, but is not limited to this.

[0025] As shown in Fig. 2, a plurality of main grooves 10 extending in the tire circumferential direction are formed in the tread portion 1. The main grooves 10 have a groove width in the range of 7 mm to 23 mm and a groove depth in the range of 3 mm to 12 mm, for example. These main grooves 10 include a pair of center main grooves 11, 11 located on both sides of the tire equator CL, and a pair of shoulder main grooves 12, 12 located outside each center main groove 11.

[0026] As shown in FIG. 3, when the groove wall angle of the main groove 10 on the vehicle-outside side is α and the groove wall angle of the main groove 10 on the vehicle-inside side is β, at least one of the main grooves 10 has the groove wall angle β on the vehicle-inside side set to be smaller than the groove wall angle α on the vehicle-outside side. The groove wall angles α and β are the inclination angles of the side walls of the main groove 10 with respect to a line that passes through the edge of the main groove 10 on the tread surface of the tread portion 1 and is perpendicular to the tread surface of the tread portion 1 in a tire meridian cross section. The groove wall angles α and β are selected, for example, from a range of 2° to 40°. Furthermore, when the groove wall angle β on the vehicle-inside side is made smaller than the groove wall angle α on the vehicle-outside side, the angle difference (α - β) is preferably set to be 4° to 20°.

[0027] The tread portion 1 is divided by a plurality of main grooves 10 into a center land portion 20 located on the tire equator CL, a pair of intermediate land portions 30, 30 located on both sides of the center land portion 20, and a pair of shoulder land portions 40 located on the outside of each intermediate land portion 30.

[0028] The center land portion 20 is formed with a circumferential narrow groove 21 extending in the tire circumferential direction, a plurality of center lug grooves 22 each having one end opening into the center main groove 11 adjacent to the center land portion 20 and the other end terminating within the center land portion 20, and a plurality of center sipes 23 each having one end opening into the center main groove 11 adjacent to the center land portion 20 and the other end terminating within the center land portion 20. The circumferential narrow grooves 21 have a groove width in the range of 6% to 16% of the groove width of the main groove 10 and a groove depth in the range of 25% to 60% of the groove depth of the main groove 10, for example. The center lug grooves 22 and center sipes 23 are arranged regularly or irregularly in a mixed manner along the tire circumferential direction and at intervals along the tire circumferential direction.

[0029] Each intermediate land portion 30 is formed with a plurality of intermediate lug grooves 32, one end of which opens into the shoulder main groove 12 and the other end of which terminates within the intermediate land portion 30; a plurality of first sipes 33A, one end of which opens into the shoulder main groove 12 into which the intermediate lug grooves 32 open and the other end of which opens into the intermediate lug groove 32; and a plurality of second sipes 33B, one end of which opens into the center main groove 11 located on the opposite side of the shoulder main groove 12 into which the intermediate lug grooves 32 open and the other end of which opens into the intermediate lug groove 32. The intermediate lug groove 32 has a curved shape and includes a first groove portion 32A extending from its opening end P1 to a bending point P2 and a second groove portion 32B extending from the bending point P2 to a terminal end P3 (see FIG. 4). One end of the intermediate lug groove 32 may open into the center main groove 11. Each of the first sipes 33A and the second sipes 33B has a chamfered portion 34 on only one of the leading edge (one side in the tire circumferential direction) and trailing edge (the other side in the tire circumferential direction).

[0030] Each intermediate land portion 30 is formed with a plurality of third sipes 33C that extend on extensions of the first sipes 33A and the second sipes 33B and have no chamfered portions, and a plurality of longitudinal sipes 35 that extend in the tire circumferential direction. One end of each of the third sipes 33C opens into the shoulder main groove 12 into which the intermediate lug groove 32 opens, and the other end opens into the intermediate lug groove 32. Each of the longitudinal sipes 35 branches off from the third sipes 33C or the intermediate lug groove 32.

