JP2014213682A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rigidity of a land in a tire axial direction while ensuring drainage performance.SOLUTION: A tire 10 (an example of a pneumatic tire) comprises: a center circumferential groove 14 (an example of circumferential grooves) provided on a tread 12 and extending in a tire circumferential direction; a plurality of bottom grooves 40 provided on a bottom surface 14A of the center circumferential groove 14 in an extension direction of the center circumferential groove 14 at intervals, extending along the center circumferential groove 14, and having both end portions 40B bent in a direction crossing the extension direction of the center circumferential groove 14; and a coupling portion 42 provided in a longitudinal intermediate portion 40D of each bottom groove 40 and coupling groove walls 40A facing each other.

Description

  The present invention relates to a pneumatic tire.

  There is a tire in which a groove in a groove extending in the tire circumferential direction is formed on the bottom surface of a shoulder circumferential groove extending in the tire circumferential direction in order to improve drainage performance (for example, Patent Document 1).

International Publication No. 2011/102457 Pamphlet

By the way, in the said tire, since the groove | channel in a groove | channel is formed in the bottom face of a circumferential groove | channel, there exists a tendency for the rigidity of the tire axial direction in the position corresponding to the groove | channel groove | channel of the land part adjacent to a circumferential groove | channel to fall. For this reason, the groove width and groove depth of the groove in the groove are limited to ensure the rigidity of the land portion in the tire axial direction.
However, if the groove width and the groove depth of the groove in the groove are limited, it is difficult to ensure sufficient drainage performance.
This invention makes it a subject to improve the rigidity of the tire axial direction of a land part, ensuring drainage performance.

The pneumatic tire according to claim 1 of the present invention is provided in the tread, and has a circumferential groove extending along a tire circumferential direction, and a space in a direction in which the circumferential groove extends on a bottom surface of the circumferential groove. A plurality of provided, extending along the circumferential groove, and disposed at a bottom groove whose both ends are bent in a direction intersecting with the extending direction of the circumferential groove, and an intermediate portion in the longitudinal direction of the bottom groove; And a connecting portion that connects the groove walls facing each other.
In the pneumatic tire according to claim 1 of the present invention, the groove walls facing each other in the intermediate portion in the longitudinal direction of the bottom groove are connected by the connecting portion, so that the groove width direction ( Deformation in the tire axial direction) is suppressed. Thereby, in the land part adjacent to the circumferential groove, the rigidity in the tire axial direction at a position corresponding to the middle part of the bottom groove is improved.
Further, in the pneumatic tire, since the deformation of the intermediate portion of the bottom groove in the groove width direction can be suppressed by the connecting portion, it is possible to secure the drainage capacity of the bottom groove by increasing the groove width and groove depth of the bottom groove. it can.
As described above, according to the pneumatic tire of the first aspect, the rigidity of the land portion in the tire axial direction can be improved while ensuring the drainage performance.

The pneumatic tire according to claim 2 of the present invention is the pneumatic tire according to claim 1, wherein the upper surface of the connecting portion is at the same height as the bottom surface of the circumferential groove.
In the pneumatic tire according to claim 2 of the present invention, the rigidity of the land portion adjacent to the circumferential groove in the tire axial direction is ensured by making the upper surface of the connecting portion the same height as the bottom surface of the circumferential groove. However, the drainage performance of the water flowing in the circumferential groove can also be ensured.

A pneumatic tire according to a third aspect of the present invention is the pneumatic tire according to the first or second aspect, wherein the middle portion of the bottom groove is disposed at the center of the groove width of the circumferential groove. Yes.
In the pneumatic tire according to claim 3 of the present invention, since the middle portion of the bottom groove is arranged in the center of the groove width of the circumferential groove, the drainage water in the circumferential groove and the bottom groove can flow smoothly. Can do.

The pneumatic tire according to a fourth aspect of the present invention is the pneumatic tire according to any one of the first to third aspects, wherein the bottom surface of the circumferential groove extends from the center of the groove width toward the end. It is inclined or curved so as to be shallow, and the bent end portion of the bottom groove reaches the end portion of the bottom surface of the circumferential groove.
In the pneumatic tire according to claim 4 of the present invention, the bottom surface of the circumferential groove is inclined or curved so that the bottom surface of the circumferential groove becomes shallower from the center of the groove width toward the end portion. After the end of the contact surface becomes the ground contact surface, the land width of the land portions adjacent to the circumferential grooves increases with the progress of wear. As a result, the rigidity in the tire axial direction of both land portions is improved and the contact area with the road surface of both land portions is increased.
Further, in the pneumatic tire described above, since the bent end portion of the bottom groove reaches the end portion of the bottom surface of the circumferential groove, the end portion of the bottom surface of the circumferential groove is in contact with the wear as described above. After becoming the ground, the opening edge portion (edge) of the bent end portion of the bottom groove exhibits an edge effect, and wet performance is improved.

