JP7155847B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire, and more particularly to a tire with a specified mounting orientation on a vehicle.

Patent Literature 1 listed below proposes a tire whose mounting direction to a vehicle is specified. The tread portion of this tire is divided into three land portions by two circumferential main grooves. In addition, in order to improve steering stability, the tire is configured such that the widest land portion, which is the widest among the three land portions, is positioned on the outer side of the vehicle when mounted on the vehicle.

JP 2015-217907 A

The tire of Patent Document 1 has room for further improvement in terms of noise performance and wet performance.

The present invention has been devised in view of the actual situation as described above, and a main object of the present invention is to provide a tire capable of improving steering stability, noise performance and wet performance in a well-balanced manner.

The present invention relates to a tire having a specified mounting direction on a vehicle, and a tread portion having an outer tread end positioned on the outer side of the vehicle when mounted on the vehicle and an inner tread end positioned on the inner side of the vehicle when mounted on the vehicle. and the tread portion includes a first main groove extending continuously in the tire circumferential direction between the outer tread edge and the tire equator, and a tire circumferentially continuous main groove between the inner tread edge and the tire equator. an outer land portion partitioned between the outer tread edge and the first main groove; and an inner land partitioned between the second main groove and the inner tread edge. wherein the outer land portion is provided with a plurality of outer lateral grooves extending from the first main groove and discontinuous within the outer land portion, and the inner land portion is provided with a plurality of outer lateral grooves extending from the inner tread edge and A plurality of inner lateral grooves are provided that are interrupted within the inner land portion.

In the tire of the present invention, it is preferable that the axial width of the outer land portion and the axial width of the inner land portion are each 0.25 to 0.35 times the tread width.

In the tire of the present invention, it is preferable that the axial width of the outer land portion is the same as the axial width of the inner land portion.

In the tire of the present invention, the land ratio of the outer land portion is preferably larger than the land ratio of the inner land portion.

In the tire of the present invention, the land ratio of the outer land portion is preferably 1.03 to 1.08 times the land ratio of the inner land portion.

In the tire of the present invention, it is preferable that the groove width of the outer lateral grooves is smaller than the groove width of the inner lateral grooves.

In the tire of the present invention, the groove width of the outer lateral grooves is preferably 0.40 to 0.60 times the groove width of the inner lateral grooves.

In the tire of the present invention, the angle of the outer lateral grooves with respect to the tire axial direction is preferably larger than the angle of the inner lateral grooves with respect to the tire axial direction.

In the tire of the present invention, it is preferable that the angle of the inner lateral groove with respect to the tire axial direction is 0 to 10 degrees, and the angle of the outer lateral groove with respect to the tire axial direction is 15 to 25 degrees.

In the tire of the present invention, it is preferable that the outer lateral grooves are discontinued on the first main groove side of the center position of the outer land portion in the tire axial direction.

In the tire of the present invention, the axial length of the outer lateral groove is preferably 0.30 to 0.40 times the axial width of the outer land portion.

In the tire of the present invention, it is preferable that the inner lateral groove is discontinued on the second main groove side of the center position of the inner land portion in the tire axial direction.

In the tire of the present invention, the axial length of the inner lateral groove is preferably 0.60 to 0.70 times the axial width of the inner land portion.

In the tire of the present invention, it is preferable that the tread portion is composed of three land portions separated by the first main groove and the second main groove.

The tread portion of the tire of the present invention includes a first main groove that extends continuously in the tire circumferential direction between the outer tread edge and the tire equator, and a tire circumferentially continuous groove that extends between the inner tread edge and the tire equator. It has a second main groove extending therefrom, an outer land portion defined between the outer tread edge and the first main groove, and an inner land portion defined between the second main groove and the inner tread edge.

In the present invention, the outer land portion is provided with a plurality of outer lateral grooves extending from the first main groove and interrupted within the outer land portion. The outer lateral groove exhibits excellent drainage performance together with the first main groove. In addition, the outer lateral groove moderately relaxes the rigidity of the outer land portion in the vicinity of the first main groove, and thus helps reduce the hitting sound when the edge of the outer land portion on the first main groove side touches the ground. Moreover, the outer lateral grooves are discontinued within the outer land portion, thereby maintaining the rigidity of the outer land portion in the vicinity of the outer tread edge. Therefore, excessive deformation of the outer land portion during turning is suppressed, and steering stability is maintained.