[0031] Each shoulder land portion 40 has a plurality of shoulder lug grooves 42 formed therein, extending in the tire width direction. The shoulder lug grooves 42 formed in at least one of the shoulder land portions 40 communicate with the shoulder main groove 12 adjacent to the shoulder land portion 40. In FIG. 2 , the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle inner side open to the shoulder main groove 12, while the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle outer side do not communicate with the shoulder main groove 12.

[0032] In addition, each shoulder land portion 40 is formed with a plurality of longitudinal grooves 41 connecting a pair of shoulder lug grooves 42, 42 adjacent to each other in the tire circumferential direction, a plurality of shoulder sipes 43 extending in a zigzag pattern in the tire width direction, and a plurality of longitudinal sipes 45 extending from the shoulder sipes 43 in the tire circumferential direction.

[0033] In the pneumatic tire described above, the groove wall angle β on the vehicle-inboard side of at least one main groove 10 is set relatively small, thereby ensuring the volume of the main groove 10 and improving wet and snow performance. Meanwhile, the groove wall angle α on the vehicle-outboard side of at least one main groove 10 is set relatively large, thereby suppressing collapse of the adjacent land portion 20, 30, or 40 in the tire width direction and improving dry performance. Furthermore, the shoulder lug grooves 42 formed in at least one shoulder land portion 40 communicate with the shoulder main groove 12, and each intermediate land portion 30 is formed with an intermediate lug groove 32, a first sipe 33A, a second sipe 33B, and a chamfered portion 34. This ensures sufficient drainage and edge effects, improving wet and snow performance. In particular, the first sipes 33A and second sipes 33B with the chamfered portion 34 effectively capture water on the road surface and guide it to the intermediate lug groove 32 while suppressing a decrease in the rigidity of the intermediate land portion 30. In addition, one end of the intermediate lug groove 32 opens to one of the main grooves 10, while the other end terminates within the intermediate land portion 30, which can suppress a decrease in rigidity of the intermediate land portion 30. As a result, it is possible to improve dry performance, wet performance, and snow performance at a high level.

[0034] In the pneumatic tire, as shown in FIG. 3 , the main groove 10 located on the innermost side of the vehicle (i.e., the shoulder main groove 12 on the inner side of the vehicle) has an inner groove wall angle β that is equal to the outer groove wall angle α, while the main grooves 10 other than the innermost main groove 10 (i.e., the pair of center main grooves 11 and the outer shoulder main groove 12 on the vehicle) have an inner groove wall angle β that is smaller than the outer groove wall angle α. Because the innermost main groove 10 is important for drainage and snow removal, making the groove wall angles α, β on both sides of this main groove 10 equal can enhance wet and snow performance. In this case, as a general rule, the inner groove wall angle β and the outer groove wall angle α of the innermost main groove 10 are set smaller than the outer groove wall angles α of the other main grooves 10.

[0035] In the above pneumatic tire, as shown in Figure 2, it is preferable that the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle inner side open into the shoulder main groove 12, and the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle outer side do not communicate with the shoulder main groove 12. By having the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle inner side open into the shoulder main groove 12, drainage and snow removal are ensured, and wet and snow performance can be improved. On the other hand, by having the shoulder lug grooves 42 formed in the shoulder land portion 40 located on the vehicle outer side not communicate with the shoulder main groove 12, dry performance is improved and passing noise caused by the tire can be reduced.

[0036] In the above pneumatic tire, as shown in Fig. 5, the chamfered portion 34 preferably has a curved surface recessed toward the inside of the intermediate land portion 30. This increases the water drainage volume and snow removal volume based on the chamfered portion 34, thereby enhancing the effects of improving wet and snow performance. The radius of curvature R of the curved surface of the chamfered portion 34 is preferably 1.0 mm to 3.0 mm.

