JP6251082B2 - tire - Google Patents

Description

  The present invention relates to a tire, and more particularly to a pneumatic tire according to an improvement in the surface shape of the tire.

  Conventionally, a tire mounted on a vehicle such as a passenger car has a problem of road noise that occurs when the tire rolls on a road surface having irregular irregularities such as a rough paved road. . In order to reduce this road noise, for example, in the buttress part located between the tread part and the sidewall part, by forming a plurality of recesses along the tire circumferential direction, the road noise caused by the vibration of the buttress part A technique for reducing the above is known (see, for example, Patent Document 1).

JP 2011-68334 A

  On the other hand, the buttress part repeatedly deforms due to distortion in the tire radial direction when the vehicle is running. Therefore, if a recess is provided in the buttress part, local concentration of strain tends to occur in the recess, and cracks may occur during long-term use. There is a concern that will occur. Therefore, when the deepest part of the concave portion is continuously arranged in the circumferential direction, a crack may be connected at the part, resulting in a crack. Usually, such a crack does not cause a problem in the performance of the tire, but there is a possibility that the appearance is deteriorated.

  Accordingly, an object of the present invention is to provide a tire that reduces road noise while suppressing a decrease in appearance due to use.

As a result of intensive studies, the present inventor has found that the above-described problem can be solved by adopting the following configuration, and has completed the present invention.
That is, the tire of the present invention, in a tire comprising a tread portion that is in contact with the road surface, and a buttress portion provided on the outer side of the tread portion in the tire width direction,
A plurality of recesses recessed toward the inner surface of the tire are provided on the surface of the buttress portion along the tire circumferential direction, and the bottom portion having the deepest depth is located at the outer edge of the recess, The depth gradually changes from the surface of the buttress part to the bottom part, the circumferential length of the bottom part is smaller than the maximum value of the circumferential length of the concave part, and the circumferential length of the concave part is The depth of the concave portion gradually decreases from the shallowest position to the deepest position along the tire surface, and a corner is formed by a straight line or a curve at the bottom, and the corner is sandwiched between The angle is a right angle or an obtuse angle.

  In the tire of the present invention, it is preferable that the recesses adjacent in the tire circumferential direction are offset from each other in a direction orthogonal to the tire circumferential direction along the tire surface. Further, the depth of the concave portion is changed in a direction perpendicular to the tire circumferential direction along the tire surface, and the concave portions adjacent in the tire circumferential direction are opposite to each other in the depth changing direction. It is preferable to arrange so as to be.

  Furthermore, in the tire of the present invention, the depth of the bottom is preferably in the range of 0.5 mm to 1.5 mm. Furthermore, the maximum value of the circumferential length of the concave portion is the outermost land portion partitioned by a plurality of circumferential grooves on the contact surface of the tread portion, and the buttress portion provided with the concave portion. It is preferable that it is below the circumferential direction distance between the lug groove and / or sipe which are arrange | positioned in the adjacent land part in the tire width direction. Furthermore, it is preferable that a plurality of the recesses are provided in a direction perpendicular to the tire circumferential direction along the tire surface, and in the recesses adjacent to each other in the tire circumferential direction, It is preferable that the positions in the direction orthogonal to the tire circumferential direction are different.

  According to the present invention, a plurality of concave portions are provided on the surface of the buttress portion along the tire circumferential direction, and the bottom portion having the deepest depth is positioned at the outer edge of the concave portion. Gradually changing from the surface of the part to the bottom part, and the circumferential length of the bottom part is made smaller than the maximum value of the circumferential length of the concave part, so that the effect of reducing the road noise is obtained. Occurrence, and in turn, occurrence of cracks that lead to the circumferential direction of the tire can be suppressed, and it has become possible to realize a tire that suppresses deterioration in appearance due to use.

It is a partial development view showing a tread part of an example of the tire of the present invention, and the field of the tire width direction outside. (A) of a recessed part formation area is a partial enlarged view, (b) is a fragmentary sectional view. (A)-(c) is a top view of the other specific example of a recessed part. (A)-(d) is sectional drawing of the other specific example of the recessed part shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial development view showing a tread portion of an example of a tire of the present invention and a region outside the tire width direction. In the figure, when the tire circumferential direction is viewed as the vertical direction, the right direction is the vehicle mounting inner side and the left direction is the vehicle mounting outer side. As shown in the drawing, the tire of the present invention has a directional pattern in which the mounting direction with respect to the vehicle is designated.

