Tire

Abstract

To provide a tire which can secure steering stability when a vehicle is turned while maintaining drainage performance when wear of a tire progress.SOLUTION: A tire is a tire having three or more circumferential main grooves 2 on a tread 1, wherein at least one of a pair of shoulder main grooves 21a and 21b arranged at the outermost side in the tire width direction out of the three or more circumferential main grooves 2 is configured so that an inclination angle formed by groove walls 211a and 211b on a tread end TE side and the tread 1 is larger than 90°, and the at least one circumferential main groove 22 other than the pair of shoulder main grooves 21a and 21b is configured so that the maximum groove width position in a groove depth direction is a position closer to a groove bottom side than the tread position.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Conventionally, in order to suppress a decrease in drainage performance during tire wear progress, a tire having a groove whose bottom width widens has been disclosed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, there is a risk that the handling stability during vehicle turning may decrease.

[0005] Therefore, an object of the present invention is to provide a tire capable of ensuring the handling stability during vehicle turning while maintaining the drainage performance during tire wear progress.

Means for Solving the Problems

[0006] The gist of the present invention is as follows. A tire having three or more circumferential main grooves extending in the tire circumferential direction and having a groove width such that both side walls do not contact each other when the tire is in contact with the ground on the tread surface, Among the three or more circumferential main grooves, at least one of a pair of shoulder main grooves arranged on the outermost side in the tire width direction has an inclined angle formed by the groove wall on the tread end side and the tread surface being larger than 90°. Among the three or more circumferential main grooves, at least one circumferential main groove other than the pair of shoulder main grooves is configured such that the position of the maximum groove width in the groove depth direction is on the groove bottom side with respect to the tread surface position. A tire characterized by this. According to the tire of the present invention, it is possible to ensure the handling stability during vehicle turning while maintaining the drainage performance during tire wear progress.

[0007] In the tire of the present invention, It is preferable that the pair of shoulder main grooves are configured such that the inclination angle formed by the groove wall on the equatorial plane side of the tire and the tread surface is 90° or less. Thereby, it is possible to suppress a decrease in drainage performance at the time of new tires and during tire wear progress.

[0008] In the tire of the present invention, It is preferable to have a width direction groove that communicates with the shoulder main groove, extends in the tire width direction, and opens at the tread edge. Thereby, it is possible to effectively reduce the column resonance sound generated in the shoulder main groove and ensure sufficient drainage performance of the tire.

[0009] In the tire of the present invention, It is preferable that the groove width in the tread surface of the width direction groove is larger on the tread edge side than on the side communicating with the shoulder main groove. Thereby, it is possible to further reduce the column resonance sound generated in the shoulder main groove and ensure sufficient drainage performance.

Effect of the Invention

[0010] According to the present invention, it is possible to provide a tire capable of ensuring the handling stability during vehicle turning while maintaining the drainage performance during tire wear progress.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] The tire according to the present invention can be used for any type of tire, but is preferably applicable to passenger car tires. Hereinafter, embodiments of the tire according to the present invention will be exemplarily described with reference to the drawings. The same reference numerals are given to the common components in each figure.

[0013] The tires of each embodiment described in this specification may have any internal structure. The tires of each embodiment described in this specification may include, for example, a pair of bead cores (not shown) provided in a pair of bead portions, a pair of bead fillers (not shown) located on the outer side in the tire radial direction of the bead cores, a carcass 70 (FIG. 2), a belt 60 (FIG. 2), and a tread rubber 80 (FIG. 2). The carcass 70 extends in a toroidal shape between the pair of bead cores. The carcass 70 includes at least one layer (one layer in the example of the figure) of carcass ply. The carcass ply of the carcass 70 can have a configuration in which, for example, cords made of steel or organic fibers are coated with rubber. The carcass 70 can include, for example, a main body portion that extends in a toroidal shape between the pair of bead cores, and a pair of folded-back portions that are folded back from the innermost end in the tire radial direction of the main body portion toward the outer side in the tire width direction around the bead core on each of both sides with respect to the tire equatorial plane CL. The belt 60 is disposed on the outer side in the tire radial direction of the crown region of the carcass 70 in the tread portion 90 (FIG. 2). The belt 60 is composed of at least one layer (two layers in the example of the figure) of belt layers. The belt layer can have a configuration in which, for example, cords made of steel or organic fibers are coated with rubber. The tread rubber 80 is disposed on the outer side in the tire radial direction of the belt 60.

