JP2016175576A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving performance at braking time and handling time.SOLUTION: In a pneumatic tire having a tread 10 provided with a main groove 12 extending in a tire circumferential direction and lateral grooves 20A, 20B, and 20C extending in a tire width direction, a chamfered oblique wall part 28 is disposed on an opening end part toward a ground plane 11, on at least one of groove wall surfaces 26 in the lateral grooves. On the oblique wall part 28, a first concave part 32 extending in a width direction of the oblique wall part, and a second concave part 34 extending in a longitudinal direction of the oblique wall part are disposed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire.

  Generally, a tread of a pneumatic tire is provided with a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction, and a plurality of land portions are formed by the main groove and the lateral groove. In such a pneumatic tire, a large contact pressure is applied near the end of the land during braking or handling, and the contact pressure in the contact surface of the land becomes uneven. As a result, the braking performance and handling performance are poor.

  On the other hand, as described in Patent Document 1, there is a pneumatic tire in which a chamfered inclined wall portion is provided at an end portion of a land portion. In such a pneumatic tire, the contact pressure applied to the vicinity of the end portion of the land portion is reduced, and the contact pressure in the contact surface of the land portion is made uniform. Therefore, braking performance and handling performance can be improved.

  As what provided the said chamfered inclined wall part, in patent document 2, after providing the chamfered inclined wall part in the groove wall surface of the main groove, the width direction of the said inclined wall part is provided in this inclined wall part. It has been proposed to provide a plurality of fine grooves extending in the direction. Further, this document discloses that a fine groove may be provided by forming a slant wall portion on the groove wall surface of the lateral groove. In this document, the fine groove is provided to improve the wettability of the inclined wall portion and improve the drainage.

Japanese Patent Laid-Open No. 2002-036826 JP 2003-146024 A

  When a chamfered inclined wall is provided on the groove wall surface of the horizontal groove, and a recess is provided in the inclined wall, the inclined wall is in contact with the road surface due to deformation of the land during braking and handling, and the recess provided in the inclined wall. The performance improvement can be expected by the edge effect. However, since the recess extending in the width direction of the inclined wall portion is a recess extending in the tire circumferential direction, it is possible to improve the performance in the tire width direction by generating a force in the tire width direction when turning the vehicle due to the edge effect. However, it is difficult to exhibit the edge effect in the tire circumferential direction during braking, and it is difficult to improve the performance in the tire circumferential direction.

  Then, an object of this invention is to provide the pneumatic tire which can aim at the further performance improvement at the time of braking and handling.

  The pneumatic tire according to an embodiment of the present invention is a pneumatic tire in which a tread is provided with a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction, and at least one groove wall surface of the lateral groove is A sloping wall portion having a chamfered shape at an opening end to the ground surface, a first recess extending in the width direction of the sloping wall portion, and a second extending in the longitudinal direction of the sloping wall portion. A recess is provided.

  According to the present embodiment, after the inclined wall portion is provided on the groove wall surface of the horizontal groove, the first concave portion extending in the width direction and the second concave portion extending in the longitudinal direction are provided on the inclined wall portion, so that during braking, Further improvement in performance during handling can be achieved.

The figure which shows the tread pattern of the pneumatic tire which concerns on 1st Embodiment. II-II sectional view taken on the line of FIG. The principal part perspective view of the block which shows the inclined wall part which concerns on 1st Embodiment. FIG. 4 is a plan view of the inclined wall portion of FIG. 3. The principal part perspective view of the block which shows the inclined wall part which concerns on 2nd Embodiment. FIG. 6 is a plan view of the inclined wall portion of FIG. The top view of the inclined wall part which concerns on 3rd Embodiment. The top view of the inclined wall part which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
The pneumatic tire according to the embodiment is not illustrated, but the pair of left and right bead portions and sidewall portions and the radially outer ends of the left and right sidewall portions are connected to each other between the sidewall portions. The tread 10 is provided, and a general tire structure can be adopted except for the tread pattern.

