tire

Abstract

To provide a tire having a meandering groove on a tread surface, capable of achieving improved drainage and suppression of an air column resonance sound while suppressing deterioration of braking performance.SOLUTION: In a tire, a meandering groove extending along a tire peripheral direction is formed on a tread surface. A groove width of the meandering groove in the tire peripheral direction changes in a predetermined repeated period, and Wmin / Wmax, which is a ratio of the maximum width and the minimum width of the groove width, is 0.35-0.85. A first groove wall and a second groove wall, which are both groove walls of the meandering groove, in a tread surface view, extend while meandering in a sine wave shape setting the predetermined repeated period as one period length, and in the tread surface view, a first sine wave shaped curve formed by the first groove wall and a second sine wave shaped curve formed by the second groove wall are arranged with a phase difference of 1 / 8 to 3 / 8 period in the tire peripheral direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] Conventionally, in pneumatic tires (hereinafter simply referred to as "tires"), various methods have been used to improve the drainage of water that has entered between the road surface and the tread surface in order to suppress hydroplaning. Patent Document 1 discloses a tire that can improve drainage while suppressing a decrease in braking performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-168222 Summary of the Invention [Problem to be solved by the invention]

[0004] In the tire disclosed in Patent Document 1, the main grooves as circumferential grooves extending along the tire circumferential direction have a predetermined shape. As a result, the tire disclosed in Patent Document 1 can improve drainage while suppressing a decrease in braking performance. However, even the circumferential grooves of the tire described in Patent Document 1 still have room for improvement in terms of further suppressing air column resonance noise.

[0005] An object of the present disclosure is to provide a tire having serpentine grooves on the tread surface that can improve drainage and suppress air column resonance noise while suppressing a decrease in braking performance. [Means for solving the problem]

[0006] As a first aspect of the present disclosure, a tire has a meandering groove formed along the tire circumferential direction on the tread surface. The groove width of the meandering groove in the tire width direction changes at a predetermined repetition period along the tire circumferential direction. When the maximum width of the groove width is Wmax and the minimum width of the groove width is Wmin, the ratio of the minimum width to the maximum width, Wmin / Wmax, is 0.35 to 0.85. The first groove wall and the second groove wall, which are both groove walls of the meandering groove, extend while meandering in a sine wave shape with the predetermined repetition period as one cycle length in a tread surface view. In the tread surface view, a first sine wave curve formed by the first groove wall and a second sine wave curve formed by the second groove wall are arranged with a phase difference of 1 / 8 to 3 / 8 cycle in the tire circumferential direction. With this configuration, a tire having a meandering groove capable of realizing improved drainage performance, suppression of air column resonance noise, and suppression of deterioration of braking performance on the tread surface can be realized.

[0007] As one embodiment of the present disclosure, the repetition period of the first sine wave curve and the second sine wave curve is 15 to 100 times the maximum amplitude in the tire width direction of the first sine wave curve and the second sine wave curve in the tread surface view. With this configuration, the drainage performance can be further improved.

[0008] As one embodiment of the present disclosure, three or more circumferential grooves extending along the tire circumferential direction are formed on the tread surface. Among the three or more circumferential grooves, one or more inner circumferential grooves located inside the tire width direction from the outer circumferential grooves located on the outermost sides on both sides in the tire width direction are constituted by the meandering groove. With this configuration, it becomes easy to promote the dispersion of resonance frequencies in a plurality of circumferential grooves, and it becomes easy to realize the reduction of the sound pressure peak of the entire circumferential groove.

[0009] As one embodiment of the present disclosure, the outer circumferential groove extends linearly along the tire circumferential direction in a tread surface view. By adopting this configuration, the influence of the axial force fluctuation can be reduced.

[0010] As one embodiment of the present disclosure, among the one or more inner circumferential grooves, the inner circumferential groove adjacent to the outer circumferential groove is constituted by the meandering groove, and the land portion partitioned from each other by the outer circumferential groove and the inner circumferential groove adjacent to the outer circumferential groove and constituted by the meandering groove is provided with a resonator. The resonator includes an air chamber opened to the tread surface of the land portion and one or more outer constricted necks communicating the air chamber with the outer circumferential groove. The resonator does not include an inner constricted neck communicating the air chamber with the inner circumferential groove adjacent to the outer circumferential groove and constituted by the meandering groove. By adopting this configuration, the resonator can reduce the sound pressure peak of the air column resonance sound in the outer circumferential groove, and can suppress the deterioration of the braking performance of the tire as compared with the configuration including the inner constricted neck.

[0011] As one embodiment of the present disclosure, in the shoulder land portion partitioned from each other by the outer circumferential groove and the tread end of the tread surface, a width direction groove opening to the outer circumferential groove is formed at a position overlapping with the extension line of the outer constricted neck provided in the land portion. By adopting this configuration, both drainage performance and appearance design can be achieved.

[0012] As one embodiment of the present disclosure, the one or more inner circumferential grooves include two inner circumferential grooves partitioning a central land portion intersecting with the tire equatorial plane from each other, and a resonator including an air chamber opened to the tread surface and a constricted neck communicating the air chamber with at least one of the two inner circumferential grooves is not provided in the central land portion. By adopting this configuration, the reduction of the rigidity of the central land portion located at the center in the tire width direction of the tread surface can be suppressed.

[0013] As one embodiment of the present disclosure, the one or more inner circumferential grooves include two or more inner circumferential grooves formed by the meandering grooves, and the tire circumferential repetition period of one inner circumferential groove formed by the meandering groove is different from that of another inner circumferential groove formed by the meandering groove in the tire circumferential direction. With this configuration, excessive fluctuations in the compression rigidity in the tire circumferential direction can be suppressed.

Effects of the Invention

[0014] According to the present disclosure, it is possible to provide a tire having meandering grooves on the tread surface that can improve drainage performance, suppress air column resonance noise, and suppress a decrease in braking performance.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the tire according to the present disclosure will be exemplarily described with reference to the drawings. The same reference numerals are assigned to the common configurations in each figure. In this specification, the tire width direction refers to the direction parallel to the rotation axis of the tire. The tire radial direction refers to the direction orthogonal to the rotation axis of the tire and in the radial direction centered on the rotation axis. The tire circumferential direction refers to the direction in which the tire rotates around the rotation axis of the tire.

[0017] In this specification, the "tread surface" means the outer peripheral surface extending over the entire circumference of the tire that comes into contact with the road surface when a tire assembled to a rim and filled with a specified internal pressure is rolled in a state of bearing the maximum load (hereinafter also referred to as the "maximum load state"). Further, the "tread edge" means the outer edge in the tire width direction of the tread surface.