  In the illustrated tire of the present invention, four circumferential grooves 1a to 1d extending continuously in the tire circumferential direction are arranged on the ground contact surface of the tread portion 101, and these four circumferential grooves 1a to 1d are arranged. Thus, the land portions 2a to 2e are partitioned. In the illustrated tire, there is no circumferential groove on the tire equatorial plane CL, and a land portion 2c continuous in the tire circumferential direction is disposed.

  In the tire of the present invention, a buttress portion 102 is disposed outside the tread portion 101 in the tire width direction. The buttress portion 102 is a tread portion 101 in a region from the ground contact end TE of the tread portion 101 to the tire maximum width position in a state in which the tire is mounted on an applicable rim, filled with a specified internal pressure, and a maximum load is applied. Exists in the half region on the grounding end TE side.

  Here, the applicable rim is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARD MANUAL, in the United States, refers to a rim defined by TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc. The specified internal pressure refers to the internal pressure (maximum air pressure) specified in accordance with the tire maximum load capacity of the standard such as JATMA when the tire is mounted on the applicable rim, and the maximum load load is The maximum mass allowed to be applied to the tire in the above standards. Furthermore, the ground contact end of the tread portion means a ground contact end portion in the tire width direction of the tire when the tire is mounted on the applicable rim, filled with a specified internal pressure, and a maximum load load is applied.

  Further, in the present invention, the groove width of each groove refers to the outer surface of the tire in a cross section perpendicular to the extending direction of each groove when the tire is mounted on an applicable rim, filled with a specified internal pressure, and no load is applied. The opening width.

  In the tire of the present invention, a plurality of recesses 3 recessed toward the inner surface of the tire are provided on the surface of the buttress portion 102 along the tire circumferential direction. Thus, by providing the recess 3 in the tire circumferential direction in the buttress portion 102, the contact frequency between the projection on the road surface and the buttress portion surface is reduced as compared with the case where the recess 3 is not provided. As a result, it is possible to obtain an effect of reducing road noise.

FIG. 2A shows a partially enlarged view of the recess forming region and FIG. 2B a partial cross-sectional view. As shown in the figure, in the present invention, the bottom 3 </ b> A having the deepest depth among the recesses 3 is located at the outer edge of the recesses 3. Here, the bottom 3A is positioned at the outer edge of the recess 3 as shown in FIG. 2B. The bottom 3A has a depth substantially perpendicular to the tire surface along the contour of the recess 3. It means that it exists on the perpendicular line. Further, as shown in the figure, the depth of the concave portion 3 gradually changes deeply from the surface of the buttress portion 102 to the bottom portion 3A, and the circumferential length L _{3A of} the bottom portion 3A is the circumferential length of the concave portion 3. It is smaller than the maximum value L ₃ of. In the example shown in FIGS. 1 and 2, the circumferential length L _3A of the bottom _3A is substantially zero.

  The area extending from the buttress part to the side part arranged on the inner side in the tire radial direction is a place where the deflection deformation is relatively large due to the distortion generated when the tire travels, and when the distortion locally occurs, It becomes a factor which a crack generate | occur | produces. In addition, if there are continuous portions where cracks are likely to occur, it will cause cracks that connect the portions. In particular, since the buttress portion bends in the tire radial direction, cracks tend to occur if a portion where cracks are likely to occur extends in the tire circumferential direction. On the other hand, in the present invention, since the depth of the recess 3 gradually changes from one outer edge toward the other outer edge, the rigidity step is reduced, so that the possibility of occurrence of cracks can be reduced. Further, in the present invention, since the circumferential length of the bottom 3A having the deepest depth is shorter than the maximum value of the circumferential length of the recess 3, it is possible to effectively suppress the occurrence of cracks. In addition to being able to do so, cracks do not extend in the tire circumferential direction because the recesses 3 are intermittently arranged in the tire circumferential direction. Furthermore, in the present invention, since the bottom 3A where distortion tends to concentrate is located at the outer edge of the recess 3, even if a minute crack is generated there, it is difficult to notice and difficult to visually confirm. Will not be damaged. Furthermore, since the rigidity of the buttress portion can be kept high as compared with the case where the entire concave portion 3 is deepened, it is possible to minimize the adverse effect on the steering stability while improving the road noise. Furthermore, since the recess 3 has a gradually changing depth, it is possible to suppress the occurrence of stone biting or the like in the recess 3.