A pneumatic tire according to a fifth aspect of the present invention is the pneumatic tire according to any one of the first to fourth aspects, wherein the land portion adjacent to the circumferential groove has a tire extending from the circumferential groove. A plurality of sipes extending in a direction intersecting the circumferential direction are provided at intervals in the tire circumferential direction, and a portion of the land portion between the circumferential groove and the sipe is on the side of the circumferential groove of the sipe. An inclined portion whose height decreases toward the opening end is formed.
In the pneumatic tire according to claim 5 of the present invention, a plurality of sipes extending in a direction intersecting with the tire circumferential direction from the circumferential groove are provided in the land portion adjacent to the circumferential groove with an interval in the tire circumferential direction. Therefore, wet performance is improved by the edge effect of sipe.
Further, in the pneumatic tire, since a slope portion whose height decreases toward the opening end on the circumferential groove side of the sipe is formed in a portion between the circumferential groove and the sipe of the land portion, Water on the wet road surface can be smoothly drained to the circumferential groove through the inclined portion. Thereby, drainage performance further improves.

A pneumatic tire according to a sixth aspect of the present invention is the pneumatic tire according to the fifth aspect, wherein the connecting portion is provided at a position corresponding to the sipe.
In the pneumatic tire according to claim 6 of the present invention, since the connecting portion is provided at a position corresponding to the sipe, the portion where the rigidity is reduced by the sipe of the land portion adjacent to the circumferential groove is effective by the connecting portion. Can be reinforced.

  As described above, the pneumatic tire of the present invention can improve the rigidity of the land portion in the tire axial direction while ensuring the drainage performance.

It is an expanded view which shows the tread pattern which looked at the tire surface from the tire radial direction outer side of the pneumatic tire of 1st Embodiment. It is an enlarged view which shows 2X part of FIG. FIG. 3 is a cross-sectional view taken along line 3X-3X in FIG. 2. FIG. 4 is a perspective view of a cross section taken along line 4X-4X in FIG. 2. 5 is a cross section taken along line 5X-5X in FIG.

(First embodiment)
Hereinafter, a pneumatic tire according to a first embodiment of the present invention will be described.
A pneumatic tire (hereinafter simply referred to as “tire”) 10 according to the first embodiment is a tire mainly used for passenger cars. In addition, this invention is not limited to the pneumatic tire for passenger cars, You may use it for the pneumatic tire of other uses. For example, you may use for pneumatic tires for light trucks, aircrafts, and construction vehicles.

FIG. 1 is a development view of the tread 12 of the tire 10. 1 indicates the circumferential direction of the tire 10 (hereinafter referred to as “tire circumferential direction” as appropriate), and the arrow W indicates a direction parallel to the axis (rotation axis) of the tire 10 (hereinafter referred to as appropriate). It is described as “tire axial direction”). The tire axial direction may be read as the tire width direction.
Reference sign CL indicates an equatorial plane (hereinafter referred to as “tire equatorial plane” as appropriate) that is a plane that passes through the center of the tire 10 in the tire axial direction and is perpendicular to the tire axial direction.
In the present embodiment, the side near the tire equatorial plane CL along the tire axial direction is described as “inner side in the tire axial direction”, and the side far from the tire equatorial plane CL along the tire axial direction is described as “outer side in the tire axial direction”. To do.

  Further, reference numeral 12E in FIG. 1 indicates a grounding end of the tread 12. The term “grounding end” as used herein means that the tire 10 is mounted on a standard rim defined in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2012 version), and is applicable size and ply rating in JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-load capacity correspondence table in bold) and indicates the outer edge in the tire width direction of the contact surface when the maximum load capacity is applied. ing. Moreover, in the place of use or manufacturing place of the tire 10, the TRA standard or the ETRTO standard is applied instead of the JATMA standard.

The tire 10 of the present embodiment can use the same internal structure as that of a conventionally known pneumatic tire. For this reason, the description of the internal structure of the tire 10 is omitted.
As shown in FIG. 1, a tread 12 constituting a ground contact portion with the road surface of the tire 10 is provided with a center circumferential groove 14 extending linearly along the tire circumferential direction on the tire equator plane CL. In addition, the center circumferential groove | channel 14 of this embodiment is an example of the circumferential groove | channel provided with the bottom groove | channel of this invention.