In the present invention, the inner land portion is provided with a plurality of inner lateral grooves extending from the inner tread edge and interrupted within the inner land portion. Since high ground contact pressure tends to act on the inner land portion when the vehicle travels straight, the inner lateral grooves can exhibit high drainage performance when the vehicle travels straight. In addition, since the inner lateral groove moderately reduces the rigidity of the inner land portion near the inner tread edge, it is possible to reduce the impact sound when the inner tread edge touches the ground. Moreover, since the inner lateral groove is discontinued within the inner land portion, the rigidity of the inner land portion on the second main groove side is maintained high. This suppresses rapid deformation of the inner land portion when the center of the contact patch of the tire moves toward the outer land portion during turning. Therefore, steering response during turning becomes linear, and excellent steering stability is obtained.

As described above, the tire of the present invention can improve steering stability, noise performance and wet performance in a well-balanced manner.

1 is a developed view of a tread portion of a tire according to one embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the inner land portion of FIG. 1; FIG. 3 is a cross-sectional view taken along line AA of FIG. 2; FIG. 2 is an enlarged view of the outer land portion of FIG. 1; FIG. 5 is a cross-sectional view taken along line BB of FIG. 4; FIG. 2 is an enlarged view of an intermediate land portion of FIG. 1; FIG. 7 is a cross-sectional view taken along line CC of FIG. 6; FIG. 3 is a developed view of a tread portion of a tire of a comparative example;

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a developed view of a tread portion 2 of a tire 1 of this embodiment. The tire 1 of the present embodiment is configured as, for example, a pneumatic tire for passenger cars. The tire 1 of the present embodiment is preferably used as a tire for light vehicles.

As shown in FIG. 1, the tire 1 of the present embodiment is specified, for example, in the mounting direction to the vehicle. The mounting direction to the vehicle is displayed, for example, on the sidewall portion (not shown) of the tire 1 using characters, graphics, or the like. When the tire 1 is mounted on a vehicle, the right side of FIG. 1 corresponds to the inner side of the vehicle, and the left side of FIG. 1 corresponds to the outer side of the vehicle.

By specifying the mounting direction to the vehicle, the tread portion 2 is provided with an inner tread end Ti positioned on the vehicle inner side when mounted on the vehicle and an outer tread end To positioned on the vehicle outer side when mounted on the vehicle. there is

In the case of a pneumatic tire, the inner tread edge Ti and the outer tread edge To are the outermost ground contact positions in the tire axial direction when the tire 1 in a normal state is grounded on a flat surface with a camber angle of 0° with a normal load applied. A normal state is a state in which the tire is mounted on a normal rim, is inflated to a normal internal pressure, and has no load. In this specification, unless otherwise specified, the dimensions of each part of the tire are values measured under normal conditions.

A "regular rim" is a rim defined for each tire in a system of standards that includes the standards on which tires are based. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure determined for each tire by each standard in the standard system including the standard on which the tire is based. Maximum value described in VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Normal load" is the load defined for each tire by each standard in the standard system including the standard on which the tire is based. AT VARIOUS COLD INFLATION PRESSURES", and "LOAD CAPACITY" for ETRTO.

The tread portion 2 has a first main groove 3 and a second main groove 4 that extend continuously in the tire circumferential direction with the tire equator C interposed therebetween.

The first main groove 3 and the second main groove 4 extend continuously in the tire circumferential direction with a relatively large width and depth in order to discharge water on the road surface to the rear of the tire. In a preferred embodiment, each main groove has a groove width and depth of 5 mm or more, more preferably 6 mm or more. The groove width W1 of each main groove is, for example, 8.0% to 13.0%, preferably 9.0% to 11.0%, of the tread width TW. The tread width TW is the axial distance of the tire from the inner tread end Ti to the outer tread end To in the normal state. Each main groove, for example, extends straight along the tire circumferential direction. Alternatively, each main groove may be non-linear, such as zig-zag or wavy.