  As shown in FIG. 1, a plurality of main grooves 12 extending in the tire circumferential direction R are provided on the surface of the tread 10. In this example, the four main grooves 12 cause the center rib 14 at the center in the tire width direction, the shoulder ribs 18 and 18 on both sides in the tire width direction, and the mediate ribs 16 and 16 between the center rib 14 and the shoulder rib 18. The five ribs are defined as land portions. In FIG. 1, the symbol CL indicates the tire equator.

  The center rib 14 and the shoulder rib 18 are provided with a plurality of transverse grooves 20A, 20B, 20C extending in the tire width direction at intervals in the tire circumferential direction R. In this example, the lateral groove 20 </ b> A provided in the center rib 14 crosses the center rib 14. Therefore, the center rib 14 is formed as a block row in which a plurality of block-shaped land portions 22 divided by the lateral grooves 20A are arranged in parallel in the tire circumferential direction R. The lateral groove 20A is not perpendicular to the tire circumferential direction R but extends obliquely with respect to the tire axial direction. Thus, the lateral groove extending in the tire width direction only needs to extend in a direction intersecting the tire circumferential direction, and is not limited to one extending in parallel to the tire axial direction.

  The lateral grooves provided in the shoulder rib 18 include a lateral groove 20B that opens to the main groove 12 and a lateral groove 20C that does not open to the main groove 12, and these are alternately arranged in the tire circumferential direction R. Thereby, although the shoulder rib 18 is not completely divided by the lateral grooves 20B and 20C, a plurality of land portions 24 partitioned by the lateral grooves are provided side by side in the tire circumferential direction R. The lateral grooves 20B and 20C are formed to extend obliquely with respect to the tire axial direction while being curved so as to be convex in the tire circumferential direction R in a plan view shown in FIG.

  The groove wall surfaces 26 on both sides of the lateral grooves 20A, 20B, and 20C are provided with chamfered inclined wall portions 28 at the opening ends to the ground surface. Specifically, as shown in FIG. 2, the groove wall surfaces 26 on both sides of the lateral grooves 20A, 20B, and 20C are formed on the main wall portion 30 forming the inner portion in the tire radial direction and the outer portion in the tire radial direction. It is composed of a chamfered inclined wall portion 28 that inclines in the direction of increasing the groove width toward the ground 11.

  As shown in FIG. 1, in the horizontal groove 20A provided in the center rib 14, the inclined wall portion 28 is formed over the entire width of the center rib 14, that is, provided in the entire extending direction of the horizontal groove 20A. .

  Regarding the shoulder rib 18, in the lateral groove 20 </ b> B that opens to the main groove 12, the slant wall portion 28 of one groove wall surface 26 </ b> A extends to the open end of the lateral groove 20 </ b> B with respect to the main groove 12, while the other The inclined wall portion 28 of the groove wall surface 26B terminates at a position that does not reach the opening end. As for the outer end in the tire width direction, the inclined wall portion 28 extends to a position beyond the ground contact CE in both the groove wall surfaces 26A and 26B. Further, in the lateral groove 20C that does not open in the main groove 12, the inclined wall portion 28 extends from the position beyond the ground contact end CE outward in the tire width direction to the inner end in the tire width direction of the lateral groove 20C in the groove wall surfaces 26 on both sides. Exist.

  Here, the ground contact edge CE is formed on the ground contact surface of a tread that rims the tire on a regular rim, places the tire vertically on a flat road surface with normal internal pressure filled, and contacts the road surface when a normal load is applied. This is the outermost position in the tire axial direction. The regular rim is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim is used for JATMA, “Design Rim” is used for TRA, and “Measuring” is used for ETRTO. Rim ". The normal internal pressure is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table is TRA. In the case of ETRTO, the maximum value described in "INFLATION PRESSURE" is used, but when the tire is for a passenger car, it is 180 kPa. In addition, the normal load is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. If it is JATMA, it is the maximum load capacity, and if it is TRA, the maximum load described in the above table. If the value is ETRTO, it is “LOAD CAPACITY”, but if the tire is for a passenger car, the load is equivalent to 88% of the load. In the following, unless otherwise specified, the dimensions of each part of the tire are values in a no-load state in which the tire is assembled on a regular rim and filled with a regular internal pressure.

