JP7238488B2 - tire - Google Patents

Description

The present invention relates to a tire including a tread portion.

Conventionally, various proposals have been made for tires including a tread portion. For example, Patent Literature 1 discloses a tire in which crescent-shaped slots are formed in land portions divided between a plurality of main grooves.

JP 2018-95079 A

However, since the crescent-shaped slot convex on one side in the tire axial direction is formed in the land portion, the stiffness is uneven between the inner side and the outer side in the tire axial direction. There is a possibility that it may become a starting point of so-called punching wear, which wears out earlier than the original.

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation as described above, and a main object of the present invention is to provide a tire capable of suppressing punching wear of land portions.

The present invention provides a tire including a tread portion, wherein the tread portion is provided with a plurality of circumferential grooves extending continuously in the tire circumferential direction and a plurality of land portions separated by the circumferential grooves. , at least one of the land portions is provided with a plurality of S-shaped shallow grooves extending in the tire circumferential direction in an S-shape and having both ends terminated within the land portions; One groove bottom is provided with an S-shaped sipe having a groove width smaller than that of the S-shaped shallow groove.

In the tire according to the present invention, the circumferential grooves include a pair of shoulder circumferential grooves disposed on the outer side in the tire axial direction and a pair of crown circumferential grooves disposed between the pair of shoulder circumferential grooves. wherein the land portion includes a middle land portion divided between the shoulder circumferential groove and the crown circumferential groove adjacent in the tire axial direction, and the S-shaped shallow groove is the middle land portion It is desirable to be provided in

In the tire according to the present invention, it is preferable that the middle land portion is provided with a middle shallow groove crossing the middle land portion between a pair of the S-shaped shallow grooves adjacent in the tire circumferential direction.

In the tire according to the present invention, the land portion includes a crown land portion divided between the pair of crown circumferential grooves, and the crown land portion is provided with a crown shallow groove that crosses the crown land portion. and the middle shallow groove and the crown shallow groove have different shapes,
is desirable.

In the tire according to the present invention, it is desirable that the circumferential distance between both ends of the crown shallow groove is 10% to 50% of the pitch length between the crown shallow grooves adjacent in the tire circumferential direction.

In the tire according to the present invention, it is preferable that the circumferential distance between both ends of the middle shallow groove is 25% or less of the pitch length between the middle shallow grooves adjacent in the tire circumferential direction.

In the tire according to the present invention, it is preferable that the S-shaped shallow groove includes a pair of curved portions positioned at both ends and a straight portion connecting the curved portions.

In the tire according to the present invention, it is preferable that the linear portion is inclined at an angle of 15 to 45° with respect to the tire circumferential direction.

In the tire according to the present invention, it is preferable that the groove width of the straight portion is larger than the groove width of the both ends of the S-shaped shallow groove.

In the tire according to the present invention, the length of the S-shaped shallow groove in the tire circumferential direction is 20% to 60% of the pitch length between the S-shaped shallow grooves adjacent in the tire circumferential direction. desirable.

In the tire of the present invention, each of the plurality of shallow S-shaped grooves provided in the land portion meanders alternately inward and outward in the tire axial direction in a series of grooves. Stiffness is uniformed inside and outside the direction. As a result, the force that the rotating land portion receives from the road surface is alternately and uniformly distributed to the inner side and the outer side in the axial direction of the tire, thereby suppressing the punching wear. Further, since the S-shaped sipe is provided in at least one of the groove bottoms of the S-shaped shallow groove, the land portion is appropriately deformed, and the force applied to the tread surface from the road surface is dispersed. ease. This further suppresses punching wear. By means of the S-shaped sipe that communicates with the S-shaped shallow groove and meanders alternately inward and outward in the axial direction of the tire, the force that the tread receives from the road surface is evenly distributed to the axially inward and outward sides of the tire. , the punching wear is further suppressed.

1 is an exploded view of a tread portion showing an embodiment of a tire of the present invention; FIG. It is sectional drawing of the land part cut|disconnected by the cross section containing the S-shaped shallow groove and S-shaped sipe of FIG. FIG. 2 is a front view of a tread portion showing a more specific configuration of the tire of FIG. 1; FIG. 4 is an exploded view of the tread portion of FIG. 3; FIG. 4 is an enlarged development view showing details of a crown land portion and a middle land portion; FIG. 5 is an exploded view of a modification of the tread portion of FIG. 4; FIG. 7 is an exploded view of another modification of the tread portion of FIG. 6;

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a developed view showing an outline of the tread portion 2 of the tire of this embodiment. As shown in FIG. 1, the tire of this embodiment has a tread portion 2. As shown in FIG. The present tire is suitable, for example, as a heavy-duty tire, but its application is not limited to this.