The first main groove 3 is arranged, for example, between the tire equator C and the outer tread edge To. The second main groove 4 is arranged, for example, between the tire equator C and the inner tread edge Ti. The axial distance L1 from the tire equator C to the groove centerline of the first main groove 3 or the second main groove 4 is preferably 0.10 to 0.20 times the tread width TW, for example. In a preferred embodiment, the difference between the axial distance from the tire equator C to the groove center line of the first main groove 3 and the tire axial distance from the tire equator C to the groove center line of the second main groove 4 is , less than 3% of the tread width TW.

The tread portion 2 is composed of, for example, three land portions divided into first main grooves 3 and second main grooves 4 . Specifically, the tread portion 2 is composed of an outer land portion 6 , an intermediate land portion 7 and an inner land portion 8 . The outer land portion 6 is divided between the outer tread edge To and the first main groove 3 . The intermediate land portion 7 is divided between the first main groove 3 and the second main groove 4 . The inner land portion 8 is divided between the inner tread edge Ti and the second main groove 4 . The tread portion 2 of this embodiment has an asymmetrical pattern about the tire equator C. As shown in FIG.

In the present invention, the outer land portion 6 is provided with a plurality of outer lateral grooves 23 . The outer lateral groove 23 extends from the first main groove 3 and is discontinued within the outer land portion 6 . The outer lateral grooves 23 exhibit excellent drainage properties together with the first main grooves 3 . In addition, since the outer lateral grooves 23 moderately reduce the rigidity of the outer land portion 6 near the first main grooves 3, the impact sound when the edge of the outer land portion 6 on the first main groove 3 side touches the ground is reduced. help to do. Moreover, the outer lateral grooves 23 are interrupted within the outer land portion 6, so that the rigidity of the outer land portion 6 near the outer tread end To can be maintained. Therefore, excessive deformation of the outer land portion 6 during turning is suppressed, and steering stability is maintained.

A plurality of inner lateral grooves 20 are provided in the inner land portion 8 . The inner lateral groove 20 extends from the inner tread edge Ti and discontinues within the inner land portion 8 . Since high ground contact pressure tends to act on the inner land portion 8 when the vehicle travels straight, the inner lateral grooves 20 can exhibit high drainage performance when the vehicle travels straight. In addition, since the inner lateral groove 20 moderately reduces the rigidity of the inner land portion 8 near the inner tread edge Ti, it is possible to reduce the impact sound when the inner tread edge Ti touches the ground. Moreover, since the inner lateral groove 20 is discontinued within the inner land portion 8, the rigidity of the inner land portion 8 on the side of the second main groove 4 is maintained high. As a result, sudden deformation of the inner land portion 8 is suppressed when the center of the contact patch of the tire moves toward the outer land portion 6 during turning. Therefore, steering response during turning becomes linear, and excellent steering stability is obtained.

A more detailed configuration of each unit will be described below. An enlarged view of the inner land portion 8 is shown in FIG. As shown in FIG. 2, the width W3 of the inner land portion 8 in the tire axial direction is, for example, 0.25 to 0.35 times the tread width TW (shown in FIG. 1 and the same applies hereinafter). It is desirable to have

The groove width W4 of the inner lateral groove 20 is preferably, for example, 0.25 to 0.35 times the groove width W1 (shown in FIG. 1) of the main groove.

The axial length L5 of the inner lateral groove 20 is, for example, 0.30 to 0.70 times the axial width W3 of the inner land portion 8, and more preferably 0.60 to 0.70 times. be. For example, it is more desirable that the inner lateral groove 20 discontinues on the second main groove 4 side of the center position of the inner land portion 8 in the tire axial direction.

The inner lateral groove 20 is arranged, for example, at an angle θ3 of 0 to 10° with respect to the axial direction of the tire. In a desirable aspect, the angle of the inner lateral groove 20 with respect to the tire axial direction gradually increases inward in the tire axial direction.