[0037] In the above-described pneumatic tire, as shown in Fig. 4, the intermediate land portion 30 preferably has a plurality of third sipes 33C that do not have chamfered portions and extend along extensions of the first sipes 33A and the second sipes 33B. By mixing a plurality of third sipes 33C that do not have chamfered portions with the first sipes 33A and the second sipes 33B that have chamfered portions 34, wet and snow performance can be improved, and the actual contact area of ​​the tread portion 1 can be sufficiently secured, thereby improving dry performance. More specifically, as shown in Fig. 2, it is desirable that the first sipes 33A and the second sipes 33B are alternately arranged along the tire circumferential direction, and the third sipes 33C are arranged along extensions of the first sipes 33A and the second sipes 33B.

[0038] In the pneumatic tire, the intermediate land portion 30 preferably has a plurality of longitudinal sipes 35 extending in the tire circumferential direction, as shown in Fig. 4. By providing the longitudinal sipes 35 in the intermediate land portion 30, the tire circumferential edge can be secured, and cornering performance can be improved, particularly when driving on snow.

[0039] In the above pneumatic tire, as shown in FIG. 4, the plurality of longitudinal sipes 35 branch off from the third sipes 33C and the intermediate lug grooves 32, and the longitudinal sipes 35 branch off from the third sipes 33C are spaced apart from the opening end of the third sipes 33C to the shoulder main groove 12 by a length L of the third sipes 33C. 33C Preferably, the longitudinal sipes 35 branching from the intermediate lug grooves 32 should start at a position between 20% and 80% of the center of the tire, extend circumferentially, and terminate within the intermediate land portion 30, and the longitudinal sipes 35 branching from the intermediate lug grooves 32 should start at a position within 5 mm from the bent corner C of the intermediate lug grooves 32, extend circumferentially, and terminate within the intermediate land portion 30. By specifying the arrangement of the longitudinal sipes 35 in the intermediate land portion 30 in this manner, it is possible to ensure a circumferential edge of the tire without impairing dry performance, and to improve cornering performance, particularly when driving on snow. Here, if the starting points of the longitudinal sipes 35 are outside the above range, the rigidity of the intermediate land portion 30 will decrease, which will be a factor in degrading dry performance.

[0040] In the above pneumatic tire, as shown in FIG. 4, the center land portion 20 has a circumferential narrow groove 21 extending in the tire circumferential direction, a plurality of center lug grooves 22 each having one end opening into the center main groove 11 adjacent to the center land portion 20 and the other end terminating within the center land portion 20, and a plurality of center sipes 23 each having one end opening into the center main groove 11 adjacent to the center land portion 20 and the other end terminating within the center land portion 20, and the inclination angle θ of the opening ends of the center lug grooves 22 and the center sipes 23 with respect to the tire circumferential direction is 22 ,θ 23 are 50° to 80°, and the lengths L of the center lug grooves 22 and the center sipes 23 in the tire width direction are 22 ,L 23are each 40% to 80% of the distance D from the center main groove 11 to the circumferential narrow groove 21, and the circumferential spacing P between the center lug grooves 22 and the center sipes 23 is 5 mm to 20 mm. In this way, the center land portion 20 has, in addition to the circumferential narrow grooves 21, the center lug grooves 22 and the center sipes 23 that do not divide the center land portion 20, thereby improving wet performance without degrading dry performance.

[0041] Here, the inclination angle θ of the center lug groove 22 and the center sipe 23 22 ,θ 23 If the angle is less than 50°, the rigidity of the center land portion 20 decreases, and the effect of improving dry performance decreases. Conversely, if the angle is greater than 80°, the effect of improving wet performance and snow performance decreases. 22 ,L 23 If the distance P is less than 40% of the distance D, the effect of improving wet and snow performance is reduced, and conversely, if it is greater than 80% of the distance D, the rigidity of the center land portion 20 is reduced and the effect of improving dry performance is reduced. Furthermore, if the circumferential distance P between the center lug grooves 22 and the center sipes 23 is less than 5 mm, the rigidity of the center land portion 20 is reduced and the effect of improving dry performance is reduced, and conversely, if it exceeds 20 mm, the effect of improving wet and snow performance is reduced.