  In the illustrated example, the recess 3 is formed so that the planar shape is an isosceles triangle, and the apex is on one side in the tire radial direction so that the apex of the isosceles triangle has a bottom portion 3A that has the deepest depth. It is arranged to be located in. In the present invention, as long as the above conditions are satisfied, the planar shape of the recess 3 is not limited to the illustrated shape, and may be any shape such as a triangular shape other than an isosceles triangle, a trapezoidal shape, or a semicircular shape. There may be. Moreover, there is no restriction | limiting in particular also about the direction of the arrangement | sequence of the recessed part 3. FIG.

  FIG. 3 shows a cross-sectional view of another specific example of the recess 3. In FIG. 3, the arrow direction coincides with the tire circumferential direction. FIG. 4 is a cross-sectional view of another specific example of the recess 3 shown in FIG. For example, in the case of the trapezoidal concave portion 3 as shown in FIG. 3A, the bottom portion 3A has a bottom portion of the bottom side and has a bottom portion 3A in the tire width direction from the bottom to the top. The depth can be increased (see FIG. 4A). Further, in the case of the semicircular recess 3 as shown in FIG. 3B, it has a bottom 3A at the midpoint of the arc, and has a depth in the tire width direction from the straight line portion toward the midpoint of the arc. Can be formed deeper (see FIG. 4B). Further, FIG. 3C is an example in which the isosceles triangular recesses 3 are arranged so that the height direction of the isosceles triangle coincides with the tire circumferential direction. In this case, the bottom portion is formed at the apex forming one end of the bottom side. 3A and can be formed so that the depth increases in a direction inclined from the side facing the apex serving as the bottom 3A toward the apex toward the apex (see FIG. 4C). In this case, it is also possible to have a bottom 3A 'at the apex of the isosceles triangle so that the depth increases in the tire circumferential direction from the base toward the apex (see FIG. 4D).

  In the present invention, the depth of the recess 3 may vary along the tire radial direction as shown in FIG. 2 and FIGS. 3 (a) and 3 (b), as shown in FIG. 3 (c). Moreover, you may change along the direction which inclines with respect to a tire circumferential direction or a tire circumferential direction. Preferably, as shown in FIG. 2 and the like, it is assumed that the depth of the concave portion 3 gradually changes deeply along the tire radial direction from the surface of the buttress portion 102 to the bottom portion 3A. In this way, the depth of the recess 3 is changed along the tire radial direction, that is, the bottom 3A where the depth of the recess 3 is the deepest is present at one end in the tire radial direction. Even during long-term use, the strain concentrates on the portion of the recess 3 having a short circumferential length at one end in the tire radial direction. Thereby, even when a crack occurs in one place, the risk of a crack being continuously generated in the tire circumferential direction is reduced, and deterioration in appearance can be more effectively suppressed.

  Further, as shown in the figure, it is assumed that the circumferential length of the concave portion 3 gradually decreases from the surface of the buttress portion 102 toward the bottom portion 3A. By gradually changing the circumferential length of the recess 3, strain concentration can be suppressed.

  In the present invention, since the circumferential length of the bottom 3A is relatively short with respect to the maximum value of the circumferential length of the recess, the corner is formed by a straight line or a curve in the bottom 3A. The angle θ between the corners is preferably a right angle or an obtuse angle, that is, 90 ° or more, and more preferably 150 ° or less. By setting the included angle of the corner portion formed in the bottom portion 3A having the deepest and shortest circumferential length to 90 ° or more, the stress concentration in the corner portion can be relaxed. Compared to the case of an acute angle, it is more effective in suppressing the occurrence of cracks in the bottom 3A. Here, the included angle of the corner is an angle formed by two straight lines forming the corner when the corner is a straight line, for example, as shown in FIGS. 2 (a) and 3 (c). In the case of the triangular recess 3, the angles α and γ (γ ′) of the apex where the bottom 3 A is located. In the case of the trapezoidal recess 3 as shown in FIG. This is an angle β formed by the sides on both sides of the upper base. In the case where the corner is a curved line, the angle is sandwiched between the tangents at the both-side contact points of the curved line existing at the apex position of the corner, and in the case of the semicircular recess 3 as shown in FIG. Is 180 °. As shown in the figure, when the concave portion 3 has any shape, the corner portion thereof is substantially formed in an R shape in order to alleviate strain concentration.