  As for the cross-sectional shape of the slant wall portion 28 (cross-sectional shape cut along the tire circumferential direction), as shown in FIG. 2, the tire circumferential direction length of the land portions 22 and 24 is W, and the tire circumference of the slant wall portion 28 is When the length in the direction is A, the height of the land portions 22 and 24 (the same as the depth of the lateral grooves 20A, 20B, and 20C) is D, and the height of the inclined wall portion 28 is B, the A / W is 0.05 to It is preferably 0.4, and may be 0.2 to 0.3. Moreover, it is preferable that B / D is 0.2-0.5. About the circumferential length A and the height B of the inclined wall portion 28, if these are too small, the effect of lowering the contact pressure at the stepped side and the kicked side end portions of the land portions 22 and 24 becomes insufficient. The effect of equalizing the contact pressure in the contact surface is reduced.

  Here, the tire circumferential direction length W of the land portions 22 and 24 is the main wall portion 30 of the groove wall surface 26 on one side of the land portions 22 and 24 sandwiched between two lateral grooves adjacent in the tire circumferential direction. To the main wall portion 30 of the groove wall surface 26 on the other side in the tire circumferential direction R, and an average value when it varies in the tire width direction. Further, the height D of the land portions 22 and 24 refers to the bottom surface of the horizontal grooves 20A, 20B, and 20C (the flat surface when the bottom of the horizontal groove is a flat surface, and the deepest portion of the curved surface when the horizontal groove is a curved surface). The distance in the tire radial direction. The tire circumferential direction length A of the inclined wall portion 28 is the distance in the tire circumferential direction R from the end 28E on the groove bottom side of the inclined wall portion 28 to the end on the ground contact surface 11 side. The height B of the inclined wall portion 28 is a distance in the tire radial direction from the groove bottom side end 28E of the inclined wall portion 28 to the ground contact surface 11.

  As shown in FIGS. 2 to 4, the inclined wall portion 28 is provided with a first recessed portion 32 extending in the width direction of the inclined wall portion 28 and a second recessed portion 34 extending in the longitudinal direction of the inclined wall portion 28. Here, the longitudinal direction of the inclined wall portion 28 is a direction along the extending direction of the lateral grooves 20A, 20B, and 20C, and corresponds to the tire width direction. Further, the width direction of the inclined wall portion 28 is a direction intersecting the longitudinal direction (preferably a direction orthogonal), and is a direction along the inclined direction of the inclined wall portion 28 (in the plan view, substantially the tire circumferential direction). Equivalent to

  Although the depth e of the 1st recessed part 32 and the 2nd recessed part 34 is not specifically limited, It is preferable that it is 0.5-1.0 mm. By providing this depth, it is possible to suppress the collapse of the recesses 32 and 34 during braking due to a decrease in rigidity of the land portions 22 and 24 while exhibiting the effect of providing the recesses in the inclined wall portion 28. This makes it easier to demonstrate good drainage performance on wet road surfaces.

  At least one pair of the first recess 32 and the second recess 34 may be provided. In this example, a plurality of the first recesses 32 and the second recesses 34 are alternately arranged in the longitudinal direction of the inclined wall portion 28. Yes.

  The first concave portion 32 has a rectangular shape that is long in the width direction of the inclined wall portion 28, and its extending length is 50 to 80% of the width of the inclined wall portion 28, and the width is the width of the inclined wall portion 28. Is set to 20 to 40%. That is, the width of the inclined wall portion 28 (the length in the width direction of the inclined wall portion 28 (the direction orthogonal to the extending direction)) is H, the extended length of the first recessed portion 32 is a, and the first recessed portion The width of 32 (the length in the direction perpendicular to the extending direction of the first recess 32) is b, and a / H is 0.5 to 0.8 and b / H is 0.2 to 0.4. It is preferably set. The first recess 32 extending in the width direction of the inclined wall portion 28 may extend in a direction intersecting the longitudinal direction of the inclined wall portion 28 and is not limited to one extending in a direction orthogonal to the longitudinal direction. . For example, in the inclined wall portion 28 of the lateral groove 20 </ b> A extending obliquely with respect to the tire axial direction as described above, the first recessed portion 32 is installed so as to extend parallel to the tire circumferential direction R in plan view.