[0042] 4, the shoulder land portion 40 preferably has a plurality of shoulder sipes 43 extending in a zigzag pattern in the tire width direction and a plurality of longitudinal sipes 45 extending in the tire circumferential direction from the shoulder sipes 43. By having the shoulder land portion 40 thus have the longitudinal sipes 45 in addition to the zigzag shoulder sipes 43, wet and snow performance can be improved.

[0043] In the above pneumatic tire, as shown in FIG. 4, the intermediate lug groove 32 has a bent shape and has a first groove portion 32A from the opening end P1 to the bending point P2 and a second groove portion 32B from the bending point P2 to the end point P3. The bending point P2 is preferably located at a position of 60% to 90% of the width W of the intermediate lug portion 32 from the opening end P1 of the intermediate lug groove 32. Further, it is preferable that the length La of the first groove portion 32A and the length Lb of the second groove portion 32B satisfy the relationship of 0.3×La < Lb < 0.8La. The length La of the first groove portion 32A is the length from the opening end P1 to the bending point P2 measured along the center line L of the intermediate lug groove 32, and the length Lb of the second groove portion 32B is the length from the bending point P2 to the end point P3 measured along the center line L of the intermediate lug groove 32. Furthermore, the angle θ formed by the first groove portion 32A and the second groove portion 32B at the bending point P2 is preferably in the range of 0° < θ < 90°. The angle θ is the angle formed by the straight line connecting the bending point P2 and the end point P3 of the intermediate lug groove 32 with respect to the straight line connecting the opening end P1 and the bending point P2. By having the intermediate lug groove 32 have a predetermined bent shape in this way, the traction effect during running can be increased, and the dry performance and wet performance can be improved.

[0044] Here, if the distance in the tire width direction from the opening end P1 to the bending point P2 of the intermediate lug groove 32 is less than 60% of the width W of the intermediate lug portion 32, the improvement effects of wet performance and snow performance will decrease. Conversely, if it is greater than 90%, the rigidity of the intermediate lug portion 30 will decrease and the improvement effect of dry performance will decrease. Also, if the ratio Lb / La is 0.3 or less, the improvement effects of wet performance and snow performance will decrease. Conversely, if it is 0.8 or more, the rigidity of the intermediate lug portion 30 will decrease and the improvement effect of dry performance will decrease. Furthermore, if the angle θ formed by the first groove portion 32A and the second groove portion 32B is 90° or more, the effect of increasing the traction effect will decrease.

[0045] In the above-described embodiment, the case of a pneumatic tire has been described, but the present invention is also applicable to a non-pneumatic tire. The non-pneumatic tire has a tread portion that forms an annular shape along the tire circumferential direction, similar to a pneumatic tire. It is only necessary to provide a similar tread pattern for the tread portion.

Example

[0046] In a pneumatic tire (front wheel size: 285 / 40R22, rear wheel size: 315 / 35R22) with a specified mounting direction on a vehicle, the groove wall angle α on the outer side of the vehicle and the groove wall angle β on the inner side of the vehicle of each main groove, the presence or absence of connection of the shoulder lug grooves to the main grooves, the presence or absence of intermediate lug grooves in the intermediate land portion, the presence or absence of first sipes (with chamfers) in the intermediate land portion, the presence or absence of second sipes (with chamfers) in the intermediate land portion, the presence or absence of longitudinal sipes in the intermediate land portion, the presence or absence of curved surfaces in the chamfered portions, the presence or absence of circumferential narrow grooves in the center land portion, the presence or absence of center lug grooves in the center land portion, the presence or absence of center sipes in the center land portion, the presence or absence of third sipes in the intermediate land portion, the presence or absence of shoulder sipes in the shoulder land portion, and the presence or absence of longitudinal sipes in the shoulder land portion were set as shown in Tables 1 and 2. Tires were manufactured as a conventional example, comparative examples 1 to 3, and examples 1 to 8. The intermediate lug groove has a curved shape.