  The depth of the bottom 3A is preferably in the range of 0.5 mm to 1.5 mm, although it depends on the tire size. Generation | occurrence | production of a crack can be suppressed more reliably by making the maximum depth of the recessed part 3 1.5 mm or less. On the other hand, the reduction effect of road noise can be more reliably acquired by making the maximum depth of the recessed part 3 into 0.5 mm or more.

  About the circumferential direction length of the recessed part 3, the maximum value is outermost among the land parts 2a-2e divided by the several circumferential groove | channels 1a-1d in the ground surface of the tread part 101, and the recessed part 3 It is preferable that the land portion 3e adjacent to the provided buttress portion 102 has a lug groove and / or sipe disposed in the tire width direction, which is equal to or less than a circumferential distance between the sipe 4 and 5 in the illustrated example. By setting the circumferential length of the recess 3 to be equal to or less than the lug groove and / or the sipe circumferential interval existing in the vicinity thereof, the strain itself applied to the entire recess 3 is reduced, thereby further suppressing the generation of cracks. It becomes possible to do.

  As shown in the drawing, it is preferable that a plurality of the recesses 3 are provided not only in the tire circumferential direction but also in the tire radial direction. By reducing the size of the recesses 3 with a smaller size in each of the tire circumferential direction and the tire radial direction, the same road noise reduction effect as when a large number of the large recesses 3 are provided is provided. While obtaining the local rigidity, it is possible to maintain the uniformity of rigidity of the buttress portion 102 as a whole, and to further suppress the concentration of strain. For example, the recesses 3 can be provided in 1 to 3 rows in the tire radial direction, and preferably in 3 rows in the tire radial direction as illustrated. If the recesses 3 are provided in four or more rows in the tire radial direction, the rigidity may be lowered too much, and the locations where the strain concentrates are too close to each other, which is not preferable.

  Moreover, as shown in the drawing, the recesses 3 are preferably arranged so as to be offset from each other in the tire radial direction between the recesses 3 adjacent in the tire circumferential direction. In this way, the recesses 3 are sequentially offset in the tire radial direction in the tire radial direction, that is, by shifting the position in the tire radial direction, the rigidity of the buttress portion 102 as a whole decreases in the specific tire circumferential position. Can be suppressed. Thereby, it can suppress more effectively that a crack is connected between the recessed parts 3. FIG.

  Further, as shown in the figure, in the present invention, as described above, the depth of the recess 3 is changed along the tire radial direction from the surface of the buttress portion 102 to the bottom 3A, and the recess 3 is changed in the tire circumferential direction. It is preferable that the concave portions 3 adjacent to each other are arranged so that the direction of change in depth is opposite. As a result, the rigidity balance in the entire buttress portion 102 can be made uniform, and the concentration of strain can be further suppressed, and the occurrence of cracks can be further effectively suppressed.

  Furthermore, in this invention, it is preferable that the position in the tire radial direction of bottom part 3A differs between the recessed parts 3 adjacent to a tire circumferential direction. If the position of the bottom portion 3A in the tire radial direction is the same, there is a concern that the bottom portions 3A of the recesses 3 may be connected to each other and cracked even if the recesses 3 are spaced apart during long-term use. Even when the recess 3 is used over a long period of time by arranging the recess 3 so that the position of the bottom 3A in the tire circumferential direction is sequentially shifted in the tire radial direction, It can be suppressed that cracks are connected.

  In the tire according to the present invention, only the point that the buttress portion 102 is provided with the concave portion 3 as described above is important, and thereby the desired effect of the present invention can be obtained. As shown in the figure, the recess 3 according to the present invention may be disposed on the inner side of the vehicle mounting of the pair of left and right buttresses 102, which is less rigid than the outer side of the vehicle mounting and has low rigidity and easily causes tire vibration. Although it is preferable, it can also be arranged outside the vehicle and may be arranged on the buttress portions on both sides.

