tire

Abstract

To provide a tire which has satisfactory drainage performance even upon wear progress of tire.SOLUTION: A tire includes at least one of shoulder groove 4 on shoulder land parts 3a, 3b divided by a circumferential direction main groove 2a arranged on the tire width direction outermost side and a tread end TE, the shoulder groove 4 has on the groove bottom side a widened portion 4a in which a groove width becomes larger than the tread surface 1 side, the shoulder groove 4 is extended along a tire width direction on the tread surface 1, and the largest width portion Pw in a tire radial direction of the widened portion 4a is extended at an inclination angle of 25° or more for the tire width direction in the plane sight of the tread surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART Tires have been disclosed that have sipes with widened bottoms in order to suppress a decrease in drainage performance due to the progression of tire wear (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-111421 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the prior art, there is room for further improvement in drainage performance as tire wear progresses.

[0005] Therefore, an object of the present invention is to provide a tire that has sufficient drainage even as the tire wear progresses. [Means for solving the problem]

[0006] The gist of the present invention is as follows. The tread surface has a plurality of circumferential main grooves extending in the tire circumferential direction, At least one shoulder groove is provided in a shoulder land portion defined by the circumferential main groove arranged on the outermost side in the tire width direction and a tread edge, The shoulder groove has a widened portion on the groove bottom side, the widened portion having a groove width larger than that on the tread surface side, The shoulder groove extends along the tire width direction on the tread surface, A tire characterized in that the widest portion in the tire radial direction of the widened portion extends at an inclination angle of 25° or more with respect to the tire width direction when viewed in a plan view of the tread surface. The tire of the present invention can have sufficient drainage even when the tire is worn.

[0007] In the tire of the present invention, the groove width of the shoulder groove on the tread surface is preferably less than 1.5 mm. This effectively maintains the rigidity of the tire when it is new.

[0008] In the tire of the present invention, the extension length of the shoulder groove on the tread surface is preferably 25% or more of the tire ground contact width. This effectively ensures sufficient drainage.

[0009] In the tire of the present invention, it is preferable that 3 to 10 of the shoulder grooves are arranged in the shoulder land portion within the ground contact patch of the tire. This effectively ensures sufficient drainage, and also effectively ensures the rigidity of the land portion where the shoulder grooves are provided.

[0010] In the tire of the present invention, the shoulder land portion is partitioned into a plurality of block land portions by a plurality of widthwise grooves extending in the tire width direction and communicating with the tread edge and the circumferential main groove, It is preferable that 2 to 10 of the block land portions are arranged within the contact patch of the tire. This makes it possible to more effectively ensure the drainage performance of the tire and to maintain sufficient rigidity of the block land portions.

[0011] In the tire of the present invention, it is preferable that one to three of the shoulder grooves are arranged in each of the block land portions. This effectively ensures sufficient drainage when the tire wears, and also maintains sufficient rigidity of the block land portion where the shoulder grooves are arranged. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a tire that has sufficient drainage properties even as the tire wear progresses. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram schematically showing a contact patch of a tire according to a first embodiment of the present invention as viewed in the axial direction of the tire. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 10 is a schematic perspective view for explaining the shape of a shoulder groove. [Figure 4] FIG. 4 is a diagram schematically showing a contact patch of a tire according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The tire according to the present invention can be used for any type of tire, but is preferably used for a passenger vehicle tire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a tire according to the present invention will be described with reference to the drawings. The same reference numerals are used to designate the same components in the various drawings.

[0015] [First embodiment] Fig. 1 is a diagram schematically showing the contact patch of a tire 10 according to a first embodiment of the present invention as viewed in the axial direction of the tire. In Fig. 1, grooves in a plan view of a tread surface 1 as tire wear progresses are also shown by dotted lines. In Fig. 1, the outer contour of the contact patch as tire wear progresses is also shown by a dotted line C1.