The tread portion 2 is provided with a plurality of circumferential grooves (main grooves) 3 continuously extending in the tire circumferential direction and a plurality of land portions 10 partitioned by the circumferential grooves 3 . The circumferential grooves 3 continuously extend linearly or zigzag in the tire circumferential direction. The circumferential groove 3 of this embodiment is a straight groove extending linearly.

The width W3 of the circumferential groove 3 can be variously determined according to custom. For example, in the tire of this embodiment, the width W3 of the circumferential groove 3 is preferably 3.0% to 8.0% of the tread width TW. The depth of the circumferential groove 3 can be variously determined according to custom. For example, in the tire of this embodiment, the depth of the circumferential grooves 3 is desirably 8.0 to 15.0 mm. However, the dimension of each circumferential groove 3 is not limited to such a range.

The tread contact width TW is defined as the tire axial distance between the tread contact edges TE, TE in the normal state.

Here, the "normal state" is a no-load state in which the tire is mounted on a normal rim (not shown) and filled with a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions of each portion of the tire are values measured in this normal state.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. Then it is "Measuring Rim".

"Normal internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standards on which tires are based. AT VARIOUS COLD INFLATION PRESSURES" is the maximum value, and ETRTO is "INFLATION PRESSURE". If the tire is for passenger cars, the normal internal pressure is, for example, 180 kPa.

The tread edge TE means the outermost tread edge in the axial direction when the tire is in a normal state, a normal load is applied, and the tire is grounded on a flat surface with a camber angle of 0°. In the normal state, the tire axial distance between the tread edges TE, TE is defined as the tread width TW.

"Normal load" is the load defined for each tire by each standard in the standard system including the standards on which the tire is based. LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO. When the tire is for passenger cars, the normal load is, for example, a load corresponding to 88% of the above load.

In FIG. 1, the circumferential grooves 3 may be arranged in any region (that is, position in the tire axial direction) of the tread portion 2 .

The tread portion 2 is divided into a plurality of land portions 10 by a plurality of circumferential grooves 3 . At least one of the land portions 10 is provided with a plurality of S-shaped shallow grooves 6 . The S-shaped shallow grooves 6 are arranged side by side in the tire circumferential direction.

The S-shaped shallow groove 6 extends in the tire circumferential direction in an S-shape, and both ends 6 e terminate within the land portion 10 . "S-shaped" is intended to include an arc-shaped portion having its center on one side in the axial direction of the tire and an arc-shaped portion having its center on the other side in the axial direction of the tire. are arranged in a Z shape, that is, an S-shaped shallow groove 6 reversed symmetrically with respect to the reference line in the tire circumferential direction.

In the tire of the present invention, each of the plurality of shallow S-shaped grooves 6 provided in the land portion 10 meanders alternately inward and outward in the tire axial direction in a series of grooves. Stiffness is uniformed inside and outside the direction. As a result, the force that the tread surface of the rotating land portion 10 receives from the road surface is alternately and uniformly distributed to the inner side and the outer side in the axial direction of the tire, thereby suppressing punching wear.

FIG. 2 shows the land portion 10 cut with a cross section including the S-shaped shallow groove 6 . As shown in FIGS. 1 and 2, at least one groove bottom 6b of the S-shaped shallow groove 6 is provided with an S-shaped sipe 7. As shown in FIGS. Here, the "sipe" is an incision with a width of 2 mm or less (preferably 1.5 mm or less), which closes under ground contact conditions in which a normal load is applied to the tire, that is, under high contact pressure on the tread.

The groove width of the S-shaped sipe 7 is smaller than the groove width of the S-shaped shallow groove 6 . Such an S-shaped sipe 7 moderately deforms the land portion 10 at the contact portion, dispersing and alleviating the force that the tread surface of the land portion 10 receives from the road surface. The S-shaped sipe 7 communicating with the S-shaped shallow groove 6 and meandering alternately inward and outward in the axial direction of the tire causes the tread surface of the land portion 10 to receive force from the road surface alternately inward and outward in the axial direction of the tire. And it is evenly distributed, and punching wear is further suppressed. The S-shaped sipe 7 is arranged at the center of the S-shaped shallow groove 6 in the width direction. This promotes the above effects of the S-shaped sipe 7 .