  As shown in FIG. 3, the bottom surface 14 </ b> A of the center circumferential groove 14 is curved so as to become shallower from the center to the end of the groove width when viewed in the tire axial section. The bottom surface 14A may be inclined instead of curved.

As shown in FIG. 1, the tread 12 is provided with a pair of shoulder circumferential grooves 16 extending linearly along the tire circumferential direction on both sides of the center circumferential groove 14.
A center land portion 18 is formed between the center circumferential groove 14 and the shoulder circumferential groove 16 of the tread 12. The center land portion 18 is adjacent to the center circumferential groove 14. In addition, the center land part 18 of this embodiment is an example of the land part adjacent to the circumferential groove | channel of this invention.
On the other hand, a shoulder land portion 20 is formed on the outer side in the tire axial direction of the shoulder circumferential groove 16 of the tread 12.

As shown in FIGS. 1 and 2, the center land portion 18 is formed with a plurality of cutout portions 22 at regular intervals in the tire circumferential direction on the side wall 18 </ b> A on the shoulder circumferential groove 16 side.
The notch 22 has a groove shape, extends from the shoulder circumferential groove 16 toward the center circumferential groove 14, and terminates (is closed) in the center land portion 18. Further, the notch portion 22 of the present embodiment is formed from the surface 18S of the center land portion 18 to the bottom surface 16A of the shoulder circumferential groove 16, that is, is formed over the entire height of the center land portion 18. Yes. In addition, this invention is not limited to the said structure, The notch part 22 should just be formed in the surface 18S side of the center land part 18 at least.
Further, the center land portion 18 is formed with a first center sipe 24 extending from the terminal end portion 22 </ b> A of the notch portion 22 toward the center circumferential groove 14. A plurality of the first center sipes 24 are provided together with the notches 22 at intervals in the tire circumferential direction. In addition, the 1st center sipe 24 of this embodiment is an example of the sipe of this invention.

  The first center sipe 24 extends from the terminal end portion 22A of the notch 22 in a direction intersecting with the tire circumferential direction (in the present embodiment, oblique to the tire circumferential direction), and an angle with respect to the tire circumferential direction becomes small in the middle. It bends in this way and opens to the side wall 18B on the center circumferential groove 14 side. In addition, the depth of the first center sipe 24 of the present embodiment is the same as the depth of the center circumferential groove 14. The present invention is not limited to this configuration, and the depth of the first center sipe 24 may be shallower or deeper than the center circumferential groove 14.

As shown in FIGS. 2 and 4, a slope portion 26 is formed in a portion between the center circumferential groove 14 of the center land portion 18 and the first center sipe 24. The slope portion 26 is inclined so that the height decreases from the curved portion 24A of the first center sipe 24 toward the opening end 24B of the side wall 18B. In addition, the slope part 26 of this embodiment is an example of the inclination part of this invention.
The center land portion 18 is formed with a second center sipe 28 extending from the shoulder circumferential groove 16 toward the center circumferential groove 14 between the notch portions 22 adjacent to each other in the tire circumferential direction.

  The second center sipe 28 extends obliquely with respect to the tire circumferential direction and terminates in the center land portion 18. In addition, the depth of the second center sipe 28 in the present embodiment is the same as that of the first center sipe 24. The present invention is not limited to this configuration, and the depth of the second center sipe 28 may be different from that of the first center sipe 24, and may be shallower or deeper than the center circumferential groove 14. Good.

As shown in FIGS. 1 and 2, the center land portion 18 is divided into a plurality of portions in the tire circumferential direction by notches 22 and first center sipes 24 formed at regular intervals in the tire circumferential direction. In other words, the center land portion 18 includes a plurality of block-shaped land portions 30 partitioned by the notch portion 22 and the first center sipe 24.
Here, “sipe” refers to a narrow groove set to have a groove width such that the wall surfaces come into contact with each other and close at the time of grounding. Further, the grooves other than the sipe are set to a groove width at which the wall surfaces do not contact each other at the time of grounding.