  In the illustrated tire, a sipe 6 that is inclined with respect to the tire circumferential direction is provided on the land portion 2c located on the tire equatorial plane CL. If the land portion is a rib shape that continues in the tire circumferential direction, the contact pressure increases. Therefore, by providing a sipe 6 on the land portion 2c and dividing the land portion 2c into a substantially block shape, the contact pressure is reduced. Can be made. Thereby, the rigidity of the land portion 2c can be optimized and the wear performance can be improved. Moreover, the effect which suppresses deterioration of riding comfort and a tire noise can also be acquired by reducing block rigidity moderately.

  In addition, the land portion 2b located on the outer side of the vehicle with respect to the land portion 2c includes a sub-groove 7 that ends at both ends in the land portion, and a thin line extending from one end of the sub-groove 7 and communicating with the circumferential grooves 1a and 1b. A so-called Helmholtz resonator 9 including grooves 8a and 8b is disposed. Here, the narrow grooves 8a and 8b refer to portions of the Helmholtz resonator 9 having a groove width of 1 mm or less, and the sub-groove 7 is formed to have a larger volume than the narrow grooves 8a and 8b. . Thereby, air column resonance can be reduced about circumferential direction grooves 1a and 1b, and a silence effect can be acquired. In addition, it is preferable that the bottom face of the sub-groove 7 is gradually shallower to the land surface at the end that terminates in the land 2b.

  Since the land portion 2b is substantially divided into blocks by the Helmholtz resonator 9, it is possible to appropriately reduce the ground pressure, optimize the rigidity, and improve the wear performance. Moreover, the effect which suppresses deterioration of riding comfort and a tire noise can also be acquired by reducing block rigidity moderately.

  On the other hand, the land portion 2d located on the inner side of the vehicle with respect to the land portion 2c is connected to the sub-groove 10 whose both ends terminate in the land portion and the circumferential grooves 1c and 1d extending from both ends of the sub-groove 10, respectively. A Helmholtz resonator 12 including narrow grooves 11a and 11b is disposed. Here, the narrow grooves 11a and 11b refer to portions of the Helmholtz resonator 12 having a groove width of 1 mm or less, and the sub-groove 10 is formed to have a larger volume than the narrow grooves 11a and 11b. . Thereby, air column resonance can be reduced about the circumferential grooves 1c and 1d, and a quiet effect can be obtained. In addition, it is preferable that the bottom face of the sub-groove 10 has a portion where the groove depth is shallower than the maximum groove depth at an intermediate portion in the tire circumferential direction. Since the auxiliary groove 10 constitutes a Helmholtz resonator 12 having a relatively long tire circumferential length, if the groove depth is increased for the entire groove, there is a possibility that the rigidity is locally lowered. By making the groove depth shallow at the intermediate part along the extending direction, it is possible to ensure the rigidity properly, which is preferable.

  Moreover, the sipe 13 extended from the circumferential groove | channel 1c and the sipe 14 extended from the circumferential groove | channel 1d are further arrange | positioned at the land part 2d. The land portion 2d is substantially divided into blocks by the Helmholtz resonator 12, but the Helmholtz resonator 12 disposed in the land portion 2d is more than the Helmholtz resonator 9 disposed in the land portion 2b. However, since the length along the tire circumferential direction is long, the sipe 13 and 14 is further arranged on the land portion 2d, and the land portion 2d is more finely divided into blocks so that the contact pressure is moderate. Reduction can be achieved. Thereby, also about the land part 2d, rigidity can be optimized and abrasion performance can be improved. Moreover, the effect which suppresses deterioration of riding comfort and a tire noise can also be acquired by reducing block rigidity moderately.

  Here, the specific structure of the Helmholtz resonators 9 and 12 in the present invention can be configured according to a known technique. For example, each of the secondary grooves 7 and 10 constituting the Helmholtz resonators 9 and 12 has a tire posture in which the tire is assembled to the applicable rim, filled with the highest air pressure, and loaded with a mass corresponding to the maximum load capacity. Underneath, the groove walls on both sides in the ground plane are formed to have a groove width that does not contact each other. Further, the auxiliary grooves 7 and 10 are arranged such that one or more sub-grooves are always completely included in the ground plane.