[0018] In this specification, the "rim" refers to the standard rim (Measuring Rim in the ETRTO's STANDARDS MANUAL, Design Rim in the TRA's YEAR BOOK) in the applicable size described in or to be described in the industrial standards effective in the region where the tire is produced and used, such as the JATMA YEAR BOOK of JATMA (Japan Automobile Tire Association) in Japan, the STANDARDS MANUAL of ETRTO (The European Tyre and Rim Technical Organisation) in Europe, and the YEAR BOOK of TRA (The Tire and Rim Association, Inc.) in the United States. In the case of a size not described in the above industrial standards, it refers to a rim having a width corresponding to the bead width of the tire. The "rim" includes sizes that may be included in the above industrial standards in the future in addition to the current sizes. Examples of "sizes to be described in the future" include the sizes described as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO's STANDARDS MANUAL.

[0019] In this specification, the "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating described in industrial standards such as the JATMA YEAR BOOK. In the case of a size not described in the above industrial standards, it refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Further, in this specification, the "maximum load" refers to the load corresponding to the maximum load capacity of a tire of the applicable size described in the above industrial standards. In the case of a size not described in the above industrial standards, it refers to the load corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted.

[0020] Hereinafter, as an embodiment of a tire according to the present disclosure, a pneumatic tire 1 (hereinafter simply referred to as "tire 1") will be exemplarily described with reference to the drawings. In this embodiment, a radial tire for a passenger car will be exemplarily described as tire 1, but other types of tires may also be used.

[0021] FIG. 1 is a cross-sectional view of tire 1 in the tire width direction. As shown in FIG. 1, tire 1 includes a pair of bead portions 11, a pair of sidewall portions 12, and a tread portion 13. The sidewall portion 12 is continuous with the outside of the bead portion 11 in the tire radial direction A. The tread portion 13 is continuous with the pair of sidewall portions 12. Both ends of the tread portion 13 in the tire width direction B are respectively continuous with the sidewall portions 12.

[0022] Each bead part 11 includes a bead core 11a and a bead filler 11b disposed outside the bead core 11a in the tire radial direction A. The tire 1 includes a carcass 14 straddling between a pair of bead cores 11a. The carcass 14 is composed of a carcass ply in which cords made of organic fiber or steel are arranged. Further, the tire 1 includes a belt 15 disposed outside the crown part of the carcass 14 in the tire radial direction A. The belt 15 is composed of a belt ply in which cords made of organic fiber or steel are arranged. The belt ply constituting the belt 15 may include an inclined belt layer in which the cords are inclined by 10° or more with respect to the tire circumferential direction C. Also, the belt ply constituting the belt 15 may include a circumferential belt layer in which the cords extend along the tire circumferential direction C. Here, the phrase "the cords extend along the tire circumferential direction" means that the inclination angle of the cords with respect to the tire circumferential direction C is 0° or more and less than 10°. Further, the belt 15 may include a plurality of belt plies laminated in the tire radial direction A, each including at least one layer of the above-described inclined belt layer and circumferential belt layer.

[0023] Also, the tire 1 includes a tread rubber 7 disposed outside the belt 15 in the tire radial direction A and a side rubber 8 disposed outside the side part of the carcass 14 in the tire width direction B. Further, the tire 1 includes an inner liner 16 laminated on the inner surface of the carcass 14.

[0024] The tire 1 of the present embodiment has the above-described internal structure, but the internal structure is not particularly limited. Therefore, the tire 1 may have other internal structures.

[0025] FIG. 2 is a developed view showing a part of the tread surface T of the tread portion 13 of the tire 1 of the present embodiment shown in FIG. 1. As shown in FIG. 2, circumferential grooves 21 to 24 extending along the tire circumferential direction C are formed in the tread surface T of the present embodiment. These circumferential grooves 21 to 24 are endless annular grooves in the tire circumferential direction C. The four circumferential grooves 21 to 24 of the present embodiment are composed of two outer circumferential grooves 21 and 24 located on the outermost sides on both sides in the tire width direction B, and two inner circumferential grooves 22 and 23 located inside the two outer circumferential grooves 21 and 24 in the tire width direction B. Here, the inner side in the tire width direction B means the side approaching the tire equatorial plane CL in the tire width direction B. The outer side in the tire width direction B is the opposite side to the inner side in the tire width direction B, and means the side moving away from the tire equatorial plane CL in the tire width direction B.

[0026] As shown in FIG. 2, five land portions 31 to 35 partitioned by the above-described four circumferential grooves 21 to 24 and the tread ends TE on both sides in the tire width direction B are formed on the tread surface T of the tire 1 of the present embodiment. The five land portions 31 to 35 are composed of one central land portion 33, two intermediate land portions 32 and 34, and two shoulder land portions 31 and 35. Both the "central land portion" and the "intermediate land portion" are land portions located between the two outer circumferential grooves located on the outermost sides on both sides in the tire width direction B, and mean land portions partitioned between two adjacent circumferential grooves in the tire width direction B. However, the "central land portion" is a land portion provided at a position intersecting the tire equatorial plane CL, while the "intermediate land portion" is a land portion provided at a position not intersecting the tire equatorial plane CL. Hereinafter, for convenience of explanation, when the central land portion 33 and the intermediate land portions 32 and 34 are not particularly distinguished, they are simply described as "inner land portions 32 to 34". The "shoulder land portion" is a land portion partitioned between the tread end TE and the circumferential groove located on the outermost side in the tire width direction.

[0027] More specifically, the central land portion 33 of the present embodiment is partitioned between the two inner circumferential grooves 22 and 23. Also, one intermediate land portion 32 of the present embodiment is located on one side in the tire width direction B (left side in FIG. 2) with the tire equatorial plane CL interposed therebetween, and is partitioned between the outer circumferential groove 21 and the inner circumferential groove 22. The other intermediate land portion 34 of the present embodiment is located on the other side in the tire width direction B (right side in FIG. 2) with the tire equatorial plane CL interposed therebetween, and is partitioned between the outer circumferential groove 24 and the inner circumferential groove 23. Each of the inner land portions 32 to 34 of the present embodiment is constituted by a rib-shaped land portion that is continuous over the entire tire circumferential direction C without being divided in the tire circumferential direction C.

[0028] Furthermore, one shoulder land portion 31 is located on one side in the tire width direction B (left side in FIG. 2) with the tire equatorial plane CL interposed therebetween, and is partitioned between the tread edge TE and the outer circumferential groove 21. The other shoulder land portion 35 is located on the other side in the tire width direction B (right side in FIG. 2) with the tire equatorial plane CL interposed therebetween, and is partitioned between the tread edge TE and the outer circumferential groove 24.

[0029] Although details will be described later, as shown in FIG. 2, resonators 70 including air chambers 71 and outer constriction necks 72 are disposed in each of the two intermediate land portions 32 and 34 of the present embodiment. A plurality of resonators 70 are provided in each of the intermediate land portions 32 and 34 at predetermined intervals along the tire circumferential direction C.