As shown in FIG. 1, a plurality of shoulder lug grooves 32 are formed in the shoulder land portion 20 at regular intervals in the tire circumferential direction so as to straddle the ground contact end 12 </ b> E and intersect the tire circumferential direction. In the present embodiment, the shoulder lug grooves 32 are arranged at a half interval (half pitch) of the arrangement interval of the notch portions 22 adjacent in the tire circumferential direction.
In the shoulder lug groove 32, an end portion 32 </ b> A on the shoulder circumferential groove 16 side (tire equatorial plane CL side) terminates in the shoulder land portion 20.
A first shoulder sipe 34 extending from the end 32 </ b> A of the shoulder lug groove 32 toward the shoulder circumferential groove 16 is formed in the shoulder land portion 20.
The first shoulder sipe 34 opens to the side wall 20A of the shoulder land portion 20 on the shoulder circumferential groove 16 side.

As shown in FIG. 1, the shoulder land portion 20 is formed with a second shoulder sipe 36 extending along the tire circumferential direction between the first shoulder sipes 34 adjacent in the tire circumferential direction.
Further, the shoulder land portion 20 is divided into a plurality in the tire circumferential direction by shoulder lug grooves 32 and first shoulder sipes 34 formed at regular intervals in the tire circumferential direction within the ground contact surface. In other words, the shoulder land portion 20 is constituted by a plurality of block-shaped land portions 38 partitioned by the shoulder lug groove 32 and the first shoulder sipe 34 in the ground contact surface.

In the present embodiment, the inner side in the tire axial direction including the shoulder circumferential groove 16 of the tread 12 is a center portion, and the outer side in the tire axial direction of the center portion is a shoulder portion.
As shown in FIGS. 1 and 2, a bottom groove 40 extending along the center circumferential groove 14 is provided on the bottom surface 14 </ b> A of the center circumferential groove 14. A plurality of the bottom grooves 40 are arranged at intervals in the center circumferential groove 14 in the direction in which the center circumferential groove 14 extends (in the present embodiment, the tire circumferential direction). The bottom groove 40 of this embodiment is an example of the bottom groove of the present invention.

As shown in FIG. 2, both end portions 40 </ b> B in the longitudinal direction of the bottom groove 40 are bent in directions intersecting with the extending direction of the center circumferential groove 14.
On the other hand, the intermediate portion 40D in the longitudinal direction of the bottom groove 40 is disposed at the center of the groove width of the center circumferential groove 14 (hereinafter referred to as “groove center” as appropriate). The present invention is not limited to this configuration, and the intermediate portion 40D may be disposed closer to one side than the center of the groove width of the center circumferential groove 14.
In the present embodiment, the groove width of the intermediate portion 40D is wider than the bent end portion 40B of the bottom groove 40. In addition, this invention is not limited to this structure, The groove width of intermediate | middle part 40D may be narrower than the edge part 40B, and the groove width of the edge part 40B and intermediate | middle part 40D may be the same.

As shown in FIGS. 1 and 2, the intermediate portion 40 </ b> D of the bottom groove 40 is provided with a connecting portion 42 that connects the groove walls 40 </ b> A facing each other.
As shown in FIG. 5, the connecting portion 42 protrudes from the bottom surface 40C of the bottom groove 40 and is formed integrally with the groove wall 40A. Further, the connecting portion 42 is formed of the same rubber material as the rubber material forming the tread 12. In addition, this invention is not limited to this structure, You may comprise the connection part 42 and the tread 12 with a different rubber material (another rubber material), for example, comprises the connection part 42 with a rubber material harder than the tread 12. May be.

  In the present embodiment, the connecting portion 42 is raised from the bottom surface 40C of the bottom groove 40 and integrally formed with the groove wall 40A. However, the present invention is not limited to this configuration, and the connecting portion 42 is tread. 12 and a rubber material different from that of the bottom groove 40, and a configuration in which a gap is formed between the bottom surface 40C of the bottom groove 40 and the connecting portion 42. Good. In this case, water can flow through the gap.

Further, the upper surface 42A of the connecting portion 42 is at the same height as the bottom surface 14A of the center circumferential groove 14. The “same height” here refers to the distance from the axis (rotation axis) of the tire 10. Specifically, the upper surface 42A and the bottom surface 14A of the connecting portion 42 are flush with each other (see FIGS. 2 and 5).
In addition, this invention is not limited to this structure, You may arrange | position the upper surface 42A of the connection part 42 in the position which does not reach the bottom face 14A of the center circumferential groove | channel 14, ie, is lower than the bottom face 14A. In addition, when the upper surface 42A is set at a position lower than the bottom surface 14A, the water flowing in the bottom groove 40 easily exceeds the connecting portion 42, and the water flow becomes smooth.