[0014] In this specification, the "tread surface (1)" means the outer peripheral surface that extends over the entire circumference of the tire and comes into contact with the road surface when a tire assembled to a rim and filled with a predetermined internal pressure is rolled while loaded with the maximum load. In this specification, the "tread edge (TE)" means the edge in the tire width direction of the tread surface (1). Also, in this specification, the "contact length" means the length along the tire circumferential direction on the contact surface between the tire and the road surface, and the "contact surface" means the outer peripheral surface of the tire that comes into contact with the road surface when a tire assembled to a rim and filled with a predetermined internal pressure is grounded while loaded with the maximum load. Here, the "rim" refers to the industrial standard effective in the region where the tire is produced and used. In Japan, it is the JATMA YEAR BOOK of JATMA (Japan Automobile Tire Manufacturers Association); in Europe, it is the STANDARDS MANUAL of ETRTO (The European Tyre and Rim Technical Organisation); in the United States, it is the YEAR BOOK of TRA (The Tire and Rim Association, Inc.), etc. It refers to the standard rim (Measuring Rim in the STANDARDS MANUAL of ETRTO, Design Rim in the YEAR BOOK of TRA) for the applicable size described or to be described in the future (that is, the above "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" can include the sizes described as "FUTURE DEVELOPMENTS" in the 2013 edition of the STANDARDS MANUAL of ETRTO). In the case of a size not described in the above industrial standards, it refers to a rim with a width corresponding to the bead width of the tire). Also, the "predetermined internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel for the applicable size and ply rating described in the above JATMA YEAR BOOK, etc. 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 defined for each vehicle on which the tire is mounted. The "maximum load" refers to the load corresponding to the above maximum load capacity. Note that the air referred to here can also be replaced with an inert gas such as nitrogen gas or others.

[0015] In this specification, unless otherwise specified, the dimensions of each element such as grooves and treads are measured in the "reference state" described below. In this specification, the "reference state" refers to the state in which the tire is assembled on the rim, filled with the above predetermined internal pressure, and unloaded.

[0016] In addition, in this specification, the "groove width of the circumferential main groove" refers to the length in the direction orthogonal to the extending direction of the circumferential main groove, measured in the above reference state. Similarly, the "groove width of the width-direction groove" refers to the length in the direction orthogonal to the extending direction of the width-direction groove, measured in the reference state.

[0017] [First Embodiment] Hereinafter, with reference to FIGS. 1, 2, and 3, the tire according to the first embodiment of the present invention will be described. FIG. 1 is a partial development view schematically showing the tread surface 1 of the tire 10 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the tire width direction showing a part of the tire 10 in FIG. 1 along the line A-A in FIG. 1. FIG. 3 is a partial cross-sectional view of the tire width direction schematically showing the circumferential main groove of the tire shown in FIG. 2.

[0018] As shown in FIG. 1, the tire 10 of the first embodiment has three or more circumferential main grooves 2 on the tread surface 1. Each circumferential main groove 2 extends in the tire circumferential direction. As shown in FIG. 1, each circumferential main groove 2 may extend linearly along the circumferential direction, or may extend in the circumferential direction in a zigzag shape or a wave shape or the like.

[0019] Each circumferential main groove 2 has a groove width such that both side walls do not contact each other when the tire is in contact with the ground. That is, when the tire is assembled to the rim, filled with a predetermined internal pressure, and loaded with the maximum load, a pair of groove walls facing each other at the position directly under the load are configured not to contact each other.