  The second concave portion 34 has a rectangular shape that is long in the longitudinal direction of the inclined wall portion 28, and its extension length is 50 to 80% of the width of the inclined wall portion 28, and the width is the inclined wall portion 28. The width is set to 20 to 40%. That is, the extension length of the second recess 34 is c, the width of the second recess 34 (the length in the direction perpendicular to the extension direction of the second recess 34) is d, and c / H is 0.5 to 0.5. It is preferable that 0.8 and d / H be set to 0.2 to 0.4.

  In addition, the distance f between the 1st recessed part 32 and the 2nd recessed part 34 is not specifically limited, You may be smaller than the extended length c of the 2nd recessed part 34, or this extended length c That's all.

  Further, the width H of the inclined wall portion 28 may be the same or different between the groove wall surfaces 26 on both sides of the lateral grooves 20A, 20B, and 20C. For example, in the example of FIG. 1, in the lateral groove 20A of the center rib 14, the width H of the inclined wall portion 28 is the same on the groove wall surfaces 26 on both sides. On the other hand, in the lateral grooves 20B and 20C of the shoulder rib 18, the width H of the inclined wall portion 28 is not the same on the groove side walls 26 on both sides, and the wide inclined wall portion and the narrow inclined wall portion are provided to face each other. Yes. The extension lengths a and c and the widths b and d of the first recess 32 and the second recess 34 may be the same or different at the groove wall surfaces 26 on both sides of the lateral grooves 20A, 20B, and 20C. When the width H is different, the width H can be appropriately set according to the width H.

  In the present embodiment configured as described above, the inclined wall portions 28 are provided at the end portions of the land portions 22 and 24 on the stepping-in side and the kicking-out side, so that an increase in the ground pressure at these end portions can be suppressed and contacted. It is possible to make the contact pressure uniform in the ground. Therefore, the braking distance on a dry road surface or a wet road surface can be reduced, and handling performance can be improved. In addition, since the drainage performance is improved by providing the inclined wall portion 28, the performance on the wet road surface can be improved also in this respect.

  Further, by providing the inclined wall portion 28 with the first concave portion 32 and the second concave portion 34, the road surface aggregate enters and gets caught in the concave portions 32 and 34 during braking and handling, thereby increasing the frictional force and improving the performance. can do. More specifically, as a means for improving the frictional force, for example, it is conceivable to provide a recess in the ground contact surface 11 of the land portions 22 and 24. However, in that case, the ground contact area is reduced, the cornering power is reduced, and the improvement in handling performance is small. On the other hand, when the concave portions 32 and 34 are provided in the inclined wall portion 28 as in the present embodiment, the inclined wall portion 28 comes into contact with the road surface due to deformation of the land portions 22 and 24 during braking or handling, and the concave portion 32 is provided. , 34 exhibits the edge effect. Therefore, the edge effect can be exhibited without reducing the ground contact area, which is advantageous in improving braking performance and handling performance. In addition, the provision of the recesses 32 and 34 can increase the volume of the water flow, which is advantageous in terms of drainage effect on the wet road surface.

  In addition, since the first concave portion 32 extending in the width direction of the inclined wall portion 28 and the second concave portion 34 extending in the longitudinal direction of the inclined wall portion 28 are provided in combination, the edge effect is obtained both during braking and during handling. It can be demonstrated. That is, at the time of braking, since the second recess 34 is a recess extending in the tire width direction, the edge effect at the second recess 34 is large, and therefore a force is generated in the tire circumferential direction to improve the braking performance. Can do. On the other hand, at the time of handling (when turning the vehicle), since the first recess 32 is a recess extending in the tire circumferential direction, the edge effect at the first recess 32 is large, and therefore a force is generated in the tire width direction. , Handling performance can be improved.