In this embodiment, the S-shaped sipes 7 are provided on the groove bottoms 6b of all the S-shaped shallow grooves 6. As shown in FIG. This further suppresses punching wear.

The depth Da of the S-shaped shallow groove 6 is preferably 13% to 40% of the depth Db of the S-shaped sipe 7 from the tread surface of the land portion 10 .

When the depth Da is 13% or more of the depth Db, the force that the tread surface of the land portion 10 receives from the road surface is appropriately distributed, and punching wear is suppressed. On the other hand, since the depth Da is 40% or less of the depth Db, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, and the punching wear of the middle land portion 12 is reduced. is suppressed.

From the above point of view, the desirable range of the depth Da is 1.0 to 3.0 mm. A more desirable range of the depth Da is 1.5 to 2.5 mm.

FIG. 3 is a front view showing a more specific configuration of the tire of the present invention, and FIG. 4 is a developed view of its tread portion. The circumferential grooves 3 include a pair of shoulder circumferential grooves 5 arranged on the outer side in the tire axial direction, and a pair of crown circumferential grooves 4 arranged between the pair of shoulder circumferential grooves 5 . The shoulder circumferential groove 5 and the crown circumferential groove 4 are arranged adjacent to each other in the tire axial direction.

The land portion 10 includes a middle land portion 12 partitioned between the shoulder circumferential groove 5 and the crown circumferential groove 4 . The S-shaped shallow groove 6 of this embodiment is provided in the middle land portion 12 . As a result, punching wear of the middle land portion 12 is suppressed.

A plurality of shallow middle grooves 9 are provided in the middle land portion 12 . The middle shallow groove 9 is arranged between a pair of S-shaped shallow grooves 6 adjacent in the tire circumferential direction. The middle shallow groove 9 extends in the tire axial direction, connects the shoulder circumferential groove 5 and the crown circumferential groove 4 , and traverses the middle land portion 12 .

The width of the middle shallow groove 9 is desirably 1.0 to 3.0 mm. Since the width of the middle shallow groove 9 is 1.0 mm or more, the force that the tread surface of the middle land portion 12 receives from the road surface is distributed appropriately, and the punching wear of the middle land portion 12 is suppressed. On the other hand, since the width of the middle shallow groove 9 is 3.0 mm or less, the volume of the rubber forming the middle land portion 12 is easily ensured, and the punching abrasion of the middle land portion 12 is suppressed.

The depth of the middle shallow groove 9 is preferably 1.2-2.0 mm. Since the shallow middle groove 9 has a depth of 1.2 mm or more, the force that the tread surface of the middle land portion 12 receives from the road surface is appropriately distributed, and the punching wear of the middle land portion 12 is suppressed. On the other hand, since the depth of the middle shallow groove 9 is 2.0 mm or less, the volume of the rubber forming the middle land portion 12 is easily ensured, and the punching abrasion of the middle land portion 12 is suppressed.

The middle shallow groove 9 divides the middle land portion 12 into blocks. In this embodiment, one S-shaped shallow groove 6 and one S-shaped sipe 7 are arranged in one block-shaped portion. Each S-shaped shallow groove 6 and each S-shaped sipe 7 meander alternately inward and outward in the tire axial direction in a series of grooves. is uniformized, punching wear is easily suppressed.

The land portion 10 includes a crown land portion 11 located axially inward of the middle land portion 12 . The crown land portion 11 is divided between the pair of crown circumferential grooves 4 .

A crown shallow groove 8 is provided in the crown land portion 11 . The shallow crown groove 8 extends in the tire axial direction, connects the crown circumferential grooves 4 on both sides of the crown land portion 11 , and traverses the crown land portion 11 .

The middle shallow groove 9 and the crown shallow groove 8 have different shapes. More specifically, the middle shallow groove 9 has a portion extending in the shape of an arc, and the crown shallow groove 8 has an S-shaped portion including two arcs. The middle shallow groove 9 and the crown shallow groove 8 facilitate optimization of the rigidity of the middle land portion 12 and the crown land portion 11, thereby easily suppressing punching wear.

FIG. 5 shows details of the crown land portion 11 and the middle land portion 12 . The distance L1 in the tire circumferential direction between both ends of the shallow crown groove 8 is preferably 10% to 50% of the pitch length L2 between the shallow crown grooves 8 adjacent in the tire circumferential direction.