It is desirable that the length P2 of one pitch in the tire circumferential direction between two inner lateral grooves 20 adjacent in the tire circumferential direction is larger than the axial width W3 of the inner land portion 8, for example. Specifically, the one-pitch length P2 of the inner lateral grooves 20 is preferably 1.05 to 1.15 times the width W3 of the inner land portion 8 . Such an arrangement of the inner lateral grooves 20 can enhance steering stability and wet performance in a well-balanced manner.

The inner land portion 8 of the present embodiment is provided with, for example, a plurality of inner sipes 21 . In this specification, the term "sipe" means a cut with a width of less than 1.5 mm. In a preferred embodiment, the sipe width is 1.0 mm or less.

The inner sipe 21 extends from the inner tread edge Ti to the second main groove 4, for example. In this embodiment, for example, the inner sipes 21 and the inner lateral grooves 20 are alternately provided in the tire circumferential direction.

The inner sipe 21 is inclined in the same direction as the inner lateral groove 20 with respect to the tire axial direction, for example. The angle θ4 of the inner sipe 21 with respect to the axial direction of the tire is, for example, 5 to 15°. The angle of the inner sipe 21 of this embodiment with respect to the axial direction of the tire gradually increases inward in the axial direction of the tire. Also, the maximum angle of the inner sipe 21 with respect to the tire axial direction is larger than the maximum angle of the inner lateral groove 20 with respect to the tire axial direction. Such an inner sipe 21 can provide a frictional force in the axial direction of the tire during wet running.

It is desirable that one pitch length P3 in the tire circumferential direction between two inner sipes 21 adjacent in the tire circumferential direction is larger than, for example, the axial width W3 of the inner land portion 8 . Specifically, the one-pitch length P3 of the inner sipe 21 is preferably 1.05 to 1.15 times the width W3 of the inner land portion 8 . Further, in this embodiment, the inner lateral grooves 20 and the inner sipes 21 are arranged with the same length of one pitch.

FIG. 3 shows a cross-sectional view of the inner sipe 21 of FIG. 2 along line AA. As shown in FIG. 3, the inner sipe 21 includes, for example, a body portion 21a and a shallow portion 21b having a depth smaller than that of the body portion 21a. Such an inner sipe 21 can maintain the rigidity of the inner land portion 8 and further improve steering stability.

The shallow bottom portion 21b is desirably provided, for example, closer to the tire equator C than the discontinuous end of the inner lateral groove 20 (shown in FIG. 2). Moreover, it is desirable that the shallow bottom portion 21b does not overlap with an area obtained by virtually extending the inner lateral groove 20 parallel to the tire circumferential direction. The shallow bottom portion 21b of the present embodiment is provided, for example, at the end portion of the inner sipe 21 on the tire equator C side. Such a shallow bottom portion 21b maintains high rigidity of the inner land portion 8 on the side of the second main groove 4, and can further enhance steering stability.

In order to improve wet performance and steering stability in a well-balanced manner, it is desirable that the depth d2 of the shallow bottom portion 21b is, for example, 0.30 to 0.60 times the depth d1 of the main body portion 21a.

As shown in FIG. 2, the inner land portion 8 preferably does not have lateral grooves extending from the inner tread edge Ti to the second main grooves 4 . Such an inner land portion 8 has high rigidity and can exhibit excellent steering stability.

FIG. 4 shows an enlarged view of the outer land portion 6. As shown in FIG. As shown in FIG. 4, it is desirable that the axial width W5 of the outer land portion 6 is, for example, 0.25 to 0.35 times the tread width TW. In a more desirable aspect, the width W5 of the outer land portion 6 is the same as the axial width W3 of the inner land portion 8 .

The groove width W7 of the outer lateral grooves 23 is preferably smaller than the groove width W4 of the inner lateral grooves 20 (shown in FIG. 2), for example. Specifically, the groove width W7 of the outer lateral grooves 23 is preferably 0.40 to 0.60 times the groove width W4 of the inner lateral grooves 20. As shown in FIG. As a result, the pumping sounds of the inner lateral grooves 20 and the outer lateral grooves 23 are turned into white noise, and excellent noise performance is obtained. In addition, such outer lateral grooves 23 can improve steering stability and wet performance in a well-balanced manner.