[0016] In this specification, the term "tread surface (1)" refers to the outer peripheral surface of the tire that comes into contact with the road surface when the tire is mounted on a rim and inflated to a predetermined internal pressure and rolls under maximum load. In this specification, the term "tread edge (TE)" means the edge of the tread surface (1) in the tire width direction. Here, "rim" refers to the standard rim (Measuring Rim in the ETRTO STANDARDS MANUAL, Design Rim in the TRA YEAR BOOK) for the applicable size that is described or will be described in the future, as an industrial standard in effect in the region where the tire is produced and used, such as the JATMA YEAR BOOK of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the European Tyre and Rim Technical Organization (ETRTO) in Europe, or the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the United States. (In other words, the above "rim" includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of a "size to be described in the future" is the size listed as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO STANDARDS MANUAL.) However, in the case of a size not described in the above industrial standards, it refers to a rim with a width that corresponds to the bead width of the tire. Furthermore, "prescribed internal pressure" refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity of a single wheel for the applicable size and ply rating, as stated in the above-mentioned JATMA YEAR BOOK, etc., and in the case of sizes not stated in the above-mentioned industry standards, it refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity specified for each vehicle on which the tire is fitted. "Maximum load" refers to the load corresponding to the maximum load capacity. The air referred to here can be replaced with an inert gas such as nitrogen gas or the like.

[0017] In this specification, unless otherwise specified, the dimensions of each element such as a groove or land portion, the contact patch width (TW), etc. are measured in the "reference state" described below. In this specification, the "standard state" refers to a state in which a tire is mounted on a rim, inflated to the above-mentioned predetermined internal pressure, and no load is applied.

[0018] In this specification, "groove width" refers to the distance between a pair of opposing groove walls measured perpendicular to the groove extension direction. Also, in this specification, "groove depth" refers to the distance from the tread surface to the groove bottom position in a direction perpendicular to the tread surface in a cross section along the groove width direction.

[0019] In addition, in this specification, "contact surface" means the outer peripheral surface of the tire that comes into contact with the road surface when the tire, which has been mounted on a rim and inflated to a predetermined internal pressure, is placed in contact with the road surface under maximum load.

[0020] In this specification, the "tire circumferential direction" is also referred to as the "tire circumferential direction CD1" or the "tire circumferential direction CD2," and the "tire width direction" is also referred to as the "tire width direction WD." In each drawing, the tire circumferential direction (CD) is indicated by the CD1 and CD2 arrows, and the tire width direction (WD) is indicated by the WD arrow.

[0021] As shown in Fig. 1, a tire 10 according to a first embodiment of the present invention has a plurality of circumferential main grooves 2 extending in the tire circumferential direction on the tread surface. In this embodiment, a pair of circumferential main grooves 2a are arranged on the outermost sides in the tire width direction, and a circumferential main groove 2b extends along the tire equatorial plane CL. In the example shown in Fig. 1, the number of circumferential main grooves 2 is three, but it may also be two or four or more.

[0022] In a plan view of the tread surface 1 of the tire 10 of this embodiment, the circumferential main grooves 2a and 2b do not extend at an angle relative to the tire circumferential direction, but at least one circumferential main groove 2 may extend at an angle relative to the tire circumferential direction, for example, at an angle of 5° or less relative to the tire circumferential direction. Furthermore, each circumferential main groove 2 may extend linearly along the tire circumferential direction as shown in Fig. 1, or may extend circumferentially in a zigzag or wavy pattern, etc.

[0023] Although the groove width of the circumferential main grooves 2a and 2b is not particularly limited, from the viewpoint of drainage performance and driving stability, it is preferable that the pair of opposing groove wall surfaces do not come into contact with each other immediately after the load is applied when the tire is mounted on a rim, inflated to a predetermined internal pressure, and subjected to a maximum load. More specifically, it is preferable that the groove width in the standard state is more than 1.5 mm. The groove depth of the circumferential main grooves 2a and 2b is not particularly limited, but from the viewpoint of sufficient drainage and maintaining the rigidity of the tire, it is preferable that the groove depth be, for example, 3 mm or more and 20 mm or less.

[0024] In the tread surface 1 of the tire 10 of this embodiment, shoulder land portions 3a and 3b are defined by a pair of circumferential main grooves 2a arranged on the outermost sides in the tire width direction and the tread edge TE, and center land portions 3c and 3d are defined by the circumferential main groove 2b and the pair of circumferential main grooves 2a. In the tire 10 of this embodiment, the shoulder land portions 3a and 3b and the center land portions 3c and 3d are rib-shaped land portions that are not divided in the tire circumferential direction, but they can also be block-shaped land portions that are divided by widthwise grooves.