[0030] Also, as shown in FIG. 2, a plurality of width direction grooves 40 are formed in each of the two shoulder land portions 31 and 35 of the present embodiment. The width direction grooves 40 are not limited to grooves parallel to the tire width direction B, and may be grooves inclined at an angle equal to or less than a predetermined angle (for example, 30° or less) with respect to the tire width direction B. In each of the two shoulder land portions 31 and 35, the plurality of width direction grooves 40 are arranged at predetermined intervals in the tire circumferential direction C. The width direction grooves 40 extend over the entire tire width direction B of each of the shoulder land portions 31 and 35. Thus, each of the shoulder land portions 31 and 35 is constituted by a plurality of block land portions partitioned in the tire circumferential direction C by the width direction grooves 40.

[0031] The width-direction groove 40 formed in one shoulder land portion 31 extends from the tread edge TE to the outer circumferential groove 21. Further, the width-direction groove 40 formed in the other shoulder land portion 35 extends from the tread edge TE to the outer circumferential groove 24.

[0032] More specifically, the outer ends in the tire width direction B of the width-direction grooves 40 formed in the shoulder land portions 31 and 35 extend to the tread edge TE. In particular, in the present embodiment, the outer ends in the tire width direction B of the width-direction grooves 40 extend beyond the tread edge TE to a position outside the tread edge TE in the tire width direction B. Further, the inner ends in the tire width direction B of the width-direction grooves 40 formed in the shoulder land portions 31 and 35 are open to the outer circumferential grooves 21 and 24. That is, the width-direction groove 40 formed in the shoulder land portion 31 is continuous with the outer circumferential groove 21 inside the tire width direction B. Also, the width-direction groove 40 formed in the shoulder land portion 35 is continuous with the outer circumferential groove 24 inside the tire width direction B.

[0033] Four circumferential grooves 21 to 24 are formed in the tread surface T of the tire 1 of the present embodiment, but the present invention is not limited to this configuration. The tire 1 may be provided with one or more circumferential grooves on the tread surface T. That is, the number of circumferential grooves formed in the tread surface T of the tire 1 is not particularly limited as long as it is one or more. Therefore, the land portions formed in the tread surface T of the tire 1 are not limited to the five land portions 31 to 35 of the present embodiment. That is, the tread surface T of the tire 1 may be provided with two or more land portions partitioned by one or more circumferential grooves and the tread edges on both sides in the tire width direction B.

[0034] Also, the configuration of each land portion of the tire 1 is not limited to the configuration of the present embodiment. In the shoulder land portions 31 and 35 of the present embodiment, the width-direction grooves 40 are provided, but a configuration in which the width-direction grooves 40 are not provided may also be used. Further, the width-direction grooves 40 do not necessarily cross each of the shoulder land portions 31 and 35 in the tire width direction B. That is, one end or both ends of the extending direction of the width-direction grooves 40 may terminate within each of the shoulder land portions 31 and 35.

[0035] Furthermore, resonators 70 are provided in each of the intermediate land portions 32 and 34 of the present embodiment, but a configuration in which the resonators 70 are not provided may also be used. Also, the resonator 70 may be provided in either of the intermediate land portions 32 and 34. For example, the resonator 70 may be provided only in one of the intermediate land portions 32 and 34 that becomes the inner side (vehicle side) when the tire 1 is mounted on the vehicle. In this way, it becomes easier to ensure the rigidity during cornering with respect to the other of the intermediate land portions 32 and 34 that becomes the outer side (opposite side to the vehicle side) when the tire 1 is mounted on the vehicle. Furthermore, the resonator 70 may be provided in the central land portion 33 or may be provided in the shoulder land portions 31 and 35.

[0036] Hereinafter, with reference to FIGS. 2 and 3, the meandering grooves 20 formed in the tread surface T will be described. In the present embodiment, the two inner circumferential direction grooves 22 and 23 of the tread surface T are constituted by the meandering grooves 20. FIG. 3 is an enlarged view of the inner circumferential direction groove 22 as the meandering groove 20 shown in FIG. 2, but the configuration of the inner circumferential direction groove 23 as the meandering groove 20 is the same as that of the inner circumferential direction groove 22. Hereinafter, when the two inner circumferential direction grooves 22 and 23 are not particularly distinguished, they will be simply referred to as "meandering grooves 20".

[0037] As shown in FIGS. 2 and 3, the meandering groove 20 extends along the tire circumferential direction C on the tread surface T. More specifically, the first groove wall 20a and the second groove wall 20b, which are both groove walls of the meandering groove 20, extend while meandering in a sine wave shape with a predetermined repetition period λ (see FIG. 3) along the tire circumferential direction C as one cycle length in the tread surface view (see FIGS. 2 and 3) which is a front view of the tread surface T. Therefore, as shown in FIG. 3, the first groove wall 20a and the second groove wall 20b have an amplitude A along the tire width direction B. Although details will be described later, in the tread surface view, the first sine wave curve formed by the first groove wall 20a of the meandering groove 20 has a phase difference in the tire circumferential direction C from the second sine wave curve formed by the second groove wall 20b of the meandering groove 20. Further, the groove bottom 20c of the meandering groove 20 is constituted by a flat surface extending along the tire circumferential direction C. Here, the "sine wave shape" as used herein does not refer only to a perfect sine wave, but includes a substantial sine wave. In this specification, a substantial sine wave refers to one in which the variation with respect to the sine wave obtained as an approximate curve is within a range of ±5% or less. The sine wave as an approximate curve can be, for example, a sine wave approximated using the least squares method with respect to a curve obtained by tracing the groove wall in the tread surface view.

[0038] As shown in FIG. 3, the meandering groove 20 has a groove width W that varies with a predetermined repetition period λ along the tire circumferential direction C. This predetermined repetition period λ is the same as the above-described repetition period λ of the first groove wall 20a and the second groove wall 20b of the meandering groove 20 that extends in a sine wave shape in the tread surface view. Further, the groove width W of the meandering groove 20 means the distance in the tire width direction B between the first groove wall 20a and the second groove wall 20b. Thus, the meandering groove 20 includes a wide portion 51a and a narrow portion 51b.

[0039] The wide portion 51a includes a portion where the groove width W becomes the maximum width Wmax. Further, the narrow portion 51b includes a portion where the groove width W becomes the minimum width Wmin. The wide portion 51a and the narrow portion 51b are alternately provided in the tire circumferential direction C.

[0040] Here, Wmin / Wmax, which is the ratio of the maximum width Wmax to the minimum width Wmin of the groove width W of the meandering groove 20, is 0.35 to 0.85. As an example, the maximum width Wmax of the groove width W in this embodiment is 9.447 mm. Also, the minimum width Wmin of the groove width W in this embodiment is 5.967 mm. Therefore, Wmin / Wmax, which is the ratio of the maximum width Wmax to the minimum width Wmin in this embodiment, is 0.632.