[0020] Of these three or more circumferential main grooves 2, a pair of circumferential main grooves arranged on the outermost side in the tire width direction are referred to as shoulder main grooves 21a and 21b. Also, among the three or more circumferential main grooves 2, circumferential main grooves other than the pair of shoulder main grooves 21a and 21b are referred to as center main grooves 22. In this embodiment, the center main groove 22 is one, but a plurality of them may be provided.

[0021] In addition, on the tread surface 1 of the tire 10 of the first embodiment, four land portions 31a, 31b, 32a, and 32b are defined by the shoulder main grooves 21a and 21b, the center main groove 22, and the tread edge TE. The shoulder land portions 31a and 31b are defined on the outer side in the tire width direction by the tread edge TE and the shoulder main grooves 21a and 21b, and the center land portions 32a and 32b are defined on the inner side in the tire width direction than the shoulder land portions 31a and 31b by the center main groove 22 and the shoulder main grooves 21a and 21b.

[0022] In the tire 10 of the first embodiment, at least one of the pair of shoulder main grooves arranged on the outermost side in the tire width direction, as shown in FIG. 3, the shoulder main grooves 21a and 21b, which are a pair of circumferential main grooves arranged on the outermost side in the tire width direction, are configured such that the inclination angles θ1 and θ2 formed by the groove walls 211a and 211b on the tread edge TE side and the tread surface 1 are each larger than 90°. The inclination angles θ1 and θ2 may change from the tread surface 1 to the groove bottom, but are configured to be larger than 90° from the tread surface 1 to the groove bottom. Also, the inclination angles θ1 and θ2 may be the same value or different values. When an asymmetric pattern is adopted, it is preferable that the inclination angle of the groove wall on the tread edge TE side of the shoulder main groove on the outer side where the vehicle is mounted exceeds 90°, and the inclination angle of the groove wall of the shoulder main groove on the inner side where the vehicle is mounted is not particularly limited.

[0023] In the present embodiment, among three or more circumferential main grooves 2, at least one circumferential main groove (center main groove 22 in the present embodiment) other than the pair of shoulder main grooves 21a and 21b is an extended-width main groove configured such that the position of the maximum groove width in the groove depth direction is on the groove bottom side with respect to the tread surface position. In this example, in the reference state, the center main groove 22 has the maximum groove width w1 at the groove bottom, and has a groove width smaller than the groove width w1 at any position on the outer side in the tire diameter direction, i.e., on the tread surface 1 side, from the groove bottom. In the present embodiment, the groove width gradually decreases from the groove width w1 side at the groove bottom toward the outer side in the tire diameter direction, and the groove width w2 on the tread surface 1 is the minimum groove width. Note that the center main groove 22 only needs to be configured such that the position of the maximum groove width in the groove depth direction is on the groove bottom side with respect to the tread surface position, and includes a configuration having a plurality of positions of the maximum groove width in the groove depth direction.

[0024] The operation and effect of the tire according to the first embodiment will be described. When the vehicle is turning, the contact length of the tire in the tire circumferential direction of the tire contact surface tends to be longer on the side farther in the tire width direction than on the side closer to the curve that the vehicle is trying to turn. Further, the input from the road surface and the load applied to the tire are also borne on the side with the longer contact length. Therefore, by making the inclination angle (in the present embodiment, the inclination angles θ1 and θ2 formed by the groove walls 211a and 211b on the tread end TE side of the pair of shoulder main grooves 21a and 21b and the tread surface 1, respectively) formed by the groove wall on the tread end TE side of the circumferential main groove arranged on the outermost side in the tire width direction and the tread surface greater than 90°, the opening end portion of the groove wall can be made less likely to be crushed, so that the rigidity of the land portion with respect to the tire width direction can be increased, and the handling stability during vehicle turning can be ensured.