[0025] In the example shown in FIG. 1, the central land portions 3c and 3d do not have grooves or the like extending in the tire width direction, but grooves or the like extending in the tire width direction may be provided as appropriate.

[0026] In the tire 10 of this embodiment, each of the shoulder land portions 3a and 3b is provided with at least one shoulder groove 4. In Fig. 1, two shoulder grooves 4 are provided in each of the shoulder land portions 3a and 3b on the ground contact surface, but the number and arrangement of the shoulder grooves 4 are not particularly limited. For example, the shoulder groove 4 may be provided in only one of the shoulder land portions 3a and 3b.

[0027] Hereinafter, the shoulder groove 4 will be described in further detail with reference to FIGS. 1, 2 and 3, taking the shoulder groove 4 provided in the shoulder land portion 3a as a typical example. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a schematic perspective view for explaining the shape of the shoulder groove.

[0028] In this embodiment, the shoulder groove 4 extends along the tire width direction WD on the tread surface 1. Here, extending "along the tire width direction" means that the shoulder groove 4 is parallel to the tire width direction WD in a plan view of the tire, or that the shoulder groove 4 extends at an inclination angle of 5° or less with respect to the tire width direction. In addition, the shoulder groove 4 may extend linearly in the tire width direction as shown in FIG. 1, or may extend in a zigzag or wavy pattern in the tire width direction. Here, "zigzag in the tire width direction" means that each linear portion constituting the zigzag shape extends along the tire width direction.

[0029] In the example shown in FIG. 1, the shoulder groove 4 opens to the tread edge TE of the shoulder land portion 3a, extends toward the circumferential main groove 2a, and terminates on the shoulder land portion 3a. However, the configuration of the shoulder groove 4 is not limited to this, and for example, the shoulder groove 4 may open to both the tread edge TE and the circumferential main groove 2a. The groove width of the shoulder groove 4 on the tread surface 1 is not particularly limited.

[0030] The shoulder groove 4 has a widened portion whose groove width is larger than that on the groove bottom side of the tread surface 1. In this embodiment, as shown in Fig. 2, a first widened portion 4a whose groove width is larger than that on the tread surface 1 side is provided on the groove bottom 43 side (downward in the illustrated example) and a second widened portion 4b whose groove width is larger than that of the first widened portion 4a is provided on the groove bottom side of the first widened portion 4a, but the shapes of the first widened portions 4a and 4b are not particularly limited. For example, as shown in Figure 2, the first widening portion 4a may have a shape in which the groove width increases stepwise from the tread surface 1 toward the second widening portion 4b, or the groove 4 may have a constant groove width without widening from the tread surface 1 to the second widening portion 4b. 2, the groove width may increase stepwise from the tread surface 1 side toward the groove bottom 43 side in a cross-sectional view, with the maximum width portion near the groove bottom 43. The shape of the second widened portion 4b is not particularly limited either, and the second widened portion 4b may have a constant groove width from the first widened portion 4a side to the groove bottom 43, such as by making the cross-sectional shape of the second widened portion 4b rectangular. The second widened portion 4b may have a maximum width portion midway from the first widened portion 4a side to the groove bottom 43, such as by making the cross-sectional shape of the second widened portion 4b circular or elliptical.

[0031] As shown in FIG. 2, the boundaries between the groove walls 41 and 42 and the groove bottom 43 of the shoulder groove 4 may be arcuate side walls and groove bottoms having any radius of curvature, or the groove walls 41 and 42 and the groove bottom 43 may be linear in a cross section perpendicular to the extension direction of the groove.