The axial length L8 of the outer lateral groove 23 is, for example, 0.25 to 0.45 times the axial width W5 of the outer land portion 6, and more preferably 0.30 to 0.40 times. be. It is more desirable that the outer lateral groove 23 discontinues, for example, on the first main groove 3 side of the center position of the outer land portion 6 in the tire axial direction.

The angle θ7 of the outer lateral grooves 23 with respect to the tire axial direction is preferably larger than the angle θ3 of the inner lateral grooves 20 with respect to the tire axial direction. Specifically, the angle θ7 of the outer lateral groove 23 with respect to the axial direction of the tire is, for example, 15 to 25°.

It is desirable that the length P6 of one pitch in the tire circumferential direction of two adjacent outer lateral grooves 23 in the tire circumferential direction is larger than the axial width W5 of the outer land portion 6, for example. Specifically, the one-pitch length P6 of the outer lateral groove 23 is 1.05 to 1.15 times the width W5 of the outer land portion 6. As shown in FIG. Such arrangement of the outer lateral grooves 23 can improve steering stability and wet performance in a well-balanced manner.

The outer land portion 6 of the present embodiment is provided with, for example, a plurality of outer sipes 25 . The outer sipe 25 extends, for example, from the first main groove 3 to the outer tread edge To. In this embodiment, for example, the outer sipes 25 and the outer lateral grooves 23 are provided alternately in the tire circumferential direction.

The outer sipes 25 are inclined in the same direction as the outer lateral grooves 23 with respect to the axial direction of the tire, for example. An angle θ8 of the outer sipe 25 with respect to the axial direction of the tire is, for example, 10 to 25°. The angle of the outer sipe 25 of this embodiment with respect to the axial direction of the tire gradually increases inward in the axial direction of the tire. Further, the maximum angle of the outer sipe 25 with respect to the tire axial direction is larger than the maximum angle of the inner sipe 21 with respect to the tire axial direction. Such an outer sipe 25 can provide a frictional force in the axial direction of the tire during wet running.

It is desirable that the length P7 of one pitch in the tire circumferential direction between the two outer sipes 25 adjacent in the tire circumferential direction is larger than the axial width W5 of the outer land portion 6, for example. Specifically, the one-pitch length P7 of the outer sipe 25 is 1.05 to 1.15 times the width W5 of the outer land portion 6. As shown in FIG. Such arrangement of the outer sipes 25 can enhance steering stability and wet performance in a well-balanced manner.

FIG. 5 shows a cross-sectional view of the outer sipe 25 of FIG. 4 taken along line BB. As shown in FIG. 5, the outer sipe 25 includes, for example, a body portion 25a and a shallow portion 25b having a depth smaller than that of the body portion 25a. Such outer sipes 25 can maintain the rigidity of the outer land portion 6 and further enhance steering stability.

The shallow bottom portion 25b of the outer sipe 25 is provided, for example, closer to the tire equator C than the center position of the outer land portion 6 in the tire axial direction. The shallow bottom portion 25b of the present embodiment is provided, for example, at the end portion of the outer sipe 25 on the tire equator C side.

The axial length L10 of the shallow portion 25b of the outer sipe 25 is preferably longer than the axial length L9 (shown in FIG. 3) of the shallow portion 21b of the inner sipe 21, for example. Specifically, the length L10 of the shallow portion 25b of the outer sipe 25 is 1.30 to 2.00 times the length L9 of the shallow portion 21b of the inner sipe 21. As shown in FIG. Such an outer sipe 25 causes an appropriate rigidity difference between the outer land portion 6 and the inner land portion 8 . As a result, when the center of the contact patch of the tire moves toward the outer land portion during turning, the steering response becomes linear, and excellent steering stability is obtained. The length of each shallow portion is measured in a region excluding, for example, a portion where the depth changes on the main body side.