[0025] Further, according to the tire of the present embodiment, since the maximum groove width position of the center main groove 22 is configured to be on the groove bottom side rather than the tread surface position, when the wear of the tire progresses, the portion with a large groove width is exposed on the tread surface 1, and compared with the case where the maximum groove width position of the center main groove 22 is at the tread surface position, the drainage performance during wear progression can be improved, and a decrease in drainage performance during wear progression can be suppressed. Since the center main groove 22 is located closer to the inner side in the tire width direction than the shoulder main grooves 21a and 21b, the contact pressure in the tire width direction when the tire is traveling straight tends to be relatively higher than that on the shoulder main groove side, and in particular, it is effective for ensuring sufficient drainage performance during straight running when wear progresses.

[0026] In addition, since the shoulder main grooves 21a and 21b and the center main groove 22 can have different shapes and the like in the cross-section in the tire width direction, the frequency of the air column resonance sound generated by the resonance of the air inside the tube surrounded by the circumferential main groove and the road surface when the vehicle is traveling is dispersed, the air column resonance sound can be effectively reduced, and the noise of the entire tire can be alleviated (it is difficult to feel annoying).

[0027] Hereinafter, the preferred configurations, modifications, and the like of the tire of the first embodiment will be described.

[0028] In the present embodiment, the inclination angles θ1 and θ2 formed by the groove walls 211a and 211b on the tread end TE side of the pair of shoulder main grooves 21a and 21b and the tread surface 1 are not particularly limited as long as they are inclination angles greater than 90°, but in order to increase the rigidity of the land portion with respect to the tire width direction and more effectively ensure the handling stability during vehicle turning, it is preferably 95° or more. From the viewpoint of effectively ensuring sufficient drainage performance, the inclination angles θ1 and θ2 are preferably 120° or less. More preferably, the inclination angles θ1 and θ2 are 100° or more and 130° or less.

[0029] In the present embodiment, it is preferable that the pair of shoulder main grooves 21a and 21b are configured such that the inclination angles θ3 and θ4 formed by the groove walls 212a and 212b on the tire equatorial plane CL side and the tread surface 1 are each 90° or less. Thereby, it is possible to suppress a decrease in drainage performance at the time of new tires and when tire wear progresses. The inclination angles θ3 and θ4 are preferably 70° or more in order to more effectively prevent uneven wear of the tire and ensure handling stability during vehicle turning. More preferably, the inclination angles θ3 and θ4 are 75° or more and 85° or less.

[0030] In addition, in the shoulder main groove 21a, the relationship between the opposing groove walls 211a and 212a is not particularly limited, and in the shoulder main groove 21b, the relationship between the opposing groove walls 211b and 212b is also not particularly limited. As shown in FIG. 3, for example, in a cross-sectional view in the tire width direction, the groove walls 211a and 212a and the groove walls 211b and 212b may be configured to be parallel to each other. According to such a configuration, the shoulder main grooves 21a and 21b have a shape with a constant groove width in the tire radial direction, so that compared with the main groove whose maximum groove width position is at the tread surface position, it is possible to effectively suppress a decrease in drainage performance when tire wear progresses. The present invention is not limited to the above configuration. For example, in a cross-sectional view in the tire width direction, the groove walls 211a and 212a and the groove walls 211b and 212b may be configured such that the groove width gradually increases from the tread surface 1 side toward the groove bottom side. According to such a configuration, the shoulder main grooves 21a and 21b can effectively suppress a decrease in drainage performance when tire wear progresses compared with the main groove whose maximum groove width position is at the tread surface position.

[0031] In the tire of the first embodiment, as long as each circumferential main groove 2 has a groove width such that both side walls do not contact each other when the tire is in contact with the ground, the groove width is not particularly limited. However, the minimum groove width of the center main groove 22 (groove width w2 in the example of FIG. 3) and the groove widths w3 and w4 of the shoulder main grooves 21a and 21b are preferably 1.5 mm or more. According to such a configuration, it is possible to contribute to maintaining the drainage performance both when the tire is new and when wear progresses. In this embodiment, the groove widths w3 and w4 of the shoulder main grooves 21a and 21b are constant from the tread surface 1 to the groove bottom in the tire radial direction. However, when the groove width is not constant, the minimum groove width is preferably 1.5 mm or more.