[0032] As described above, in the tire 10 of the first embodiment, the shoulder grooves 4 extend along the tire width direction WD on the tread surface 1, as shown in Fig. 1. In addition, as shown by dotted lines in Fig. 1, the maximum width portion Pw of the second widened portion 4b of the shoulder groove 4 in the tire radial direction is configured so that the inclination angle θ1 with respect to the tire width direction WD is 25° or more in a plan view of the tread surface 1 (i.e., extends at an inclination angle of 25° or more with respect to the tire width direction WD). Here, the maximum width portion (Pw) of the second widened portion 4b means the portion where the distance between a pair of opposing groove wall surfaces is maximum when measured perpendicular to the extension direction of the second widened portion 4b of the shoulder groove 4 in the standard state. In addition, the inclination angle θ1 of the maximum width portion Pw in a plan view of the tread surface 1 means the inclination angle with respect to the tire width direction WD of a line segment connecting one end of the shoulder groove 4 (in the example of FIG. 1, one end in the tire width direction) and the other end of the shoulder groove 4 (in the example of FIG. 1, the other end in the tire width direction) (in the example of FIG. 1, the line segment connecting the groove width direction center of one end of the shoulder groove 4 and the groove width direction center of the other end of the shoulder groove 4).

[0033] As shown in Fig. 3, in the tire 10 of this embodiment, the shoulder grooves 4 extend in the tire width direction WD on the tread surface 1, and the inclination angle with respect to the tire width direction WD changes continuously from the tread surface 1 toward the groove bottom, so that the inclination angle θ1 is 25° or more. The shoulder grooves 4 are not limited to this configuration, and may be configured so that the portion from the tread surface 1 to the second widened portion 4b extends in the tire width direction WD, and the second widened portion 4b extends at a constant inclination angle θ1. Alternatively, the shoulder grooves 4 may be configured so that the angle changes stepwise from the tread surface 1 toward the groove bottom.

[0034] The effects of the tire configuration of the first embodiment will be described. According to the tire 10 of this embodiment, by arranging shoulder grooves 4 extending along the tire width direction WD on the tread surface 1 in the shoulder land portions 3a and 3b arranged on the outermost sides in the tire width direction, drainage performance can be ensured. Because the shoulder grooves 4 extend along the tire width direction WD, when the tire 10 travels straight, they come into contact with the ground along the contour line of the leading side of the contact patch, and uneven wear and noise generation at the ends of the shoulder grooves 4 can be suppressed. In addition, the shoulder groove 4 has a widened portion (in this embodiment, a first widened portion 4a and a second widened portion 4b) on the groove bottom side where the groove width is larger than that on the tread surface 1 side, so that sufficient drainage can be ensured even when the tire wears. Furthermore, the shoulder groove 4 is inclined by 25° or more with respect to the tire width direction WD as tire wear progresses. As tire wear progresses, the outer contour of the contact patch changes from the state before wear progresses, as illustrated by the dotted line C1 in FIG. 1 . The drainage performance of a groove tends to improve as the groove extends in a direction perpendicular to the outer contour of the contact patch at a position closer to the leading edge of the tire. Therefore, in this embodiment, as shown in FIG. 1 , before tire wear progresses, the shoulder groove 4 extends along the tire width direction, and after tire wear progresses, the shoulder groove 4 (in this embodiment, the second widened portion 4b) extends at an inclination of 25° or more with respect to the tire width direction. As a result, after tire wear progresses, when the shoulder groove 4 approaches the leading edge of the tire as the tire rotates, drainage from the inner side in the tire width direction toward the tread edge TE is promoted at the timing when the shoulder groove 4 becomes approximately perpendicular to the outer contour of the contact patch after wear progresses. Furthermore, by providing the shoulder grooves 4 in the shoulder land portion, drainage toward the tread end TE is more easily promoted than when the shoulder grooves 4 are provided in the central land portion, and sufficient drainage can be ensured even when the tire wears.

[0035] Preferred configurations and modifications of the tire of the first embodiment will be described below.

[0036] The groove depth d1 of the shoulder groove 4 is not particularly limited, but from the viewpoint of ensuring sufficient drainage and maintaining the rigidity of the tire, it is preferable that the depth be approximately the same as that of the circumferential main grooves 2a and 2b. More specifically, the groove depth d1 is preferably, for example, 3 mm or more and 20 mm or less, and more preferably 5 mm or more and 10 mm or less.