[0041] Thus, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 meander along the tire circumferential direction C in a tread surface view, and the groove width W of the meandering groove 20 changes with a predetermined repetition period λ along the tire circumferential direction C. Therefore, within the meandering groove 20, a water flow along the meandering of the first groove wall 20a and the second groove wall 20b is generated. That is, within the meandering groove 20, a water flow along the first groove wall 20a and the second groove wall 20b is generated.

[0042] More specifically, the water flowing in the meandering groove 20 flows into a narrow portion 51b including a portion where the groove width W of the meandering groove 20 becomes the minimum width Wmin after passing through a wide portion 51a including a portion where the groove width W of the meandering groove 20 becomes the maximum width Wmax. At this time, the water flowing in the meandering groove 20 flows along the first groove wall 20a and the second groove wall 20b as the groove width W of the meandering groove 20 decreases. As shown in FIG. 3, in a tread surface view, the extension line direction of the first groove wall 20a and the second groove wall 20b located on the way from the wide portion 51a to the narrow portion 51b (see the dashed-dotted arrow in FIG. 3) faces outward in the tire width direction B of the meandering groove 20. Therefore, when the water flowing in the meandering groove 20 flows from the wide portion 51a into the narrow portion 51b, it is easily drained so as to jump out of the meandering groove 20 in the extension line direction of the first groove wall 20a and the second groove wall 20b. That is, the water flowing in the meandering groove 20 pulsates with a predetermined repetition period λ and is easily drained in the extension line direction of the first groove wall 20a and the second groove wall 20b when flowing from the wide portion 51a into the narrow portion 51b. Therefore, the drainage performance of the water that has entered between the road surface and the tread surface T can be improved.

[0043] Also, as described above, by setting Wmin / Wmax, which is the ratio of the maximum width Wmax to the minimum width Wmin of the groove width W of the meandering groove 20, to 0.35 to 0.85, compared to the case where Wmin / Wmax does not belong to the above range, the depression of the land portion (in this embodiment, the depression of the side walls of the inner land portions 32 to 34) formed by the first groove wall 20a and the second groove wall 20b that meander in a sine wave shape can suppress the decrease in the rigidity of the land portion (in this embodiment, the inner land portions 32 to 34). As a result, it is possible to suppress the decrease in the braking performance of the tire 1.

[0044] Furthermore, by setting Wmin / Wmax within the above range, the above-described improvement in drainage performance can be obtained more reliably. That is, when the value of Wmin / Wmax is less than 0.35, the flow of water along the first groove wall 20a and the second groove wall 20b at the narrow portion 51b and the flow of water along the tire circumferential direction C are likely to concentrate excessively, and the degree of improvement in drainage performance may be small. Also, when the value of Wmin / Wmax is greater than 0.85, the water in the meandering groove 20 becomes less likely to pulsate, and the degree of improvement in drainage performance may be small.

[0045] Also, as shown in FIGS. 2 and 3, in a tread surface view, the first sine wave curve formed by the first groove wall 20a of the meandering groove 20 and the second sine wave curve formed by the second groove wall 20b of the meandering groove 20 are arranged with a phase difference of 1 / 8 to 3 / 8 cycles in the tire circumferential direction C. By providing such a phase difference, compared to a configuration outside the above range of the phase difference, it is possible to suppress the column resonance sound that can be generated by the meandering groove 20. Note that the "phase difference of 1 / 8 to 3 / 8 cycles in the tire circumferential direction C" means that there is a phase difference of 1 / 8 to 3 / 8 cycles in any one direction of the tire circumferential direction C. The phase difference in the present embodiment shown in FIGS. 2 and 3 is 1 / 4 cycle.

[0046] FIG. 4 shows some of the sound waves traveling in the meandering groove 20 shown in FIGS. 2 and 3 by dashed arrows L1 and L2. As shown in FIG. 4, the sound wave represented by the dashed arrow L1 traveling in the meandering groove 20 enters the meandering groove 20 from one end side (the upper side in FIG. 4) in the tire circumferential direction C of the meandering groove 20, and is repeatedly reflected by the first groove wall 20a and the second groove wall 20b, and exits from the other end side (the lower side in FIG. 4) in the tire circumferential direction C of the meandering groove 20. On the other hand, the sound wave represented by the dashed arrow L2 traveling in the meandering groove 20 enters the meandering groove 20 from one end side (the upper side in FIG. 4) in the tire circumferential direction C of the meandering groove 20, and by repeatedly reflecting by the first groove wall 20a and the second groove wall 20b, returns to one end side (the upper side in FIG. 4) in the tire circumferential direction C of the meandering groove 20. That is, the sound wave represented by the dashed arrow L2 traveling in the meandering groove 20 does not exit from the other end side (the lower side in FIG. 4) in the tire circumferential direction C of the meandering groove 20. The presence of the sound wave as shown by the dashed arrow L2 can suppress the column resonance sound generated through the meandering groove 20 as compared with the case where the sound wave as shown by the dashed arrow L2 does not exist.

[0047] FIG. 5 is a diagram showing meandering grooves 120 and 220 as comparative examples. Specifically, FIG. 5(a) shows a comparative example in which the phase difference in the tire circumferential direction C between the first groove wall 120a and the second groove wall 120b is 1 / 2 cycle. FIG. 5(b) shows a comparative example in which there is no phase difference (the phase difference is 0 cycle) in the tire circumferential direction C between the first groove wall 220a and the second groove wall 220b. In FIG. 5(a), some of the sound waves traveling in the meandering groove 120 are shown by dashed arrows L3 and L4. In FIG. 5(b), some of the sound waves traveling in the meandering groove 220 are shown by dashed arrows L5 and L6. Note that in both of the meandering grooves 120 and 220 as comparative examples shown in FIGS. 5(a) and 5(b), Wmin / Wmax, which is the ratio of the maximum width Wmax to the minimum width Wmin, belongs to the range of 0.35 to 0.85.

[0048] As shown in Fig. 5(a), the sound waves represented by the dashed arrows L3 and L4 traveling in the meandering groove 120 as a comparative example enter the meandering groove 120 from one end side (the upper side in Fig. 5(a)) in the tire circumferential direction C of the meandering groove 120, are repeatedly reflected by the first groove wall 120a and the second groove wall 120b, and then escape from the other end side (the lower side in Fig. 5(a)) in the tire circumferential direction C of the meandering groove 120. Similarly, as shown in Fig. 5(b), the sound waves represented by the dashed arrows L5 and L6 traveling in the meandering groove 220 as a comparative example enter the meandering groove 220 from one end side (the upper side in Fig. 5(b)) in the tire circumferential direction C of the meandering groove 220, are repeatedly reflected by the first groove wall 220a and the second groove wall 220b, and then escape from the other end side (the lower side in Fig. 5(b)) in the tire circumferential direction C of the meandering groove 220. Therefore, with the phase difference provided on the groove walls of the meandering grooves 120 and 220 as comparative examples shown in Figs. 5(a) and 5(b), the sound waves easily escape from one side to the other side in the tire circumferential direction C.