Since the distance L1 is 10% or more of the pitch length L2, the crown land portion 11 is appropriately deformed at the contact portion, and punching wear of the crown land portion 11 is suppressed. On the other hand, since the distance L1 is 50% or less of the pitch length L2, the rigidity of the crown land portion 11 and the volume of the rubber forming the crown land portion 11 are easily ensured, and the punching wear of the crown land portion 11 is reduced. Suppressed.

The distance L3 in the tire circumferential direction between both ends of the middle shallow grooves 9 is preferably 25% or less of the pitch length L4 between the middle shallow grooves 9 adjacent in the tire circumferential direction. Since the distance L3 is 25% or less of the pitch length L4, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, and the punching wear of the middle land portion 12 is suppressed. be.

From the above point of view, the desirable range of the distance L3 is 4.5 to 18.0 mm. A more desirable range of the distance L3 is 9.0 to 13.5 mm.

The distance L3 is preferably smaller than the distance L1. As a result, the S-shaped shallow grooves 6 and the middle shallow grooves 9 can be easily arranged in the middle land portion 12 at appropriate intervals, and the rigidity of the middle land portion 12 and the rubber composing the middle land portion 12 are reduced. The volume is easily secured, and the punching wear of the middle land portion 12 is suppressed.

The length L5 of the S-shaped shallow grooves 6 in the tire circumferential direction is preferably 20% to 60% of the pitch length L6 between the S-shaped shallow grooves 6 adjacent in the tire circumferential direction.

Since the length L5 is 20% or more of the pitch length L6, the force that the tread surface of the middle land portion 12 receives from the road surface is effectively dispersed and alleviated. On the other hand, since the distance L1 is 60% or less of the pitch length L6, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, and the punching wear of the middle land portion 12 is reduced. Suppressed.

From the above viewpoint, the distance L5 is desirably 32.0 mm or less. A more desirable range of the distance L5 is 10.0 to 15.0 mm.

The S-shaped shallow groove 6 includes a pair of curved portions 61 positioned at both ends 6e and a straight portion 62 connecting the curved portions 61. As shown in FIG. Curved portion 61 includes either end 6e. The length of the straight portion 62 is desirably 5.0 to 20.0 mm. With such an S-shaped shallow groove 6, the length L5 of the S-shaped shallow groove 6 in the tire circumferential direction and the amplitude of the S-shaped shallow groove 6 in the tire axial direction can be easily adjusted. is enhanced.

The linear portion 62 is preferably inclined at an angle θ of 45° or less with respect to the tire circumferential direction. A more desirable range of the angle θ is 15 to 30°. By keeping the angle θ within the above range, the rigidity of the middle land portion 12 around the S-shaped shallow groove 6 is optimized, and punching wear is easily suppressed.

The distance L7 between both ends 6e of the S-shaped shallow groove 6 in the direction perpendicular to the straight portion 62 is preferably 80% or less of the length L8 of the middle land portion 12 in the tire axial direction. Since the distance L7 is 80% or less of the length L8, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, so that punching wear of the middle land portion 12 is reduced. Suppressed.

From the above viewpoint, the distance L7 is preferably 24.0 mm or less. A more desirable range of the distance L7 is 12.0 to 15.0 mm.

The groove width of the S-shaped shallow groove 6 at the straight portion 62 is desirably 90% or less of the distance L7. A more desirable groove width at the straight portion 62 is 15% to 40% of the distance L7.

Since the groove width of the S-shaped shallow groove 6 is 15% or more of the distance L7, the force that the tread surface of the middle land portion 12 receives from the road surface is effectively dispersed, and the punching wear of the middle land portion 12 is suppressed. be done. On the other hand, when the groove width is 40% or less of the distance L7, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, so that punching wear of the middle land portion 12 is reduced. is suppressed.

From the above point of view, the desirable range of the groove width of the S-shaped shallow groove 6 is 1.5 to 3.5 mm.

The groove width of the S-shaped shallow groove 6 at the straight portion 62 is larger than the groove width of the S-shaped shallow groove 6 at both ends 6e. As a result, the force that the tread surface of the middle land portion 12 receives from the road surface is effectively dispersed, and the punching wear of the middle land portion 12 is suppressed. In the present embodiment, the groove width of the S-shaped shallow groove 6 gradually decreases toward both ends 6e of the curved portion 61. As shown in FIG. As a result, the rigidity of the middle land portion 12 gradually changes in the tire circumferential direction, so that the generation of starting points of punching wear of the middle land portion 12 is suppressed.