[0037] The length d2 of the second widened portion 4b of the shoulder groove 4 in the groove depth direction is not particularly limited, but from the viewpoint of effectively ensuring sufficient drainage while maintaining sufficient rigidity of the land portion where the shoulder groove 4 is provided, the length d2 is preferably 30% to 70% of the depth d1 of the entire shoulder groove 4. More preferably, the length d2 is 40% to 60% of the groove depth d1.

[0038] The groove width w1 of the shoulder groove 4 on the tread surface 1 is not particularly limited, but is preferably less than 1.5 mm in the standard state from the viewpoint of effectively maintaining the rigidity of the new tire. From the viewpoint of ensuring sufficient drainage of the shoulder groove 4, it is preferably 1 mm or more.

[0039] The groove width w2 at the maximum width portion Pw of the second widened portion 4b of the shoulder groove 4 is not particularly limited either, but from the viewpoint of sufficient drainage when tire wear progresses, the groove width w2 can be set to, for example, 1.5 mm or more, and from the viewpoint of maintaining sufficient rigidity of the land portion provided with the shoulder groove 4, it is preferable to set it to, for example, 4 mm or less. More preferably, from the viewpoint of achieving both sufficient drainage when tire wear progresses and maintaining rigidity of the land portion, the groove width w2 is set to 2.0 mm or more and less than 3.5 mm.

[0040] Although there are no particular limitations on the extension length L1 of the shoulder groove 4 on the tread surface 1, it is preferably 25% or more of the tire contact width TW. By making the extension length L1 25% or more of the tire contact width TW, water from the road surface can be sufficiently taken into the groove, effectively ensuring sufficient drainage.

[0041] Although there is no particular limitation on the number of shoulder grooves 4, from the viewpoint of ensuring sufficient drainage, it is preferable that two or more grooves are arranged in each of the shoulder land portions 3a and 3b in the contact patch of the tire. More preferably, from the viewpoint of ensuring sufficient drainage and rigidity of the land portions where the shoulder grooves 4 are provided, it is preferable that three to ten grooves are arranged in each of the shoulder land portions 3a and 3b in the contact patch. Here, "located within the ground contact surface" means that the shoulder groove 4 is located within the ground contact surface if even a part of the shoulder groove 4 is located within the ground contact surface.

[0042] The inclination angle (acute angle) θ1 of the maximum width portion Pw in the tire radial direction of the second widened portion 4b of the shoulder groove 4 with respect to the tire width direction WD in a plan view of the tread surface 1 is not particularly limited as long as it is 25° or more, but is preferably 50° or less in order to effectively ensure sufficient drainage while sufficiently maintaining the tire's circumferential traction performance. More preferably, the inclination angle θ1 of the second widened portion 4b is 28° or more and 45° or less.

[0043] Although the rotation direction of the tire 10 is not particularly limited, it is preferable that the tire 10 be mounted so as to rotate in the tire circumferential direction CD1 in FIG. 1 , or that the tire 10 be mounted so as to rotate in that direction, in order to more effectively promote drainage from the inner end of the shoulder groove 4 in the tire width direction toward the tread edge TE, particularly as wear progresses. In the example of FIG. 1 , this means that the tire is rotated so that the maximum width portion Pw of the second widened portion 4b of the shoulder groove 4 slopes from the leading edge to the trailing edge of the tire as it moves from the inner side to the outer side in the tire width direction after tire wear progresses. By mounting the tire in this manner, after tire wear progresses, drainage from the leading edge to the trailing edge of the tire's contact patch by the second widened portion 4b of the shoulder groove 4 is more effectively promoted. Furthermore, after tire wear progresses, the groove extends at an angle from the leading edge of the tire's contact patch toward the water drainage direction, thereby achieving sufficient wet grip with the road surface.

[0044] [Second embodiment] Next, a tire according to another embodiment (second embodiment) of the present invention will be described with reference to Fig. 4. A tire 20 of the second embodiment has the same configuration as the tire of the first embodiment except for the configuration of the shoulder land portion, and the same components as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

[0045] Fig. 4 is a diagram schematically showing the ground contact patch of a tire 20 according to a second embodiment of the present invention. In Fig. 4, grooves in a plan view of the tread surface 11 as the tire wear progresses are also shown by dotted lines.