[0049] From the above, for the groove width W that varies with a predetermined repetition period λ (see Fig. 3), by setting Wmin / Wmax in the range of 0.35 to 0.85 and setting the phase difference between the first groove wall 20a and the second groove wall 20b of the meandering groove 20 to be in the range of 1 / 8 to 3 / 8 of a cycle, it becomes easier to realize a sound wave that is reflected and returns without escaping from one side to the other side in the tire circumferential direction C as shown by the dashed arrow L2 in Fig. 4. Thereby, it is possible to realize the tire 1 having the meandering groove 20 capable of suppressing a decrease in braking performance while improving drainage performance and suppressing air column resonance sound.

[0050] Hereinafter, with reference to Figs. 2 to 4, further features of the tire 1 of the present embodiment will be described.

[0051] First, referring to FIG. 3, further features of one meandering groove 20 will be described. As shown in FIG. 3, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 of the present embodiment have an amplitude A along the tire width direction B. More specifically, the first sine wave-shaped curve formed by the first groove wall 20a in a tread surface view has an amplitude AP1 along the tire width direction B. Also, the second sine wave-shaped curve formed by the second groove wall 20b in a tread surface view has an amplitude AP2 along the tire width direction B. Here, in the present embodiment, the amplitude AP1 of the first sine wave-shaped curve and the amplitude AP2 of the second sine wave-shaped curve are equal. Therefore, in the present embodiment, the maximum amplitude in the tire width direction B of the first sine wave-shaped curve and the second sine wave-shaped curve in a tread surface view is the amplitude AP1 of the first sine wave-shaped curve or the amplitude AP2 of the second sine wave-shaped curve.

[0052] However, the amplitude AP1 of the first sine wave-shaped curve and the amplitude AP2 of the second sine wave-shaped curve may be different. In such a case, the maximum amplitude in the tire width direction B of the first sine wave-shaped curve and the second sine wave-shaped curve in a tread surface view means the larger amplitude of the amplitude AP1 of the first sine wave-shaped curve and the amplitude AP2 of the second sine wave-shaped curve.

[0053] Here, the repetition period λ (see FIG. 3) of the first sine wave-shaped curve and the second sine wave-shaped curve is preferably 15 to 100 times the maximum amplitude (amplitude AP1 or AP2 in the present embodiment) in the tire width direction B of the first sine wave-shaped curve and the second sine wave-shaped curve in a tread surface view. With such a configuration, when the water flowing in the meandering groove 20 flows from the wide portion 51a to the narrow portion 51b, it is more easily drained so as to jump out of the meandering groove 20 in the direction of the extension lines of the first groove wall 20a and the second groove wall 20b (see the dashed arrow in FIG. 3).

[0054] More specifically, by setting the repetition period λ to 15 times or more the maximum amplitude of the first sinusoidal curve and the second sinusoidal curve, it is possible to suppress the excessive concentration of the water flow along the first groove wall 20a and the second groove wall 20b in the narrow portion 51b and the water flow along the tire circumferential direction C. Therefore, the degree of improvement in drainage performance can be increased. Further, by setting the repetition period λ to 100 times or less the maximum amplitude of the first sinusoidal curve and the second sinusoidal curve, the water in the meandering groove 20 becomes more likely to pulsate, and the degree of improvement in drainage performance can be increased.

[0055] Also, when the tire is rolling, the contact length, which is the length in the tire circumferential direction C of the tread contact surface that contacts the road surface, is preferably 0.5 to 20 times the repetition period λ of the meandering groove 20. By the contact length being 0.5 times or more the repetition period λ of the meandering groove 20, the meandering groove 20 contacts a sufficient number of times along the tire circumferential direction C when the tire is rolling to pulsate. For this reason, the water flowing in the meandering groove 20 can be effectively drained to the outside of the meandering groove 20. Further, by the contact length being 20 times or less the repetition period λ of the meandering groove 20, a water flow along the first groove wall 20a and the second groove wall 20b is likely to occur in the meandering groove 20. For this reason, the water flowing in the meandering groove 20 can be effectively drained to the outside of the meandering groove 20.

[0056] Note that the groove depth D (see FIG. 1) of the meandering groove 20 is not particularly limited. The groove depth D of the meandering groove 20 of the present embodiment is 8 mm as an example, but it may be shallower or deeper than this.

[0057] Next, with reference to FIGS. 2 and 3, the arrangement of the meandering groove 20 on the tread surface T of the tire 1 will be described.

[0058] As shown in FIG. 2, on the tread surface T of the present embodiment, three or more (four in the present embodiment) circumferential grooves 21 to 24 extending along the tire circumferential direction C are formed. Among the three or more circumferential grooves 21 to 24, one or more (two in the present embodiment) inner circumferential grooves 22 and 23 located inside the tire width direction B from the outer circumferential grooves 21 and 24 located on the outermost sides on both sides in the tire width direction B are constituted by the meandering groove 20.

[0059] Thus, it is preferable that the inner circumferential grooves 22 and 23 located inside the tire width direction B from the outer circumferential grooves 21 and 24 are constituted by the meandering groove 20. The inner circumferential grooves 22 and 23 are more likely to have a longer extension length on the tread contact surface compared to the outer circumferential grooves 21 and 24. The resonance frequency f of the air column resonance sound is represented by the following (Equation 2). "l" is the extension length on the tread contact surface, "α" is the correction coefficient at the open end of the air column tube, "c" is the speed of sound, and "n" is a natural number.

[0060] f = nc / (2(l + α)) ······(Equation 1)

[0061] That is, in the inner circumferential grooves 22 and 23, the value of "l" in the above (Equation 1) is more likely to be larger compared to the outer circumferential grooves 21 and 24.

[0062] Furthermore, by constituting the inner circumferential grooves 22 and 23 with the meandering groove 20, the moving distance of the sound wave passing through the inner circumferential grooves 22 and 23 from one side to the other side in the tire circumferential direction C becomes longer. This is because the sound wave is repeatedly reflected by the first groove wall 20a and the second groove wall 20b in the meandering groove 20, and the moving distance of the sound wave is longer compared to the circumferential groove where the groove wall extends straight along the tire circumferential direction C. Therefore, by using the meandering groove 20, an effect similar to that of increasing the value of "l" in the above (Equation 1) can be obtained.

[0063] In short, the inner circumferential grooves 22 and 23 are more likely to have a longer extension length on the tread contact surface compared to the outer circumferential grooves 21 and 24. Therefore, in the inner circumferential grooves 22 and 23, the value of "l" in the above (Equation 1) is more likely to be larger than that in the outer circumferential grooves 21 and 24. Accordingly, based on the above (Equation 1), the resonance frequency f of the inner circumferential grooves 22 and 23 is more likely to be smaller than the resonance frequency f of the outer circumferential grooves 21 and 24. By forming such inner circumferential grooves 22 and 23 as the meandering grooves 20, as described above, the effect that the value of "l" in the above (Equation 1) becomes even larger can be obtained. That is, the resonance frequency f of the inner circumferential grooves 22 and 23 can be made even smaller. Therefore, the dispersion of the resonance frequencies in the plurality of circumferential grooves 21 to 24 is more likely to be promoted, and it is easier to reduce the sound pressure peak of the entire circumferential grooves 21 to 24.