  As described above, according to the present embodiment, the chamfered inclined wall portion 28 is provided at the stepping-side and kicking-out ends of the land portions 22 and 24, and the tire circumferential direction is provided on the inclined wall portion 28. By providing the first recess 32 directed to R and the second recess 34 directed to the tire width direction, both braking performance and handling performance can be improved.

[Second Embodiment]
The configuration of the inclined wall portion according to the second embodiment will be described with reference to FIGS. In 2nd Embodiment, the structure of the 1st recessed part 42 and the 2nd recessed part 44 which are provided in the inclined wall part 28 differs from 1st Embodiment.

  In the second embodiment, a plurality of first recesses 42 extending in the width direction of the inclined wall portion 28 are arranged at equal intervals in the longitudinal direction of the inclined wall portion 28, and then the second recess 44 is replaced with the plurality of first recesses. 42 are formed in a groove shape extending in the longitudinal direction of the inclined wall portion 28 so as to connect them.

  Specifically, the first recess 42 has a rectangular shape that is long in the width direction of the inclined wall portion 28. The size of the first recess 42 is 50 to 80% of the width H of the inclined wall portion 28 (a / H = 0.5 to 0.8), as in the first embodiment. In addition, the width b can be set to 20 to 40% (b / H = 0.2 to 0.4) of the width H of the inclined wall portion 28. The distance g between the 1st recessed parts 42 is not specifically limited, For example, you may set to the same grade as the width | variety b of the 1st recessed part 42 (g / b = 0.5-2).

  On the other hand, the second recessed portion 44 extends in the longitudinal direction of the inclined wall portion 28 so as to penetrate the first recessed portion 42 in the central portion in the extending direction of the first recessed portion 42 and connect the plurality of first recessed portions 42. It is provided in a continuous narrow groove shape. The width d of the second recess 44 is not particularly limited, and may be set equal to or less than the width b of the first recess 42.

  The second recess 44 may be formed so as to terminate in the inclined wall portion 28, but is preferably provided so as to open to the main groove 12. For example, FIG. 5 shows the inclined wall portion 28 of the lateral groove 20 </ b> A provided in the center rib 14. As shown in FIG. 1, the horizontal groove 20A is provided in the main groove 12 so as to be open as in the first embodiment, and the inclined wall portion 28 is formed over the entire extending direction of the horizontal groove 20A. As shown in FIGS. 5 and 6, the second recess 44 extends to the end of the inclined wall portion 28 on the main groove 12 side, so that the second recess 44 opens into the main groove 12. Is provided. In this example, the second concave portion 44 is provided over the entire extending direction of the inclined wall portion 28, and therefore, the second concave portion 44 is open to the main grooves 12 on both sides of the center rib 14.

  In addition, about the 1st recessed part and 2nd recessed part which are provided in the inclined wall part 28 of the shoulder rib 18, you may provide the 1st recessed part 42 and the 2nd recessed part 44 similar to the center rib 14, or 1st Embodiment. You may provide the 1st recessed part 32 and the 2nd recessed part 34 similar to. In the former case, with respect to the lateral groove 20B that opens to the main groove 12, the second concave portion 44 is formed in the main groove 12 in the inclined wall portion 28 of the groove wall surface 26A that extends to the opening end. You may provide so that it may open to.

  In the second embodiment, the second recessed portion 44 is formed in a groove shape extending in the longitudinal direction of the inclined wall portion 28 and connecting the plurality of first recessed portions 42, that is, the recessed portion provided in the inclined wall portion 28. Since 42 and 44 are connected by the extending direction of 20 A of horizontal grooves, the further drainage effect is acquired and the performance in a wet road surface can be improved. Moreover, drainage can be further improved by the 2nd recessed part 44 opening to the main groove 12. FIG. About 2nd Embodiment, about another structure and an effect, it is the same as that of 1st Embodiment, and description is abbreviate | omitted.