[0047] These test tires were evaluated for steering stability on dry roads, wet roads, and snowy roads using the following test methods. The results are shown in Tables 1 and 2.

[0048] Steering stability on dry roads: Each test tire was mounted on a wheel (front wheel rim size: 22x10J, rear wheel rim size: 22x11.5J) and installed on a test vehicle. After warming up, the tire was inflated to 250kPa / 260kPa (front / rear) and driven on a dry road surface, where a sensory evaluation was carried out by a test driver. The evaluation results were expressed as an index, with the conventional tire being set at 100. The higher the index value, the better the handling stability on dry roads.

[0049] Handling stability on wet roads: Each test tire was mounted on a wheel (front wheel rim size: 22x10J, rear wheel rim size: 22x11.5J) and installed on a test vehicle. After warming up, the tire was inflated to 250kPa / 260kPa (front / rear), and the test driver performed a sensory evaluation while driving on a wet road. The evaluation results were expressed as an index, with the conventional tire being assigned an index value of 100. The higher the index value, the better the handling stability on wet roads.

[0050] Steering stability on snowy roads: Each test tire was mounted on a wheel (front wheel rim size: 22x10J, rear wheel rim size: 22x11.5J) and installed on a test vehicle. After warming up, the tire was inflated to 250kPa / 260kPa (front / rear) and driven on a snowy road. A sensory evaluation was conducted by a test driver. The evaluation results were expressed as an index, with the conventional tire being set at 100. The higher the index value, the better the handling stability on snowy roads.

[0051] [Table 1]

[0052] [Table 2]

[0053] As can be seen from Tables 1 and 2, the tires of Examples 1 to 8 were highly improved in terms of steering stability on dry roads, wet roads, and snowy roads compared to the conventional tires. In contrast, Comparative Examples 1 to 3 did not meet the necessary requirements, and therefore the improvement effect was insufficient. [Explanation of symbols]

[0054] 1 Tread section 2 Sidewall 3 Bead section 10,11,12 Main groove 20 Center Land Section 21 Circumferential thin groove 22 Center lug groove 23 Center sipe 30 Intermediate Land Area 32 Intermediate lug groove 33A First Sipe 33B Second sipe 33C Third sipe 34 Chamfered part 35 Vertical sipes 40 Shoulder Land Section 41 Vertical grooves 42 Shoulder lug groove 43 Shoulder sipes 45 vertical sipes

Claims

1. A tire having a tread portion with a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of land portions defined by the plurality of main grooves, and a mounting direction on a vehicle specified, At least one of the plurality of main grooves has a groove wall angle on an inner side of the vehicle that is smaller than a groove wall angle on an outer side of the vehicle, The plurality of rows of land portions include a center land portion located on the tire equator, a pair of intermediate land portions located on both outer sides of the center land portion, and a pair of shoulder land portions located on the outer sides of each intermediate land portion, Each of the pair of shoulder land portions has a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug groove formed in at least one of the pair of shoulder land portions communicates with a main groove adjacent to the shoulder land portion, Each of the intermediate land portions has a plurality of intermediate lug grooves, one end of which opens into one of the main grooves and the other end of which terminates within the intermediate land portion; a plurality of first sipes, one end of which opens into the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove; and a plurality of second sipes, one end of which opens into the main groove located opposite to the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, each of the first sipes and the second sipes has a chamfered portion on only one of the leading-side edge and trailing-side edge, a tire in which, of the plurality of main grooves, the main groove located furthest on the vehicle's inner side has an equal groove wall angle on the vehicle's inner side and an equal groove wall angle on the vehicle's outer side, and the main grooves other than the main groove located furthest on the vehicle's inner side have a groove wall angle on the vehicle's inner side that is smaller than the groove wall angle on the vehicle's outer side.