[0064] In this embodiment, both of the two inner circumferential grooves 22 and 23 are constituted by the meandering grooves 20, but only one of them may be sufficient. However, among the inner circumferential grooves located between the two outer circumferential grooves 21 and 24, it is preferable to form the inner circumferential groove (both of the two inner circumferential grooves 22 and 23 in this embodiment) located most inward in the tire width direction B as the meandering groove 20, and it is more preferable to form all the inner circumferential grooves (only the two inner circumferential grooves 22 and 23 in this embodiment) by the meandering grooves 20. This is the same even when there are three or more inner circumferential grooves. By doing so, the dispersion of the resonance frequencies in the plurality of circumferential grooves 21 to 24 is more likely to be promoted, and it is easier to reduce the sound pressure peak of the entire circumferential grooves 21 to 24.

[0065] Further, as shown in FIG. 2, it is preferable that the outer circumferential grooves 21 and 24 extend linearly along the tire circumferential direction C in a tread surface view. Hereinafter, for convenience of explanation, in a tread surface view, a circumferential groove that extends linearly along the tire circumferential direction C is referred to as a "straight groove". By configuring the outer circumferential grooves 21 and 24 as straight grooves in this way, compared with the configuration in which the serpentine groove 20 is provided, the widths of the block land portions of the shoulder land portions 31 and 35 in the tire width direction B do not vary in the tire circumferential direction C. Therefore, it is possible to suppress the variation in the compression rigidity of each block land portion of the shoulder land portions 31 and 35 at positions in the tire circumferential direction C. Therefore, vibrations and noises caused by the variation in the compression rigidity of each block land portion of the shoulder land portions 31 and 35 at positions in the tire circumferential direction C can be suppressed.

[0066] Further, from another perspective, as shown in FIG. 2, in the present embodiment, the inner circumferential grooves 22 and 23 adjacent to the outer circumferential grooves 21 and 24 are constituted by the serpentine groove 20. And resonators 70 are disposed in land portions (intermediate land portions 32 and 34 in the present embodiment) partitioned from each other by the outer circumferential grooves 21 and 24 and the inner circumferential grooves 22 and 23 which are adjacent to the outer circumferential grooves 21 and 24 and constituted by the serpentine groove 20.

[0067] The resonator 70 is a Helmholtz resonator including an air chamber 71 and one or more outer constricted necks 72. The air chamber 71 is open to the tread surface of the land portion. The outer constricted neck 72 communicates the air chamber 71 with the outer circumferential grooves 21 and 24. More specifically, the outer constricted neck 72 of the resonator 70 provided in the intermediate land portion 32 communicates the air chamber 71 with the outer circumferential groove 21. Further, the outer constricted neck 72 of the resonator 70 provided in the intermediate land portion 34 communicates the air chamber 71 with the outer circumferential groove 24.

[0068] Further, the resonator 70 does not include an inner constricted neck that communicates the air chamber 71 with the inner circumferential grooves 22 and 23. That is, the resonator 70 provided in the intermediate land portion 32 does not include an inner constricted neck that communicates the air chamber 71 with the inner circumferential groove 22. Also, the resonator 70 provided in the intermediate land portion 34 does not include an inner constricted neck that communicates the air chamber 71 with the inner circumferential groove 23.

[0069] In this way, the Helmholtz resonator as the resonator 70 is provided in the land portion (intermediate land portions 32 and 34 in this embodiment) partitioned between the outer circumferential grooves 21 and 24 and the inner circumferential grooves 22 and 23 formed by the meandering grooves 20 adjacent to the outer circumferential grooves 21 and 24. The resonator 70 includes an outer constricted neck 72 that communicates the air chamber 71 with the outer circumferential grooves 21 and 24, and does not include an inner constricted neck that communicates the air chamber 71 with the inner circumferential grooves 22 and 23. With such a configuration, the resonator 70 can reduce the sound pressure peak of the air column resonance sound in the outer circumferential grooves 21 and 24. Further, since the resonator 70 does not include an inner constricted neck, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 that meanders in a sine wave shape are not divided by the inner constricted neck. When other conditions are the same, the rigidity of the land portion having the meandering groove wall as the side wall is smaller than the rigidity of the land portion having the groove wall extending straight along the tire circumferential direction C. Therefore, when the meandering first groove wall 20a and the second groove wall 20b are divided in the tire circumferential direction C, the rigidity of the land portion having the first groove wall 20a as the side wall and the land portion having the second groove wall 20b as the side wall may extremely decrease. Therefore, with the configuration in which the first groove wall 20a and the second groove wall 20b of the meandering groove 20 are not divided by the inner constricted neck as in this embodiment, it is possible to suppress an extreme decrease in the rigidity of the land portion provided with the resonator 70. As a result, a decrease in the braking performance of the tire 1 can be suppressed.

[0070] In each of the intermediate land portions 32 and 34, a plurality of resonators 70 are provided, which are arranged at intervals in the tire circumferential direction C. The distance between two adjacent resonators 70 among the plurality of resonators 70 provided in each of the intermediate land portions 32 and 34 in the tire circumferential direction C is set to be equal to or less than the contact length, which is the length of the tread contact surface in the tire circumferential direction C. Further, the length of the air chamber 71 of the resonator 70 in the tire circumferential direction C is also set to be equal to or less than the contact length. The air chamber 71 of the resonator 70 of the present embodiment has an elongated shape along the tire circumferential direction C in a tread surface view (see FIG. 2), but the shape is not particularly limited. In addition, each resonator 70 of the present embodiment includes only one outer constricted neck 72, but the number of outer constricted necks 72 is not particularly limited.

[0071] Furthermore, from still another viewpoint, as shown in FIG. 2, the four circumferential grooves 21 to 24 of the present embodiment include two inner circumferential grooves 22 and 23 that partition the central land portion 33 intersecting the tire equatorial plane CL. And, in the central land portion 33, a resonator including an air chamber opened to the tread surface and a constricted neck that communicates the air chamber with at least one of the two inner circumferential grooves 22 and 23 is not provided. That is, in the central land portion 33 intersecting the tire equatorial plane CL, a Helmholtz resonator such as the resonator 70 provided in the intermediate land portions 32 and 34 is not provided. By adopting such a configuration, it is possible to suppress a decrease in the rigidity of the central land portion 33 located at the center in the tire width direction B of the tread surface T.