[Third Embodiment]
Based on FIG. 7, the structure of the inclined wall part which concerns on 3rd Embodiment is demonstrated. In 3rd Embodiment, the shape of the 1st recessed part 42 differs from 2nd Embodiment. That is, the 1st recessed part 42 of 3rd Embodiment makes the ellipse shape extended in the width direction of the inclined wall part 28 instead of a rectangular shape. Here, the oval shape is not limited to an elliptical shape, and includes, for example, a track shape. Thus, the shape of the first recess 42 is not particularly limited as long as it has a shape that is long in the width direction of the inclined wall portion 28, and various shapes can be employed. This also applies to the first recess 32 and the second recess 34 in the first embodiment. In addition, each dimension setting a, b, d, and g in the third embodiment can be set similarly to the second embodiment. About 3rd Embodiment, about another structure and an effect, it is the same as that of 2nd Embodiment, and description is abbreviate | omitted.

[Fourth Embodiment]
Based on FIG. 8, the structure of the inclined wall part which concerns on 4th Embodiment is demonstrated. In 4th Embodiment, the structure of the 1st recessed part 42 provided in the inclined wall part 28 differs from 2nd Embodiment.

  The fourth embodiment is characterized in that the first recess 42 is formed by shifting the phase vertically. That is, the first concave portion 42 includes an upper concave portion 42A that extends from the second concave portion 44 toward the ground contact surface 11 side, and a lower concave portion 42B that extends from the second concave portion 44 toward the groove bottom side. The upper concave portion 42A and the lower concave portion 42B are provided at positions shifted in the longitudinal direction of the inclined wall portion 28.

  Thus, by arranging the upper concave portion 42A and the lower concave portion 42B of the first concave portion 42 so as to be out of phase, the narrow groove-shaped second portion without narrowing the arrangement interval of the first concave portions 42. The dimension of the narrowest part 44A of the recess 44 can be reduced. As shown in FIG. 8, the narrowest width portion 44 </ b> A is a portion of the second recess 44 where the upper recess portion 42 </ b> A and the lower recess portion 42 </ b> B of the first recess 42 are not extended vertically. By disposing the upper concave portion 42A and the lower concave portion 42B in a shifted manner, the size of the narrowest width portion 44A is reduced, so that the confinement of the second concave portion 44 that occurs during tire braking can be reduced. Therefore, for example, it is advantageous in improving drainage performance on a wet road surface.

  In addition, each dimension setting a, b, d, and g in the fourth embodiment can be set similarly to the second embodiment. About 4th Embodiment, about another structure and an effect, it is the same as that of 2nd Embodiment, and description is abbreviate | omitted.

[Other Embodiments]
In the above embodiment, the inclined wall portions 28 are provided on the groove wall surfaces 26 on both sides of each of the lateral grooves 20A, 20B, 20C, but the inclined wall portions 28 may be provided on any one of the groove wall surfaces 26.

  In the above embodiment, the lateral grooves 20A, 20B, and 20C have been described with reference to a groove having a groove width of 1.8 mm or more, which is generally referred to as a sub-groove. However, the present invention may be applied to a narrow groove having a groove width of 1.5 mm or less, generally called a sipe.

  Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  In order to confirm the effect of the above embodiment, the braking distance and handling performance of the pneumatic tires of the examples and comparative examples were examined.

  The pneumatic tire of an example is a pneumatic radial tire for passenger cars having a tire size of 225 / 50R17, which has the characteristics of the first embodiment. Each dimension in the center rib 14 and the shoulder rib 18 is as follows.