2. The tire according to claim 1, characterized in that, of the pair of shoulder land portions, the shoulder lug grooves formed in the shoulder land portion located on the vehicle inner side open to the main groove adjacent to the shoulder land portion, and the shoulder lug grooves formed in the shoulder land portion located on the vehicle outer side do not communicate with the main groove adjacent to the shoulder land portion.

3. The tire according to any one of claims 1 and 2, wherein the chamfered portion has a curved surface recessed toward the inside of the intermediate land portion.

4. The tire according to any one of claims 1 to 3, characterized in that the intermediate land portion has a plurality of third sipes that extend on extension lines of the first sipes and the second sipes and do not have chamfered portions.

5. The tire according to any one of claims 1 to 4, wherein the intermediate land portion has a plurality of longitudinal sipes extending in the tire circumferential direction.

6. The tire according to any one of claims 1 to 3, characterized in that the intermediate land portion has a plurality of third sipes that extend on extension lines of the first sipes and the second sipes and do not have chamfered portions, and a plurality of longitudinal sipes that extend in the tire circumferential direction, the intermediate lug grooves have a curved shape, the intermediate lug grooves have a first groove portion from an opening end to a bending point and a second groove portion from the bending point to an end, the plurality of longitudinal sipes branch off from the third sipes and the intermediate lug grooves, the longitudinal sipes branching off from the third sipes extend in the tire circumferential direction from a position 20% to 80% of the length of the third sipe from the opening end of the third sipe to the main groove and terminate within the intermediate land portion, and the longitudinal sipes branching off from the intermediate lug grooves extend in the tire circumferential direction from a position within 5 mm from the bent corner of the intermediate lug groove and terminate within the intermediate land portion.

7. 7. The tire according to claim 1, wherein the center land portion has a circumferential narrow groove extending in the tire circumferential direction, a plurality of center lug grooves each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, and a plurality of center sipes each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, wherein the inclination angles of the opening ends of the center lug grooves and the center sipes with respect to the tire circumferential direction are 50° to 80°, the lengths of the center lug grooves and the center sipes in the tire width direction are 40% to 80% of the distance from the main groove to the circumferential narrow groove, and the spacing between the center lug grooves and the center sipes in the tire circumferential direction is 5 mm to 20 mm.

8. The tire according to any one of claims 1 to 7, characterized in that the shoulder land portion has a plurality of shoulder sipes extending in a zigzag pattern in the tire width direction and a plurality of longitudinal sipes extending from the shoulder sipes in the tire circumferential direction.

9. The tire according to any one of claims 1 to 8, characterized in that the intermediate lug groove has a curved shape, the intermediate lug groove has a first groove portion from the opening end to a bending point and a second groove portion from the bending point to an end, the bending point is located at a position from the opening end of the intermediate lug groove to 60% to 90% of the width of the intermediate land portion, the length La of the first groove portion and the length Lb of the second groove portion satisfy the relationship 0.3 × La < Lb < 0.8La, and the angle θ formed by the first groove portion and the second groove portion at the bending point is in the range of 0° < θ < 90°.

10. A tire having a tread portion with a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of land portions defined by the plurality of main grooves, and having a specified mounting direction relative to a vehicle, At least one of the plurality of main grooves has a groove wall angle on an inner side of the vehicle that is smaller than a groove wall angle on an outer side of the vehicle, The plurality of rows of land portions include a center land portion located on the tire equator, a pair of intermediate land portions located on both outer sides of the center land portion, and a pair of shoulder land portions located on the outer sides of each intermediate land portion, Each of the pair of shoulder land portions has a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug groove formed in at least one of the pair of shoulder land portions communicates with a main groove adjacent to the shoulder land portion, Each of the intermediate land portions has a plurality of intermediate lug grooves, one end of which opens into one of the main grooves and the other end of which terminates within the intermediate land portion; a plurality of first sipes, one end of which opens into the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove; and a plurality of second sipes, one end of which opens into the main groove located opposite to the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, each of the first sipes and the second sipes has a chamfered portion on only one of the leading-side edge and trailing-side edge, The tire is characterized in that the intermediate land portion has a plurality of longitudinal sipes extending in the tire circumferential direction.