[0072] In particular, in the present embodiment, the central land portion 33 is partitioned by two inner circumferential grooves 22 and 23 formed from the meandering groove 20. Therefore, if a Helmholtz resonator is provided in the central land portion 33, the constricted neck will be communicated with one of the two inner circumferential grooves 22 and 23. In such a case, as described above, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 are separated, so that the rigidity of the central land portion 33 may extremely decrease. Therefore, when the central land portion 33 is partitioned by two inner circumferential grooves 22 and 23 formed from the meandering groove 20 as in the present embodiment, it is preferable not to provide a Helmholtz resonator in the central land portion 33.

[0073] Note that the resonator 70, which is a Helmholtz resonator, can be modeled as having the shape shown in FIG. 6, and its resonance frequency f0 can be expressed by the following formula (2) when the outer constricted neck 72 has an extended length of l0, a cross-sectional area of S, the volume of the air chamber 71 is V, and the speed of sound is c.

[0074] TIFF0007716263000001.tif20163

[0075] However, the length l0 of the outer constricted neck 72 is preferably a value corrected at the open end in consideration that, in addition to the air inside the resonator 70, the air around the opening also vibrates additionally, rather than the measured value.

[0076] Therefore, the resonance frequency f0 of the resonator 70 can be changed as required by selecting the cross-sectional area S of the outer constricted neck 72, the length l0 of the outer constricted neck 72, the volume V of the air chamber 71, etc. Further, when there are a plurality of outer constricted necks 72 connected to one air chamber 71, it is known that there is no practical problem by performing the calculation considering that it is equivalent to one outer constricted neck 72 having a cross-sectional area obtained by summing the cross-sectional areas of these plurality of outer constricted necks 72 and having an extended length equal to the average length of the plurality of outer constricted necks 72.

[0077] Also, as described above, widthwise grooves 40 are formed in the shoulder lands 31, 35 partitioned from each other by the outer circumferential grooves 21, 24 and the tread ends TE of the tread surface T. Further, as described above, the widthwise grooves 40 of the present embodiment open to the outer circumferential grooves 21, 24, that is, are continuous with the outer circumferential grooves 21, 24.

[0078] Here, the width-direction groove 40 of the present embodiment is formed at a position overlapping with the extension line of the outer constricted neck 72 of the resonator 70. That is, when assuming an extension line obtained by extending the outer constricted neck 72 of the resonator 70 to the side opposite to the side connected to the air chamber 71, the width-direction grooves 40 of the shoulder lands 31 and 35 extend so as to overlap with this extension line. By adopting such a configuration, it is possible to achieve both drainage performance and appearance design.

[0079] Also, as shown in FIG. 2, the four circumferential-direction grooves 21 to 24 of the present embodiment include two inner circumferential-direction grooves 22 and 23 formed by the meandering groove 20. And the repetition period λ in the tire circumferential direction C of one inner circumferential-direction groove 22 formed by the meandering groove 20 has a phase difference in the tire circumferential direction C from the repetition period λ in the tire circumferential direction C of the other inner circumferential-direction groove 23 formed by the meandering groove 20. That is, the repetition period λ of the inner circumferential-direction groove 22 and the repetition period λ of the inner circumferential-direction groove 23 are shifted in the tire circumferential direction C. That is, the position of the maximum width Wmax of the inner circumferential-direction groove 22 and the position of the maximum width Wmax of the inner circumferential-direction groove 23 are different in the tire circumferential direction C. Similarly, the position of the minimum width Wmin of the inner circumferential-direction groove 22 and the position of the minimum width Wmin of the inner circumferential-direction groove 23 are different in the tire circumferential direction C. By doing so, excessive variation in the compression rigidity in the tire circumferential direction C can be suppressed. Thereby, noise can be suppressed.

[0080] The tire according to the present disclosure is not limited to the specific configuration shown in the above-described embodiments, and various modifications, changes, and combinations are possible without departing from the description of the claims. The tire 1 shown in the above-described embodiments includes four circumferential grooves 21 to 24 on the tread surface T, but any configuration may be adopted as long as it includes a circumferential groove formed by one or more meandering grooves 20. Therefore, the tire 1 may have a configuration including five or more circumferential grooves. In such a case, the five or more circumferential grooves are composed of two outer circumferential grooves and three or more inner circumferential grooves. Only one of these three or more inner circumferential grooves may be formed by the meandering groove 20. Also, a plurality of, but not all, of the three or more inner circumferential grooves may be formed by the meandering groove 20. Further, all of the three or more inner circumferential grooves may be formed by the meandering groove 20. When a plurality of inner circumferential grooves are formed by the meandering groove 20, as described above, from the viewpoint of suppressing variations in the compression rigidity in the tire circumferential direction C, it is preferable that the repetition period λ of the plurality of meandering grooves 20 has a phase difference in the tire circumferential direction C.

[0081] Also, the two inner circumferential grooves 22 and 23 in the above-described embodiments only have a phase difference in the tire circumferential direction C and are formed by meandering grooves 20 having the same shape and the same dimensions, but the two inner circumferential grooves 22 and 23 may be meandering grooves 20 having at least one of different shapes and dimensions. However, it is preferable that they are formed by meandering grooves 20 having the same shape and the same dimensions like the two inner circumferential grooves 22 and 23 in the above-described embodiments. By doing so, by providing a phase difference in the tire circumferential direction C between the two inner circumferential grooves 22 and 23, variations in the compression rigidity in the tire circumferential direction C can be easily suppressed.

[0082] Furthermore, the two inner circumferential grooves 22 and 23 formed by the meandering groove 20 of the above-described embodiment are formed at positions equidistant from the tire equatorial plane CL on both sides in the tire width direction B sandwiching the tire equatorial plane CL. Specifically, for example, the distance from the tire equatorial plane CL in the tire width direction B between the position of the groove width center at the position where the maximum width Wmax of the inner circumferential groove 22 is obtained and the position of the groove width center at the position where the maximum width Wmax of the inner circumferential groove 23 is obtained may be made equal. Note that it may also be the position of the groove width center at the position where the minimum width Wmin of the inner circumferential grooves 22 and 23 is obtained. Thus, when there are a plurality of meandering grooves 20, it is preferable that these plurality of meandering grooves 20 are arranged at positions equidistant from the tire equatorial plane CL on both sides in the tire width direction B sandwiching the tire equatorial plane CL. By doing so, it is possible to suppress variations in the influence of the axial force fluctuation caused by the meandering groove 20 between one side and the other side in the tire width direction B.

Industrial Applicability

[0083] The present disclosure relates to a tire.