In order to improve wet performance and steering stability in a well-balanced manner, the depth d4 of the shallow bottom portion 25b of the outer sipe 25 is, for example, 0.30 to 0.60 times the depth d3 of the main body portion 25a of the outer sipe 25. It is desirable to have

As shown in FIG. 4, the outer land portion 6 preferably does not have lateral grooves extending from the outer tread edge To to the first main grooves 3 . Such an outer land portion 6 has high rigidity and can exhibit excellent steering stability.

The land ratio of the outer land portion 6 is desirably larger than the land ratio of the inner land portion 8 . Specifically, the land ratio of the outer land portion 6 is preferably 1.03 to 1.08 times the land ratio of the inner land portion 8 . Such an outer land portion 6 can further enhance steering stability. In this specification, the "land ratio" is the ratio Sb/Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact area in which all grooves and sipes are filled.

FIG. 6 shows an enlarged view of the intermediate land portion 7. As shown in FIG. As shown in FIG. 6, it is desirable that the axial width W2 of the intermediate land portion 7 is, for example, 0.15 to 0.25 times the tread width TW.

The intermediate land portion 7 is desirably located on the tire equator C, for example. In this embodiment, the central position of the intermediate land portion 7 in the tire axial direction is arranged near the tire equator C. As shown in FIG. More specifically, the axial distance between the tire equator C and the axial center position of the intermediate land portion 7 is less than 10% of the axial width W2 of the intermediate land portion 7 .

An intermediate sipe 10 that completely crosses the intermediate land portion 7 is provided in the intermediate land portion 7 . The intermediate sipe 10 has a central portion 12 , a first outer portion 13 and a second outer portion 14 . The central portion 12 is inclined in one direction with respect to the tire axial direction. The first outer portion 13 is inclined in the opposite direction to the central portion 12 on the first main groove 3 side. The second outer portion 14 is inclined in the opposite direction to the central portion 12 on the second main groove 4 side.

Such an intermediate sipe 10 can prevent all of its edges from contacting the ground at the same time, thereby reducing the impact sound when the edges contact the ground.

In addition, when the intermediate sipe 10 closes due to ground pressure acting on the intermediate land portion 7, the contacting sipe walls mesh with each other, thereby suppressing shear deformation of the intermediate land portion 7 with the intermediate sipe 10 as a boundary. do. Therefore, excellent steering stability is obtained.

The intermediate sipe 10 extends, for example, in a smooth curve and forms one wave cycle. However, the intermediate sipe 10 is not limited to such a mode, and the intermediate sipe 10 may be partially extended linearly, for example.

The central portion 12 of this embodiment crosses the tire equator C. As shown in FIG. The center portion 12 crosses the center position of the intermediate land portion 7 in the axial direction of the tire. The central portion 12 includes, for example, a linearly extending portion 12a that crosses the tire equator C. As shown in FIG. The central portion 12 includes a portion whose angle with respect to the tire axial direction gradually decreases toward the first outer portion 13 or the second outer portion 14 side.

The length L2 of the central portion 12 in the axial direction of the tire is preferably, for example, 0.50 times or more the width W2 of the intermediate land portion 7 in the axial direction of the tire. Specifically, the length L2 of the central portion 12 is 0.50 to 0.70 times the width W2 of the intermediate land portion 7, for example. Such a central portion 12 can exhibit the above effects while suppressing uneven wear of the intermediate land portion 7 .

It is desirable that the maximum angle θ1 of the central portion 12 with respect to the axial direction of the tire is, for example, less than 45°. Specifically, the angle θ1 of the central portion 12 is preferably 10 to 30°. Such a central portion 12 can improve noise performance and steering stability in a well-balanced manner.

The first outer portion 13 of this embodiment extends from the central portion 12 to the first main groove 3 . Similarly, the second outer portion 14 extends from the central portion 12 to the second main groove 4 .

The axial length L3 of the first outer portion 13 and the axial length L4 of the second outer portion 14 are each preferably smaller than the axial length of the central portion 12 . In this embodiment, the length L3 of the first outer portion 13 and the length L4 of the second outer portion 14 are 0.10 to 0.30 times the axial width W2 of the intermediate land portion 7. . Such first outer portion 13 and second outer portion 14 can suppress uneven wear near both ends of the intermediate sipe 10 .