The groove width of the S-shaped shallow groove 6 is equal to the groove width of the S-shaped sipe 7 at both ends 6e. As a result, the rigidity of the middle land portion 12 and the volume of the rubber forming the middle land portion 12 are easily ensured, so that the punching wear of the middle land portion 12 is suppressed.

As shown in FIG. 4 , a shoulder land portion 13 is formed outside the shoulder circumferential groove 5 in the tire axial direction. Land portion 10 includes a shoulder land portion 13 .

The shoulder land portion 13 does not have an S-shaped shallow groove extending in the tire circumferential direction, an S-shaped sipe, or a shallow groove crossing the shoulder land portion 13 . As a result, the rigidity of the shoulder land portion 13 and the volume of the rubber forming the shoulder land portion 13 are easily ensured, so that so-called shoulder drop wear is suppressed.

In the tread portion 2 of the present embodiment, an auxiliary groove 20 extending in the tire circumferential direction is formed outside the shoulder land portion 13 in the tire axial direction. The auxiliary groove 20 further suppresses the above-mentioned shoulder drop wear. Note that the auxiliary groove 20 is not an essential component and may be omitted.

Lateral sipes 14 extending in the tire axial direction are formed at both axial end portions of the crown land portion 11 . The lateral sipe 14 extends inwardly of the crown land portion 11 from the crown circumferential groove 4 and terminates within the crown land portion 11 .

The lateral sipes 14 effectively disperse the force that the tread receives from the road surface at both ends of the crown land portion 11 , thereby suppressing punching wear of the crown land portion 11 . A portion of the lateral sipe 14 is provided at the groove bottom of the shallow crown groove 8 . As a result, at both ends of the crown land portion 11, the force that the tread surface receives from the road surface is dispersed more effectively.

Lateral sipes 15 extending in the tire axial direction are formed at both ends of the middle land portion 12 in the tire axial direction. The lateral sipes 15 extend inwardly of the middle land portion 12 from the crown circumferential groove 4 or the shoulder circumferential groove 5 and terminate within the middle land portion 12 .

The lateral sipes 15 effectively disperse the force that the tread surface receives from the road surface at both ends of the middle land portion 12 , thereby suppressing punching wear of the middle land portion 12 . A part of the lateral sipe 15 is provided at the groove bottom of the middle shallow groove 9 . As a result, at both ends of the middle land portion 12, the force that the tread surface receives from the road surface is dispersed more effectively.

A lateral sipe 16 extending in the tire axial direction is formed at the inner end portion of the shoulder land portion 13 in the tire axial direction. The lateral sipe 16 extends inwardly of the shoulder land portion 13 from the shoulder circumferential groove 5 and terminates within the shoulder land portion 13 .

The lateral sipes 16 effectively disperse the force that the tread surface receives from the road surface at the inner end portion of the shoulder land portion 13 . As a result, uneven wear of the shoulder land portion 13 is suppressed in combination with the effect of the auxiliary grooves.

Note that the lateral sipes 14, 15, 16 are not essential components and may be omitted.

Although the tire of the present invention has been described in detail above, the present invention is not limited to the above-described specific embodiments and can be implemented in various modifications. For example, in the tire of the present invention, the tread portion 2 can be modified as follows.

6 and 7 are developed views of tread portions 2A and 2B which are modifications of the tread portion 2 of FIG. Of the tread portions 2A and 2B, the configuration of the tread portion 2 described above can be employed for portions that are not described below.

The tread portion 2A differs from the tread portion 2 described above in that an S-shaped shallow groove 6 and an S-shaped sipe 7 are formed in the crown land portion 11 . The S-shaped shallow grooves 6 of the crown land portion 11 are arranged between adjacent crown shallow grooves 8 in the tire circumferential direction. The S-shaped shallow grooves 6 and the S-shaped sipes 7 of the crown land portion 11 effectively disperse the force that the tread surface of the crown land portion 11 receives from the road surface, thereby suppressing punching wear of the crown land portion 11 .