  Further, with respect to the sub-grooves 7 and 10, the extension length of the sub-groove portion within the ground plane is such that the groove width is 30% or more of the corresponding circumferential main groove width. It is preferable to be 40% or more of the extending length of the circumferential main groove. For each sub-groove, by providing a predetermined proportion of the groove width that is 30% or more of the corresponding groove width of the main groove in the circumferential direction, sufficient groove volume is secured and sufficient sound absorbing effect is exhibited. Can be a resonator. Here, the extending length of the groove means a length measured at the center in the width direction of the groove along the extending direction of the groove.

  Further, on the surface of the buttress portion 102 on the outer side of the vehicle, recesses 16 that are recessed toward the inner surface of the tire are provided along the tire circumferential direction. In the example shown in the drawing, the recess 16 has two rows in the tire width direction and extends along the tire circumferential direction, and the cross-sectional shape in the tire width direction has a semicircular shape that protrudes toward the tire inner surface side. . As described above, by arranging the concave portion 16 over the tire circumferential direction in the buttress portion 102, as in the case of the concave portion 3, compared with the case where the concave portion 16 is not provided, the projections on the road surface and the buttress portion surface are provided. And the occurrence of vibration caused by such contact can be suppressed, and as a result, a road noise reduction effect can be obtained. In addition to the improvement effect of road noise, the drainage effect in the tire circumferential direction can also be obtained by the semicircular shape of the concave streak 16 that protrudes toward the inner surface of the tire.

  The maximum depth of the concave stripe portion 16 is preferably in the range of 0.5 mm to 1.5 mm, although it depends on the tire size. By setting the maximum depth of the concave strip portion 16 to 1.5 mm or less, the occurrence of cracks can be more reliably suppressed. On the other hand, the reduction effect of road noise can be more reliably acquired by making the maximum depth of the concave-line part 16 into 0.5 mm or more.

  Further, a lug groove 17 extending from the concave strip portion 16 to the inside of the ground contact end TE of the tread portion 101 is disposed in the buttress portion 102 outside the vehicle. Furthermore, the sipe 18, 19 extending in the tire width direction is disposed on the outermost land portion 2a on which the concave stripe portion 16 is provided, and the sipe 18 is an inner side of the lug groove 17 in the tire width direction. It extends from the end to the circumferential groove 1a. Further, the sipe 19 is alternately arranged in the tire circumferential direction with the sipe 18, and in the buttress portion 102 extends from the outer end portion of the lug groove 17 in the tire width direction so as to be inclined with respect to the tire circumferential direction, and from the inclined portion. The tread portion 101 includes a width direction portion extending in the tire width direction to the inside of the ground contact end TE. Further, a sipe 20 extending in the tire circumferential direction is disposed in the land portion 2a in the vicinity of the circumferential groove 1a.

  Furthermore, in the illustrated example, the sipe 4, 5 extending in the tire width direction is disposed on the innermost land portion 2e provided with the recess 3 to the outside of the ground contact end TE of the tread portion 101. . Of these, the sipe 4 extends from the circumferential groove 1 d to the vicinity of the recess 3. The sipe 5 is alternately arranged in the tire circumferential direction with the sipe 4, and extends from the sipe 15 disposed in the tire circumferential direction in the vicinity of the circumferential groove 1d in the land portion 2e to the vicinity of the recess 3.

  Furthermore, the two circumferential grooves 1a and 1d arranged on the outer side in the tire width direction are provided with inclined surfaces in which the groove depth gradually decreases in the groove wall on the outer side in the tire width direction.

  In the tire of the present invention, the tire tread portion is not particularly limited except that the tread pattern is provided, and the details of the internal structure of the tire and the like are appropriately designed as desired according to conventional methods. Is possible.

Hereinafter, the present invention will be described in more detail with reference to examples.
The tire for passenger cars of the example which has a tread pattern as shown in FIG. 1 by tire size 215 / 55R17 was produced. In this tread pattern, the groove widths of the circumferential grooves 1a, 1b, 1c, and 1d were 9 mm, 8.8 mm, 6 mm, and 6 mm, respectively. As shown in FIGS. 2 (a) and 2 (b), the recesses 3 provided along the tire circumferential direction on the surface of the buttress portion on the inner side of the vehicle have an isosceles triangular shape and a depth of It was formed so that the deepest bottom was located at the apex of an isosceles triangle. Further, the depth of the concave portion 3 gradually changes deeply along the tire radial direction from the base of the isosceles triangle located on the surface of the buttress portion toward the apex of the isosceles triangle corresponding to the bottom. Its maximum depth was 0.7 mm. Furthermore, the included angle α at the corner formed at the bottom of the recess 3 was 115 °. Furthermore, the maximum value of the circumferential length of the recess 3 was equal to or less than the circumferential distance between the sipes 4 and 5 arranged in the land portion 2e. Furthermore, the maximum depth of the concave strip portion 16 provided along the tire circumferential direction on the surface of the buttress portion outside the vehicle is 0.7 mm.