[0032] The groove depth (groove depths d1, d2, and d3 in FIG. 3) of each circumferential main groove 2 is preferably 3.0 mm or more. Thereby, it is possible to contribute to maintaining the drainage performance. From the viewpoint of the rigidity of the tire 10, the groove depth (groove depths d1, d2, and d3 in FIG. 3) of each circumferential main groove 2 is preferably 20 mm or less. More preferably, the groove depth of each circumferential main groove 2 is 3.0 mm or more from the viewpoint of maintaining the drainage performance and 15 mm or less from the viewpoint of the rigidity of the tire 10.

[0033] In the tire 10 of the first embodiment, the number of widened main grooves configured such that the maximum groove width position is at the groove bottom rather than the tread surface position is one (center main groove 22), but the number is not particularly limited. The number of widened main grooves is preferably one or more from the viewpoint of ensuring sufficient drainage performance particularly when wear progresses, and preferably three or less from the viewpoint of ensuring the handling stability of the tire 10.

[0034] Incidentally, circumferential main grooves that are not widened main grooves, for example, circumferential main grooves where the maximum groove width position is at the tread surface position, or circumferential main grooves configured such that opposing groove walls are parallel in a cross-sectional view in the tire width direction, are, in this embodiment, two of the pair of shoulder main grooves 21a and 21b arranged on the outermost side in the tire width direction. However, circumferential main grooves that are not widened main grooves can also be provided in three or more from the viewpoint of more effectively ensuring handling stability during vehicle turning. Circumferential main grooves that are not widened main grooves are preferably four or less from the viewpoint of suppressing a decrease in drainage performance when new and when tire wear progresses.

[0035] [Second Embodiment] Next, a tire according to another embodiment (second embodiment) of the present invention will be described with reference to FIG. 4. The tire 11 of the second embodiment has the same configuration as the tire 10 of the first embodiment except for having width direction grooves communicating with the pair of shoulder main grooves 21a and 21b. For the same configurations as in the first embodiment, the same reference numerals are given and their descriptions are omitted.

[0036] FIG. 4 is a partially developed view schematically showing the tread surface of the tire 11 according to the second embodiment of the present invention.

[0037] The tire 11 of the second embodiment has width direction grooves 4 that communicate with the shoulder main grooves 21a and 21b, respectively, extend in the tire width direction (at a predetermined angle exceeding 0° with respect to the tire width direction in this embodiment), and open to the tread edge TE.

[0038] In the tire 11 of the second embodiment, the width direction grooves 4 are arranged in the shoulder land portions 31a and 31b, communicate with the shoulder main grooves 21a or 21b, respectively, extend in the tire width direction, and open to the tread edge TE.

[0039] The width-direction groove 4 can be either line-symmetric or point-symmetric with respect to the tire equatorial plane CL, or it may not be either line-symmetric or point-symmetric with respect to the tire equatorial plane CL. In the example of Fig. 4, the width-direction groove 4 disposed in the shoulder land portion 31a and the width-direction groove 4 disposed in the shoulder land portion 31b are arranged in a state shifted in the tire circumferential direction from a point-symmetric state with respect to the tire equatorial plane CL.

[0040] By providing a width-direction groove 4 that communicates with the shoulder main grooves 21a and 21b, extends in the tire width direction, and opens to the tread edge TE, an air flow from the shoulder main grooves 21a and 21b toward the tread edge TE side and outward in the tire width direction is formed, and the column resonance sound generated in the shoulder main grooves 21a and 21b can be effectively reduced. Further, drainage from the shoulder main grooves 21a and 21b to the tread edge TE side can be promoted, and it is possible to contribute to maintaining the drainage performance of the tire more than in the case where no width-direction groove is provided.