As shown in FIG. 3, the end 40 </ b> B of the bottom groove 40 reaches the end of the bottom surface 14 </ b> A of the center circumferential groove 14 in the tire axial cross section.
Further, as shown in FIG. 1, the connecting portion 42 is provided at a position corresponding to the first center sipe 24. The “corresponding position” here means that the connecting portion 42 is provided in the tire axial direction of the first center sipe 24.
The end 40B of the bottom groove 40 is provided at a position corresponding to between the first center sipes 24 adjacent in the tire circumferential direction. The “corresponding position” referred to here indicates that the end portion 40B is provided in the tire axial direction between the first center sipes 24 adjacent in the tire circumferential direction.
As shown in FIG. 2, both end portions 40 </ b> B of the bottom groove 40 are bent in directions opposite to the tire axial direction. The end 40B of the bottom groove 40 is disposed between the first center sipes 24 adjacent in the tire circumferential direction.
In the present embodiment, the bottom surface 40C of the bottom groove 40 and the bottom surface 16A of the shoulder circumferential groove 16 have substantially the same height. That is, the center circumferential groove 14 is shallower than the shoulder circumferential groove 16.

Next, the effect of the tire 10 will be described.
In the tire 10, since the bottom groove 40 is provided on the bottom surface 14 </ b> A of the center circumferential groove 14, drainage performance can be ensured even if the depth of the center circumferential groove 14 is shallower than the shoulder circumferential groove 16. it can. In particular, by providing the bottom groove 40 while making the depth of the center circumferential groove 14 shallower than the shoulder circumferential groove 16, the center circumferential groove 14 is made shallow while securing drainage performance during straight traveling, Since the area of the cross section along the tire axial direction of the center land portion 18 is increased, the rigidity in the tire axial direction is improved.

  In the tire 10, the groove walls 40 </ b> A of the intermediate portion 40 </ b> D of the bottom groove 40 that are opposed to each other are connected by the connecting portion 42, and therefore the groove width direction (tire axial direction) of the intermediate portion 40 </ b> D of the bottom groove 40. Deformation (deformation in which the bottom groove 40 opens or closes) is suppressed. Thereby, in the center land portion 18 adjacent to the center circumferential groove 14, the rigidity in the tire axial direction at a position corresponding to the intermediate portion 40D of the bottom groove 40 is improved. Thereby, the steering stability at the time of turning improves.

  Furthermore, in the tire 10, since the deformation of the intermediate portion 40 </ b> D of the bottom groove 40 in the groove width direction can be suppressed by the connecting portion 42, the drainage capacity can be ensured by increasing the groove width and groove depth of the bottom groove 40. .

Further, since the connecting portion 42 is raised from the bottom surface 40C of the bottom groove 40, the rigidity of the connecting portion 42 is improved, and the rigidity in the tire axial direction of both the center land portions 18 adjacent to the center circumferential groove 14 is further increased. Can be secured.
Further, by making the upper surface 42A of the connecting portion 42 the same height as the bottom surface 14A of the center circumferential groove 14, while ensuring the rigidity in the tire axial direction of both center land portions 18 adjacent to the center circumferential groove 14, The drainage performance of the water flowing in the center circumferential groove 14 can also be ensured.

Further, since the intermediate portion 40D of the bottom groove 40 is provided at the center of the groove width of the center circumferential groove 14, the drainage in the center circumferential groove 14 and the bottom groove 40 can be smoothly flowed.
Since the bottom surface 14A of the center circumferential groove 14 is curved so as to become shallower from the center to the end of the groove width, the end of the bottom surface 14A of the center circumferential groove 14 becomes a ground contact surface due to wear. As the wear progresses, the land width of both center land portions 18 adjacent to the center circumferential groove 14 increases. As a result, the rigidity in the tire axial direction of both center land portions 18 is improved, and the contact area with the road surface of both center land portions 18 is increased.

  Since the end 40B of the bottom groove 40 reaches the end of the bottom surface 14A of the center circumferential groove 14, the end of the bottom surface 14A of the center circumferential groove 14 becomes a ground plane due to wear. The opening edge (edge) of the end portion 40B of the bottom groove 40 exhibits an edge effect, and wet performance is improved.

  In the tire 10, a plurality of first center sipes 24 extending from the center circumferential groove 14 in a direction intersecting with the tire circumferential direction are provided in the center land portion 18 adjacent to the center circumferential groove 14 at intervals in the tire circumferential direction. Therefore, the wet performance is improved by the edge effect of the first center sipe 24.