It is desirable that the maximum angle θ2 of the first outer portion 13 and the second outer portion 14 with respect to the tire axial direction is, for example, less than 45°. Specifically, the angle θ2 between the first outer portion 13 and the second outer portion 14 is, for example, 10 to 30 degrees. Preferably, the angle θ2 of the first outer portion 13 and the second outer portion 14 is the same as or smaller than the angle θ1 of the central portion 12 with respect to the axial direction of the tire. As a result, uneven wear near both ends of the intermediate sipe 10 is further suppressed.

In this embodiment, it is desirable that the angles of the first outer portion 13 and the second outer portion 14 with respect to the axial direction of the tire gradually increase from the center portion 12 outward in the axial direction of the tire. This further reduces the impact sound when the end portion of the intermediate sipe 10 touches the ground, thereby improving the noise performance.

One pitch length P1 in the tire circumferential direction between two intermediate sipes 10 adjacent in the tire circumferential direction is, for example, equal to or smaller than the axial width W2 of the intermediate land portion 7 . Specifically, the one-pitch length P1 of the intermediate sipe 10 is 0.50 to 1.00 times the width W2 of the intermediate land portion 7 . Moreover, it is desirable that the one-pitch length P1 of the intermediate sipe 10 is larger than the groove width of the first main groove 3, for example. Arrangement of the intermediate sipes 10 in this manner helps to suppress excessive reduction in rigidity of the intermediate land portion 7 .

FIG. 7 shows a CC line cross-sectional view of the intermediate sipe 10 of FIG. As shown in FIG. 7, the intermediate sipe 10 includes, for example, a body portion 10a and a shallow portion 10b having a depth smaller than that of the body portion 10a. The shallow bottom portion 25b of the present embodiment is formed, for example, in each of the first outer portion 13 and the second outer portion 14 (shown in FIG. 6) of the intermediate sipe 10. As shown in FIG.

The axial length L11 of the shallow portion 10b of the intermediate sipe 10 is preferably smaller than the axial length L10 (shown in FIG. 5) of the shallow portion 25b of the outer sipe 25, for example. Moreover, the length L11 of the shallow portion 10b of the intermediate sipe 10 is preferably smaller than the axial length L9 (shown in FIG. 3) of the shallow portion 21b of the inner sipe 21, for example. Specifically, the length L11 of the shallow portion 10b of the intermediate sipe 10 is 0.40 to 0.60 times the length L9 of the shallow portion 21b of the inner sipe 21 . Such outer sipes 25 serve to improve steering stability and noise performance in a well-balanced manner.

In order to improve wet performance and steering stability in a well-balanced manner, the depth d6 of the shallow bottom portion 10b of the intermediate sipe 10 is, for example, 0.30 to 0.60 times the depth d5 of the main body portion 10a of the intermediate sipe 10. It is desirable to have

Only the intermediate sipe 10 described above is arranged in the intermediate land portion 7 of the present embodiment, and no grooves or sipes other than this are arranged. Such an intermediate land portion 7 has high rigidity and is useful for exhibiting excellent steering stability.

As shown in FIG. 1, the tire 1 of the present embodiment is suitable for use in small-displacement passenger cars such as light cars. Therefore, it is desirable that the tread width TW is, for example, 90-120 mm.

Although the tire according to the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be implemented in various ways.

A pneumatic tire of size 155/65R14 having the basic tread pattern shown in FIG. As a comparative example, a trial tire having the tread pattern shown in FIG. 8 was produced. As shown in FIG. 8, the outer land portion a of the tire of the comparative example is provided with first lateral grooves b extending from the outer tread edge To and discontinued within the outer land portion a. The first lateral grooves b have the same groove width and length as the outer lateral grooves 23 of FIG. Further, the inner land portion c of the tire of the comparative example is provided with a second lateral groove e extending from the second main groove d and discontinued within the inner land portion c. The second lateral groove e in FIG. 8 has the same groove width and length as the inner lateral groove 20 in FIG. The tread pattern of the comparative example is substantially the same as that of FIG. 1 except for the above points. Each test tire was tested for handling stability, noise performance and wet performance. Common specifications and test methods for each test tire are as follows.
Rim: 14 x 4.5J
Tire internal pressure: 240kPa
Test vehicle: 660cc displacement, front-wheel drive Tire mounting position: All wheels