[0041] Hereinafter, with reference to Figs. 4 and 5, a preferred configuration, a modification example, etc. of the width-direction groove 4 will be described. Fig. 5 is a partial development view schematically showing an enlarged part of the tread surface of Fig. 4. However, for convenience of explanation, Fig. 5 is drawn with a slightly different scale from Fig. 4.

[0042] Regarding the width-direction groove 4, although it is disposed in the shoulder land portions 31a and 31b respectively, as described above, in the example of Fig. 4, except that it is arranged in a state shifted in the tire circumferential direction from a point-symmetric state with respect to the tire equatorial plane CL, since it has the same configuration, the width-direction groove 4 disposed in the shoulder land portion 31a will be described as a typical example below.

[0043] The width-direction groove 4 may have a constant groove width shape on the tread surface 1, or may have a shape in which the groove width changes in the middle of the tire width direction. It is preferable that the groove width of the width-direction groove 4 on the tread surface 1 is larger on the side opening to the tread edge TE side than on the side communicating with the shoulder main groove 21a. As shown in FIG. 5, the width-direction groove 4 includes a first width-direction groove portion 4a communicating with the shoulder main groove 21a, and a second width-direction groove portion 4b that is adjacent to and continuous with the tread edge TE side of the first width-direction groove portion 4a and opens to the tread edge TE. The groove width w6 of the second width-direction groove portion 4b on the tread surface 1 is larger than the groove width w5 of the first width-direction groove portion 4a on the tread surface 1. According to such a configuration, by forming an air flow from the narrow first width-direction groove portion 4a communicating with the shoulder main groove 21a to the wide second width-direction groove portion 4b, the air flow to the outer side in the tire width direction can be promoted, and the column resonance sound can be further reduced. In addition, moisture easily flows from the narrow first width-direction groove portion 4a to the wide second width-direction groove portion 4b, and drainage to the tread edge TE side can be promoted, which easily contributes to maintaining the drainage performance of the tire.

[0044] Further, in the width-direction groove 4, it is preferable that the groove width w5 of the first width-direction groove portion 4a communicating with the shoulder main groove 21a has a groove width that is 1 mm or more narrower than the groove width w6 of the second width-direction groove portion 4b. According to such a configuration, the reduction effect of the column resonance sound can be further enhanced.

[0045] In the tire 11 of the second embodiment, it is preferable that the groove width w5 of the first width-direction groove portion 4a on the tread surface 1 is 0.3 mm or more. According to such a configuration, sufficient air can flow from the shoulder main groove 21a into the first width-direction groove portion 4a, and the function of reducing the column resonance sound can be more effectively exerted. More preferably, it is 0.4 mm or more.

[0046] In the width direction groove 4, the groove width w6 on the tread surface 1 of the second width direction groove portion 4b opening to the tread edge TE may have a groove width such that both side walls do not contact each other when the tire is in contact with the ground, but it is more preferable to have a groove width of 1.5 mm or more. With such a configuration, the effect of reducing the air column resonance sound can be effectively realized, and it can contribute to maintaining drainage performance.

[0047] The groove depth of the first width direction groove portion 4a of the width direction groove 4 is preferably set to be approximately the same as the groove depth of the second width direction groove portion 4b. This is because with such a configuration, even in a worn tire, drainage performance can be maintained and the air column resonance sound can be reduced.

[0048] Also, in the width direction groove 4, the groove depth of the second width direction groove portion 4b is preferably set to be approximately the same depth as the shoulder main groove 21a. More specifically, the groove depth of the second width direction groove portion 4b is preferably 3.0 mm or more. Thereby, it can contribute to maintaining drainage performance. From the viewpoint of the rigidity of the tire 11, the groove depth of the second width direction groove portion 4b is preferably 20 mm or less. More preferably, from the viewpoint of maintaining drainage performance, the groove depth of the second width direction groove portion 4b is 3.0 mm or more, and from the viewpoint of the rigidity of the tire 10, it is 15 mm or less.