  As a comparative example, a tire similar to the example was manufactured except that the recess 3 was not disposed.

<Road noise performance>
Each test tire obtained is assembled on an applicable rim, filled with the regular internal pressure specified by JATMA, and loaded at the maximum load load, and the road when running at 60 km / h on an indoor drum tester. The sound pressure level of noise was measured. The results were evaluated as relative values when the value of the test tire of the comparative example was set to 100. The larger the value, the greater the road noise reduction effect and the better the road noise performance. The results are shown in the table below.

<Appearance>
Each test tire obtained was assembled to the applicable rim and filled with the regular internal pressure specified by JATMA, so that the buttress part in which the recess 16 was formed on the test vehicle was on the outside of the vehicle, that is, About the example, it mounted | wore so that the buttress part in which the recessed part 3 was formed might become vehicle mounting inner side. Each vehicle was traveled 10,000 km on a normal paved road, and the presence or absence of cracks or cracks in the buttress portion inside the vehicle was confirmed visually.

  As a result, in the test tire of the example provided with the recess 3, some cracks were observed in the vicinity of the bottom 3 </ b> A of the recess 3, but there was no portion that developed into a crack, and the appearance was impaired. It wasn't. On the other hand, no problem in appearance occurred in the test tire of the comparative example in which the recess 3 was not provided.

  From the above, it was confirmed that in the tire according to the example in which the predetermined recess 3 is provided in the buttress portion, it is possible to suppress the deterioration of the appearance while reducing the road noise.

1a-1d Circumferential groove 2a-2e Land part 3 Recess 3A Bottom part 4, 5, 6, 13, 14, 15, 18, 19, 20 Sipe 7, 10 Sub groove 8a, 8b, 11a, 11b Narrow groove 9, 12 Helmholtz type resonator 16 concave streak part 17 lug groove 101 tread part 102 buttress part

Claims (7)

In a tire provided with a tread portion that is in contact with a road surface, and a buttress portion provided on the outer side in the tire width direction of the tread portion,
A plurality of recesses recessed toward the inner surface of the tire are provided on the surface of the buttress portion along the tire circumferential direction, and the bottom portion having the deepest depth is located at the outer edge of the recess, depth gradually deeply changed from the surface of the buttress portion to the bottom portion, the circumferential length of the bottom, rather smaller than the maximum value of the circumferential length of the recess, the circumferential length of the recess However, the depth gradually changes from the shallowest position to the deepest position of the recess along the tire surface, and a corner is formed by a straight line or a curve at the bottom. A tire characterized in that the included angle is a right angle or an obtuse angle . The recess each other, in a direction orthogonal to the tire circumferential direction along the tire surface, the tire according to claim 1, wherein are disposed offset from each other adjacent to each other in the tire circumferential direction. The depth of the concave portion is changed in a direction orthogonal to the tire circumferential direction along the tire surface , and the concave portions adjacent to each other in the tire circumferential direction are opposite in depth changing direction. The tire according to claim 1 or 2, which is arranged. The tire according to any one of claims 1 to 3 , wherein a depth of the bottom portion is within a range of 0.5 mm to 1.5 mm. The maximum value of the circumferential length of the concave portion is the outermost land portion partitioned by a plurality of circumferential grooves on the ground contact surface of the tread portion and is adjacent to the buttress portion provided with the concave portion. The tire according to any one of claims 1 to 4 , which is not more than a circumferential distance between lug grooves and / or sipes arranged in the tire width direction. The tire according to any one of claims 1 to 5 , wherein a plurality of the recesses are provided in a direction perpendicular to the tire circumferential direction along the tire surface . The tire according to any one of claims 1 to 6 , wherein, in the recesses adjacent to each other in the tire circumferential direction, positions of the bottom portions in a direction orthogonal to the tire circumferential direction along the tire surface are different.

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