The tread portion 2B differs from the above-described tread portion 2A in that a circumferential sipe 17 is formed in the crown land portion 11 . The circumferential sipes 17 are arranged between the crown shallow grooves 8 adjacent to each other in the tire circumferential direction. The circumferential sipes 17 disperse the force that the tread surface of the crown land portion 11 receives from the road surface, thereby suppressing punching wear of the crown land portion 11 .

Moreover, in the tread portions 2, 2A, and 2B, the S-shaped shallow grooves 6 and the S-shaped sipes 7 may be provided in the shoulder land portions 13.

A pneumatic tire of size: 295/75R22.5 having the basic pattern shown in FIG. The test method is as follows.

<Uneven wear resistance performance>
A test tire mounted on a 22.5 x 8.25 rim was mounted on eight wheels of a two-axle trailer towed by a 2DD vehicle under the condition of an internal pressure of 830 kPa. After running 20,000 km, the amount of wear was measured at 6 points on the circumference of each land portion, and the average value was calculated for each land portion. The results are expressed as an index with Comparative Example 1 being 100. The larger the numerical value, the smaller the difference in the amount of wear between the land portions and the better the uneven wear resistance.

As is clear from Table 1, it was confirmed that the tire of the example had significantly improved resistance to uneven wear compared to the comparative example.

2 Tread portion 2A Tread portion 2B Tread portion 3 Circumferential groove 4 Crown circumferential groove 5 Shoulder circumferential groove 6 S-shaped shallow groove 6b Groove bottom 6e Both ends 7 S-shaped sipe 8 Crown shallow groove 9 Middle shallow groove 10 Land portion 11 Crown land portion 12 Middle land portion 61 Curved portion 62 Straight portion L1 Distance L2 Length L3 Distance L4 Length L5 Distance L6 Length L7 Distance

Claims (9)

A tire including a tread portion,
The tread portion is provided with a plurality of circumferential grooves continuously extending in the tire circumferential direction and a plurality of land portions separated by the circumferential grooves,
At least one of the land portions is provided with a plurality of S-shaped shallow grooves extending in the tire circumferential direction in an S shape and having both ends terminated within the land portions,
At least one groove bottom of the S-shaped shallow groove is provided with an S-shaped sipe having a groove width smaller than that of the S-shaped shallow groove ,
The circumferential grooves include a pair of shoulder circumferential grooves disposed axially outward of the tire, and a pair of crown circumferential grooves disposed between the pair of shoulder circumferential grooves,
the land portion includes a middle land portion partitioned between the shoulder circumferential groove and the crown circumferential groove adjacent in the tire axial direction;
The S-shaped shallow groove is provided in the middle land portion,
tire. A tire including a tread portion,
The tread portion is provided with a plurality of circumferential grooves continuously extending in the tire circumferential direction and a plurality of land portions separated by the circumferential grooves,
At least one of the land portions is provided with a plurality of S-shaped shallow grooves extending in the tire circumferential direction in an S shape and having both ends terminated within the land portions,
At least one groove bottom of the S-shaped shallow groove is provided with an S-shaped sipe having a groove width smaller than that of the S-shaped shallow groove,
The S-shaped shallow groove includes a pair of curved portions located at both ends and a straight portion connecting the curved portions,
tire. 2. The tire according to claim 1 , wherein the middle land portion is provided with a middle shallow groove crossing the middle land portion between a pair of the S-shaped shallow grooves adjacent in the tire circumferential direction. the land portion includes a crown land portion partitioned between a pair of the crown circumferential grooves;
The crown land portion is provided with a crown shallow groove that crosses the crown land portion,
The tire according to claim 3, wherein the middle shallow groove and the crown shallow groove have different shapes. The tire according to claim 4, wherein the distance in the tire circumferential direction between both ends of the crown shallow groove is 10% to 50% of the pitch length between the crown shallow grooves adjacent in the tire circumferential direction. The tire according to any one of claims 3 to 5, wherein the distance in the tire circumferential direction between both ends of said middle shallow groove is 25% or less of the pitch length between said middle shallow grooves adjacent in the tire circumferential direction. The tire according to claim 2, wherein the straight portion is inclined at an angle of 15 to 45° with respect to the tire circumferential direction . The tire according to claim 2 or 7, wherein the groove width of the straight portion is larger than the groove width of the both ends of the S-shaped shallow groove . 9. The length of the S-shaped shallow groove in the tire circumferential direction is 20% to 60% of the pitch length between the S-shaped shallow grooves adjacent in the tire circumferential direction. Tires as stated.

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