[0049] In the example of FIGS. 4 and 5, the length L1 along the extending direction of the first width direction groove portion 4a of the width direction groove 4 is shorter than the length L2 along the extending direction of the second width direction groove portion 4b. However, it is not limited to such a configuration. As shown in FIG. 6, the length L1 along the extending direction of the first width direction groove portion 4a may be longer than the length L2 along the extending direction of the second width direction groove portion 4b. However, it is more preferable that the length L1 is shorter than the length L2 from the viewpoint of providing a volume difference between the first width direction groove portion 4a and the second width direction groove portion 4b and reducing the air column resonance sound.

[0050] In the tread surface 1, the widthwise groove 4 preferably has an inclination angle θ5 (Fig. 4) with respect to the tire width direction of 0° to 20°. By setting the inclination angle to 0° or more and 20° or less, while preventing uneven wear at the opening end of the widthwise groove 4 with respect to the shoulder main groove 21a, it is possible to reduce the column resonance sound and suppress the generation of other noises. The inclination angle θ5 is more preferably 5° to 15° from the viewpoints of preventing uneven wear and suppressing the generation of other noises.

[0051] In the second embodiment, the widthwise grooves 4 are preferably arranged at both ends of the ground contact surface of the tire 11 so that the total number in the ground contact surface is 4 to 10 at both ends of the ground contact surface. Here, the "number in the ground contact surface" means that if even a part of the widthwise groove 4 is located within the ground contact surface, it is considered to be located within the ground contact surface. According to such a configuration, it is possible to more effectively reduce the column resonance sound and contribute to maintaining drainage performance.

[0052] More specifically, the widthwise grooves 4 are preferably arranged at intervals of 10 to 40 mm in the tire circumferential direction on one side of the tread end TE with the tire equatorial plane CL as a boundary. According to such a configuration, it is possible to more effectively reduce the column resonance sound and contribute to maintaining drainage performance. More preferably, they are arranged at intervals of 20 to 30 mm in the tire circumferential direction.

Industrial Applicability

[0053] The tire according to the present invention can be used for any type of pneumatic tire, but is preferably applicable to pneumatic tires for passenger cars.

Explanation of Reference Numerals

[0054] 1: Tread surface, 2: Circumferential main groove, 4: Width direction groove, 4a: First width direction groove part, 4b: Second width direction groove part, 10, 11: Tires, 21a, 21b: Shoulder main grooves, 22: Center main groove, 31a, 31b: Shoulder land parts, 32a, 32b: Center land parts, 60: Belt, 70: Carcass, 80: Tread rubber, 90: Tread part, 211a, 211b, 212a, 212b: Groove walls, CL: Tire equatorial plane, TE: Tread end

Claims

1. A tire having three or more circumferential main grooves extending in the tire circumferential direction and having a groove width such that both side walls do not contact each other when the tire is in contact with the ground, on a tread surface, wherein the tire is assembled to a rim, filled with a predetermined internal pressure, and in a reference state of no load, all of a pair of shoulder main grooves arranged on the outermost side in the tire width direction among the three or more circumferential main grooves are configured such that an inclination angle formed by a groove wall on the tread end side and the tread surface is greater than 90°, when the circumferential main grooves other than the pair of shoulder main grooves are referred to as center main grooves, all of the center main grooves are configured such that a position of a maximum groove width in the groove depth direction is a position of a groove bottom, and a position of a minimum groove width in the groove depth direction is a tread surface position, the center main grooves are trapezoidal in a cross section in the tire width direction, the pair of shoulder main grooves are configured such that an inclination angle formed by a groove wall on the equatorial plane side of the tire and the tread surface is 90° or less, a tire characterized by that.

2. The tire according to claim 1, further comprising a width direction groove that communicates with the shoulder main groove, extends in the tire width direction, and opens at a tread end.

3. The tire according to claim 2, wherein the width direction groove has a groove width on the tread surface that is larger on the tread end side than on the side communicating with the shoulder main groove.

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