[0046] In the tread surface 11 of the tire 20 of this embodiment, shoulder land portions 30a and 30b are defined by a pair of circumferential main grooves 2a arranged at the outermost sides in the tire width direction and the tread edge TE, and center land portions 3c and 3d are defined by the circumferential main groove 2b and the pair of circumferential main grooves 2a.

[0047] The shoulder land portions 30a and 30b are divided into a plurality of block land portions 301a and 301b by a plurality of widthwise grooves 50 (in this embodiment, two in each of the shoulder land portions 30a and 30b within the contact patch) that extend in the tire width direction and communicate with the tread edge TE and the circumferential main groove 2a (in this embodiment, one block land portion 301a and one block land portion 301b are arranged in their entirety within the contact patch, and two block land portions 301a and two block land portions 301b are arranged in their partial contact patch).

[0048] The width direction grooves 50 may be parallel to the tire width direction WD in a plan view of the tire, or may extend at an inclination angle of 45° or less with respect to the tire width direction WD. The width direction grooves 50 may extend linearly in the tire width direction as shown in Fig. 4, or may extend in a zigzag or wavy pattern in the tire width direction.

[0049] In the tire 20 of this embodiment, the number of block land portions arranged in the contact patch is not particularly limited, but it is preferable that 2 to 10 block land portions 301a and 301b are arranged in the contact patch. By arranging two or more block land portions 301a and 301b in the contact patch, the drainage performance of the tire can be more effectively ensured, and by limiting the number of each to 10 or less, sufficient rigidity of the block land portions can be maintained. Here, "disposed within the ground surface" means that even if only a part of the block land portions 301a and 301b is located within the ground surface, the block land portions are considered to be located within the ground surface.

[0050] In the tire 20 of this embodiment, from the viewpoint of effectively ensuring sufficient drainage when the tire wear progresses, it is preferable that one or more shoulder grooves 4 are arranged in each of the block land portions 301a and 301b. Also, from the viewpoint of sufficiently maintaining the rigidity of the block land portion in which the shoulder grooves 4 are arranged, it is preferable that the number of shoulder grooves 4 arranged in each of the block land portions 301a and 301b is three or less. [Industrial Applicability]

[0051] The tire according to the present invention can be used for any type of tire, but is preferably used for a passenger vehicle tire. [Explanation of symbols]

[0052] 1, 11: tread surface, 2, 2a, 2b: circumferential main groove, 3a, 3b, 30a, 30b: shoulder land portion, 3c, 3d: center land portion, 4: shoulder groove, 4a: widened portion, 4b: narrow groove portion, 10, 20: tire, 41, 42: groove wall, 43: groove bottom, 50: widthwise groove, 301a, 301b: block land portion, Pw: maximum width portion, WD: tire width direction, CD1, CD2: tire circumferential direction, TE: tread edge

Claims

1. The tread surface has a plurality of circumferential main grooves extending in the tire circumferential direction, At least one shoulder groove is provided in a shoulder land portion defined by the circumferential main groove arranged on the outermost side in the tire width direction and a tread edge, The shoulder groove has a widened portion on the groove bottom side, the widened portion having a groove width larger than that on the tread surface side, The shoulder groove extends along the tire width direction on the tread surface, a maximum width portion in the tire radial direction of the widened portion extends at an inclination angle of 25° or more with respect to the tire width direction in a plan view of the tread surface, The tire, wherein the extension length of the shoulder groove on the tread surface is 25% or more of the tire ground contact width.

2. The tire according to claim 1 , wherein the shoulder groove has a groove width at the tread surface of less than 1.5 mm.

3. The tire according to claim 1 or 2, wherein 3 to 10 of the shoulder grooves are arranged in the shoulder land portion within the contact patch of the tire.

4. the shoulder land portion is partitioned into a plurality of block land portions by a plurality of widthwise grooves extending in the tire width direction and communicating with the tread edge and the circumferential main groove, The tire according to any one of claims 1 to 3, wherein 2 to 10 of the block land portions are arranged in the contact patch of the tire.

5. The tire according to claim 4, wherein one to three of the shoulder grooves are arranged in each of the block land portions.

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