11. A tire having a tread portion with a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of land portions defined by the plurality of main grooves, and a mounting direction relative to a vehicle specified, At least one of the plurality of main grooves has a groove wall angle on an inner side of the vehicle that is smaller than a groove wall angle on an outer side of the vehicle, The plurality of rows of land portions include a center land portion located on the tire equator, a pair of intermediate land portions located on both outer sides of the center land portion, and a pair of shoulder land portions located on the outer sides of each intermediate land portion, Each of the pair of shoulder land portions has a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug groove formed in at least one of the pair of shoulder land portions communicates with a main groove adjacent to the shoulder land portion, Each of the intermediate land portions has a plurality of intermediate lug grooves, one end of which opens into one of the main grooves and the other end of which terminates within the intermediate land portion; a plurality of first sipes, one end of which opens into the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove; and a plurality of second sipes, one end of which opens into the main groove located opposite to the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, each of the first sipes and the second sipes has a chamfered portion on only one of the leading-side edge and trailing-side edge, the intermediate land portion has a plurality of third sipes that extend on extension lines of the first sipes and the second sipes and do not have chamfered portions, and a plurality of longitudinal sipes that extend in the tire circumferential direction, the intermediate lug grooves have a curved shape, the intermediate lug grooves have a first groove portion from the opening end to the bending point and a second groove portion from the bending point to the terminal end, the plurality of longitudinal sipes branch off from the third sipes and the intermediate lug grooves, the longitudinal sipes branching off from the third sipes extend in the tire circumferential direction from a position that is 20% to 80% of the length of the third sipe from the opening end of the third sipe to the main groove and terminate within the intermediate land portion, and the longitudinal sipes branching off from the intermediate lug grooves extend in the tire circumferential direction from a position within 5 mm from the bent corner of the intermediate lug groove and terminate within the intermediate land portion.

12. A tire having a tread portion with a plurality of main grooves extending in the tire circumferential direction and a plurality of rows of land portions defined by the plurality of main grooves, and having a specified mounting direction relative to a vehicle, At least one of the plurality of main grooves has a groove wall angle on an inner side of the vehicle that is smaller than a groove wall angle on an outer side of the vehicle, The plurality of rows of land portions include a center land portion located on the tire equator, a pair of intermediate land portions located on both outer sides of the center land portion, and a pair of shoulder land portions located on the outer sides of each intermediate land portion, Each of the pair of shoulder land portions has a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug groove formed in at least one of the pair of shoulder land portions communicates with a main groove adjacent to the shoulder land portion, Each of the intermediate land portions has a plurality of intermediate lug grooves, one end of which opens into one of the main grooves and the other end of which terminates within the intermediate land portion; a plurality of first sipes, one end of which opens into the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove; and a plurality of second sipes, one end of which opens into the main groove located opposite to the main groove into which the intermediate lug groove opens and the other end of which opens into the intermediate lug groove, each of the first sipes and the second sipes has a chamfered portion on only one of the leading-side edge and trailing-side edge, the center land portion has a circumferential narrow groove extending in the tire circumferential direction, a plurality of center lug grooves each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, and a plurality of center sipes each having one end opening into a main groove adjacent to the center land portion and the other end terminating within the center land portion, wherein the inclination angles of the opening ends of the center lug grooves and the center sipes with respect to the tire circumferential direction are 50° to 80°, the lengths of the center lug grooves and the center sipes in the tire width direction are 40% to 80% of the distance from the main groove to the circumferential narrow groove, and the distance between the center lug grooves and the center sipes in the tire circumferential direction is 5 mm to 20 mm.

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