Center rib: W = 25.0 mm, D = 8.0 mm, A = 3.0 mm, B = 3.0 mm, H = 4.0 mm, a = 2.0 mm, b = 1.0 mm, c = 2. 0mm, d = 1.0mm, f = 2.8mm
・ Shoulder rib: W = 20.0 mm, D = 5.0 mm,
(Wide oblique wall portion) A = 2.5 mm, B = 2.5 mm, H = 3.3 mm, a = 2.0 mm, b = 1.0 mm, c = 2.0 mm, d = 1.0 mm, f = 2.8mm
(Narrow-width oblique wall portion) A = 2.0 mm, B = 2.0 mm, H = 2.6 mm, a = 1.5 mm, b = 1.0 mm, c = 1.5 mm, d = 1.0 mm, f = 2.8mm

  The pneumatic tire of the comparative example is an example in which the first concave portion 32 and the second concave portion 34 are not provided in the inclined wall portion, and other configurations are the same as those in the embodiment including the configuration of the inclined wall portion.

The evaluation method of braking distance and handling performance is as follows.
-Braking distance: Pneumatic tires were filled with vehicle-designated air pressure, assembled into a standard rim, and attached to the vehicle. The vehicle was driven at a speed of 100 km / h on the road surface of a 1 mm water film, a full brake was applied, and the distance to stop was measured. The reciprocal of the distance until stopping was taken, and the reciprocal was displayed as an index with the value of the comparative example as 100. A larger index means a shorter braking distance and better braking performance.

・ Handling performance: Pneumatic tires were filled with the air pressure specified by the vehicle, assembled into a standard rim, and attached to the vehicle. The vehicle was subjected to straight running, lane change, and slalom at a speed of 140 to 160 km / h on the road surface of a 1 mm water film, and the performance at that time was subjected to sensory evaluation, and the evaluation of the comparative example was displayed as an index. The larger the index, the better the handling performance.

  The results are as shown in Table 1, and both the braking distance and the handling performance are higher in the index than in the comparative example. That is, the pneumatic tire according to the example is oblique to the pneumatic tire in the comparative example. By providing the first concave portion and the second concave portion in the wall portion, both the braking performance and the handling performance were improved.

DESCRIPTION OF SYMBOLS 10 ... Tread, 11 ... Ground surface, 12 ... Main groove, 20A, 20B, 20C ... Lateral groove, 26 ... Groove wall surface, 28 ... Oblique wall part, 32, 42 ... 1st recessed part, 34, 44 ... 2nd recessed part, 42A ... upper concave part, 42B ... lower concave part, H ... width of the inclined wall part, a ... extension length of the first concave part, b ... width of the first concave part, c ... extension length of the second concave part, d: Width of the second recess

Claims (6)

A pneumatic tire provided with a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction on the tread,
At least one groove wall surface of the lateral groove has a chamfered inclined wall portion at an opening end to the grounding surface, the inclined wall portion includes a first recess extending in a width direction of the inclined wall portion, and the inclined wall surface. A second recess extending in the longitudinal direction of the wall is provided,
Pneumatic tire. The first recesses and the second recesses are provided alternately in the longitudinal direction of the inclined wall portion,
The pneumatic tire according to claim 1. The first recess extending in the width direction of the inclined wall portion has an extension length of 50 to 80% of the width of the inclined wall portion and a width of 20 to 40% of the width of the inclined wall portion, The second recess extending in the longitudinal direction of the inclined wall portion has an extending length of 50 to 80% of the width of the inclined wall portion and a width of 20 to 40% of the width of the inclined wall portion.
The pneumatic tire according to claim 2. A plurality of the first recesses are provided side by side in the longitudinal direction of the inclined wall portion, and the second recesses are formed in a groove shape extending in the longitudinal direction of the inclined wall portion and connecting the plurality of first recesses.
The pneumatic tire according to claim 1. The lateral groove is provided to open to the main groove, and the second recess extends to the end of the inclined wall portion on the main groove side, and is provided to open to the main groove.
The pneumatic tire according to claim 4. The first recess includes an upper recess extending from the second recess toward the ground surface and a lower recess extending from the second recess toward the groove bottom, and the upper recess and the lower recess. The portion is provided at a position shifted in the longitudinal direction of the inclined wall portion,
The pneumatic tire according to claim 4 or 5.

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