Explanation of Signs

[0084] 1: Tire, 7: Tread rubber, 8: Side rubber, 11: Bead part, 11a: Bead core, 11b: Bead filler, 12: Sidewall part, 13: Tread part, 14: Carcass, 15: Belt, 16: Inner liner, 20: Sinuous groove, 20a: First groove wall, 20b: Second groove wall, 20c: Groove bottom, 21, 24: Outer circumferential direction groove (circumferential direction groove), 22, 23: Inner circumferential direction groove (circumferential direction groove, sinuous groove in the above embodiment), 31, 35: Shoulder land part, 32, 34: Intermediate land part, 33: Central land part, 40: Width direction groove, 51a: Wide part, 51b: Narrow part, 70: Resonator, 71: Air chamber, 72: Outer narrow neck, 120, 220: Sinuous groove as a comparative example, 120a, 220a: First groove wall of the sinuous groove of the comparative example, 120b, 220b: Second groove wall of the sinuous groove of the comparative example, A: Tire radial direction, B: Tire width direction, C: Tire circumferential direction, AP1: Amplitude of the first sine wave curve formed by the first groove wall, AP2: Amplitude of the second sine wave curve formed by the second groove wall, CL: Tire equatorial plane, D: Groove depth, L1 to L6: Sound waves, W: Groove width, λ: Repetition period

Claims

1. The tread surface is formed with meandering grooves extending along the tire circumferential direction, the groove width of the meandering groove in the tire width direction varies at a predetermined repetition period along the tire circumferential direction, when the maximum width of the groove width is Wmax and the minimum width of the groove width is Wmin, the ratio Wmin / Wmax which is the ratio of the maximum width and the minimum width is 0.35 to 0.85, both the first groove wall and the second groove wall which are both groove walls of the meandering groove extend while meandering in a sine wave shape with the predetermined repetition period as one cycle length in a tread surface view, in the tread surface view, a first sine wave curve formed by the first groove wall and a second sine wave curve formed by the second groove wall are arranged with a phase difference of 1 / 8 to 3 / 8 cycle in the tire circumferential direction, the tread surface is formed with three or more circumferential grooves extending along the tire circumferential direction, among the three or more circumferential grooves, one or more inner circumferential grooves located inside in the tire width direction than the outer circumferential grooves respectively located on both outer sides in the tire width direction are constituted by the meandering grooves, the one or more inner circumferential grooves include two inner circumferential grooves partitioning land portions from each other, the amplitudes of both groove walls of one of the two inner circumferential grooves and the amplitudes of both groove walls of the other of the two inner circumferential grooves are equal, tire.

2. The repetition period of the first sine wave curve and the second sine wave curve is 15 to 100 times the maximum amplitude in the tire width direction of the first sine wave curve and the second sine wave curve in a tread surface view, the tire according to Claim 1.

3. The outer circumferential groove extends linearly along the tire circumferential direction in a tread surface view, the tire according to Claim 1 or 2.

4. The one or more inner circumferential grooves include an inner circumferential groove adjacent to the outer circumferential groove, a resonator is disposed in a land portion partitioned from each other by the outer circumferential groove and the inner circumferential groove adjacent to the outer circumferential groove, the resonator is an air chamber opened to a tread surface of the land portion, and one or more outer constricted necks communicating the air chamber and the outer circumferential groove, The tire according to any one of claims 1 to 3, wherein the resonator does not include an inner constricted neck that communicates the air chamber and the inner circumferential groove adjacent to the outer circumferential groove.

5. On the shoulder land portion partitioned from each other by the outer circumferential groove and the tread end of the tread surface, a widthwise groove opening to the outer circumferential groove is formed at a position overlapping with an extension line of the outer constricted neck provided on the land portion. The tire according to claim 4.

6. The land portion partitioned from each other by the two inner circumferential grooves is a central land portion intersecting the tire equatorial plane, The tire according to claim 4 or 5, wherein a resonator including an air chamber opened to the tread surface and a constricted neck communicating the air chamber and at least one of the two inner circumferential grooves is not disposed on the central land portion.

7. The repeating period in the tire circumferential direction of one of the two inner circumferential grooves has a phase difference in the tire circumferential direction from the repeating period in the tire circumferential direction of the other of the two inner circumferential grooves. The tire according to any one of claims 1 to 6.

8. A meandering groove extending along the tire circumferential direction is formed on the tread surface, The groove width of the meandering groove in the tire width direction changes with a predetermined repeating period along the tire circumferential direction, When the maximum width of the groove width is Wmax and the minimum width of the groove width is Wmin, Wmin / Wmax, which is the ratio of the maximum width and the minimum width, is 0.35 to 0.85, The first groove wall and the second groove wall, which are both groove walls of the meandering groove, extend while meandering in a sine wave shape with the predetermined repeating period as one cycle length in a tread surface view, In the tread surface view, a first sine wave curve formed by the first groove wall and a second sine wave curve formed by the second groove wall are arranged with a phase difference of 1 / 8 to 3 / 8 cycle in the tire circumferential direction, Three or more circumferential grooves extending along the tire circumferential direction are formed on the tread surface, Among the three or more circumferential grooves, one or more inner circumferential grooves located inside the tire width direction from the outer circumferential grooves located most outside on both sides in the tire width direction are constituted by the meandering groove, Among the one or more inner circumferential grooves, the inner circumferential groove adjacent to the outer circumferential groove is constituted by the meandering groove, On the land portions partitioned from each other by the outer circumferential groove and the inner circumferential groove formed by the meandering groove adjacent to the outer circumferential groove, a resonator is disposed. The resonator is provided with an air chamber opened to the tread surface of the land portion, and one or more outer constriction necks communicating the air chamber with the outer circumferential groove. The resonator does not include an inner constriction neck that communicates the air chamber with the inner circumferential groove formed by the meandering groove adjacent to the outer circumferential groove. The tire. **Claim 9**: The repetition periods of the first sinusoidal curve and the second sinusoidal curve are 15 to 100 times the maximum amplitudes in the tire width direction of the first sinusoidal curve and the second sinusoidal curve in a tread surface view. The tire according to claim 8. **Claim 10**: The outer circumferential groove extends linearly along the tire circumferential direction in a tread surface view. The tire according to claim 8 or 9. **Claim 11**: In the shoulder land portion partitioned from each other by the outer circumferential groove and the tread end of the tread surface, a width direction groove opening to the outer circumferential groove is formed at a position overlapping the extension line of the outer constriction neck provided in the land portion. The tire according to any one of claims 8 to 10. **Claim 12**: The one or more inner circumferential grooves include two inner circumferential grooves that partition a central land portion intersecting the tire equatorial plane from each other. In the central land portion, a resonator including an air chamber opened to the tread surface and a constriction neck communicating the air chamber with at least one of the two inner circumferential grooves is not disposed. The tire according to any one of claims 8 to 11. **Claim 13**: The one or more inner circumferential grooves include two or more inner circumferential grooves formed by the meandering groove. The repetition period in the tire circumferential direction of one inner circumferential groove formed by the meandering groove has a phase difference in the tire circumferential direction from the repetition period in the tire circumferential direction of another inner circumferential groove formed by the meandering groove. The tire according to any one of claims 8 to 12.

Images