<Steering stability>
When the test vehicle was run on a circuit, the steering stability during lane changes and turns was evaluated by the driver's sensory perception. This evaluation was conducted by running the test vehicle in a speed range including a low/medium speed range of 40 to 80 km/h and a high speed range of 100 to 120 km/h. The results are scored with the comparative example being 100, and the larger the number, the better the steering stability.

<Noise performance>
The test vehicle was run at 40 to 100 km/h on a dry road surface including unevenness, and the maximum sound pressure of noise (100 to 160 Hz) inside the vehicle was measured at this time. The results are indexed with the sound pressure of the comparative example being 100, and the smaller the numerical value, the smaller the noise inside the vehicle and the better the noise performance.

<Wet Performance>
Performance when the test vehicle was driven on a wet road surface was evaluated by the driver's sensory perception. The results are scored with the comparative example being 100, and the larger the number, the better the wet performance.
The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that the tires of Examples had improved steering stability, noise performance and wet performance.

2 tread portion 3 first main groove 4 second main groove 6 outer land portion 8 inner land portion 20 inner lateral groove 23 outer lateral groove To outer tread edge Ti inner tread edge

Claims (12)

A tire for which the mounting direction to the vehicle is specified,
a tread portion defining an outer tread end positioned on the outer side of the vehicle when mounted on a vehicle and an inner tread end positioned on the inner side of the vehicle when mounted on the vehicle;
The tread portion is
a first main groove extending continuously in the tire circumferential direction between the outer tread edge and the tire equator;
a second main groove extending continuously in the tire circumferential direction between the inner tread edge and the tire equator;
It is composed of three land portions divided by the first main groove and the second main groove,
The land part
an outer land portion partitioned between the outer tread edge and the first main groove;
an inner land portion divided between the second main groove and the inner tread edge;
The outer land portion is provided with a plurality of outer lateral grooves extending from the first main groove and interrupted within the outer land portion,
the inner land portion is provided with a plurality of inner lateral grooves extending from the inner tread end and discontinuous within the inner land portion ;
The maximum angle of the groove centerline of the outer lateral groove with respect to the tire axial direction is greater than the maximum angle of the groove centerline of the inner lateral groove with respect to the tire axial direction,
tire. The tire according to claim 1, wherein the axial width of the outer land portion and the axial width of the inner land portion are each 0.25 to 0.35 times the tread width. The tire according to claim 1 or 2, wherein the axial width of the outer land portion is the same as the axial width of the inner land portion. The tire according to any one of claims 1 to 3, wherein the land ratio of the outer land portion is larger than the land ratio of the inner land portion. The tire according to claim 4, wherein the land ratio of the outer land portion is 1.03 to 1.08 times the land ratio of the inner land portion. The tire according to any one of claims 1 to 5, wherein the groove width of the outer lateral grooves is smaller than the groove width of the inner lateral grooves. The tire according to claim 6, wherein the groove width of the outer lateral grooves is 0.40 to 0.60 times the groove width of the inner lateral grooves. The angle of the groove center line of the inner lateral groove with respect to the tire axial direction is 0 to 10°,
The tire according to claim 1, wherein the angle of the groove centerline of the outer lateral groove with respect to the tire axial direction is 15 to 25°. The tire according to any one of claims 1 to 8, wherein the outer lateral groove is discontinued on the first main groove side of the center position of the outer land portion in the tire axial direction. The tire according to claim 9, wherein the axial length of the outer lateral groove is 0.30 to 0.40 times the axial width of the outer land portion. The tire according to any one of claims 1 to 10, wherein the inner lateral groove is discontinued on the second main groove side of the center position of the inner land portion in the tire axial direction. The tire according to claim 11, wherein the axial length of the inner lateral groove is 0.60 to 0.70 times the axial width of the inner land portion.

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