  Further, in the tire 10, a slope portion 26 whose height decreases toward the opening end 24 </ b> B of the first center sipe 24 is formed in a portion between the center circumferential groove 14 of the center land portion 18 and the first center sipe 24. Therefore, moisture on the wet road surface can be smoothly drained to the center circumferential groove 14 via the slope portion 26. Thereby, drainage performance further improves.

  Furthermore, since the connecting portion 42 is provided at a position corresponding to the first center sipe 24, a portion of which rigidity is reduced by the first center sipe 24 of the center land portion 18 adjacent to the center circumferential groove 14 is connected to the connecting portion. 42 can be effectively reinforced.

  In the tire 10, the end 40 </ b> B of the bottom groove 40 is not a portion where the rigidity is reduced by the first center sipe 24 of the center land portion 18 adjacent to the center circumferential groove 14, but the first center adjacent to the tire circumferential direction. Since it is provided at a position corresponding to between the sipes 24, the rigidity in the tire axial direction of the center land portion 18 adjacent to the center circumferential groove 14 can be made uniform in the tire circumferential direction.

  Further, since the notch portion 22 is provided in the center land portion 18, for example, the groove edge (opening edge portion of the groove) is different from the road surface when traveling as compared with the case where a lateral groove that crosses the center land portion 18 is provided. The hitting sound that occurs when a collision occurs can be reduced. That is, pattern noise can be reduced.

  Since the second shoulder sipe 36 is provided in the shoulder land portion 20, the water film on the surface of the land portion can be removed when the wet road surface enters. Thereby, the wet performance is improved. Moreover, since the center circumferential groove 14 is disposed on the tire equatorial plane CL, it is possible to effectively ensure drainage performance during straight traveling.

In the first embodiment, the bottom groove 40 is provided in the center circumferential groove 14, but the present invention is not limited to this structure, and the bottom groove 40 is provided in the shoulder circumferential groove 16 instead of the center circumferential groove 14. The bottom groove 40 may be provided in the shoulder circumferential groove 16 in addition to the center circumferential groove 14.
In the first embodiment, the tread 12 is provided with three circumferential grooves. However, the present invention is not limited to this configuration, and the tread may be provided with only one circumferential groove. Alternatively, four or more may be provided. In this case, the bottom groove 40 may be provided in at least one of the circumferential grooves.

  In the first embodiment, one connecting portion 42 is provided in the intermediate portion 40D of the bottom groove 40, but the present invention is not limited to this configuration, and a plurality of connecting portions 42 are provided in the intermediate portion 40D of the bottom groove 40. Also good.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

10 Tire (Pneumatic tire)
12 tread 14 center circumferential groove (circumferential groove)
14A bottom surface 18 center land part (land part adjacent to circumferential groove)
24 1st Center Sipe (Sipe)
26 Slope (inclined part)
40 bottom groove 40A groove wall 40B end 42 connecting portion 42A upper surface CL tire equatorial plane S tire circumferential direction W tire axial direction

Claims (6)

A circumferential groove provided in the tread and extending along the tire circumferential direction;
A plurality of grooves are provided on the bottom surface of the circumferential groove at intervals in the extending direction of the circumferential groove, extend along the circumferential groove, and both ends are bent in a direction intersecting with the extending direction of the circumferential groove. The bottom groove,
A connecting portion that is disposed at an intermediate portion in the longitudinal direction of the bottom groove and connects the groove walls facing each other;
Pneumatic tire having   The pneumatic tire according to claim 1, wherein an upper surface of the connecting portion is at the same height as a bottom surface of the circumferential groove.   The pneumatic tire according to claim 1 or 2, wherein an intermediate portion of the bottom groove is disposed at a center of a groove width of the circumferential groove. The bottom surface of the circumferential groove is inclined or curved so as to become shallower toward the end from the center of the groove width,
The pneumatic tire according to claim 1, wherein the bent end portion of the bottom groove reaches the end portion of the bottom surface of the circumferential groove. In the land portion adjacent to the circumferential groove, a plurality of sipes extending from the circumferential groove in a direction intersecting the tire circumferential direction are provided at intervals in the tire circumferential direction,
The inclined portion whose height decreases toward the opening end on the circumferential groove side of the sipe is formed at a portion of the land portion between the circumferential groove and the sipe. The pneumatic tire according to any one of 4.   The pneumatic tire according to claim 5, wherein the connecting portion is provided at a position corresponding to the sipe.

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