CN111038180B

CN111038180B - Tyre for vehicle wheels

Info

Publication number: CN111038180B
Application number: CN201910916500.2A
Authority: CN
Inventors: 宇治川数马
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2018-10-12
Filing date: 2019-09-26
Publication date: 2023-03-28
Anticipated expiration: 2039-09-26
Also published as: DE102019126845A1; JP2020059459A; JP7155847B2; CN111038180A

Abstract

The invention provides a tire capable of improving steering stability and noise performance. A tire specified in a mounting direction toward a vehicle has a tread portion (2) in which an outer tread end (To) and an inner tread end (Ti) are selected, the tread portion (2) having a first main groove (3), a second main groove (4), an outer block portion (6) divided between the outer tread end (To) and the first main groove (3), and an inner block portion (8) divided between the second main groove (4) and the inner tread end (Ti), a plurality of outer lateral grooves (23) extending from the first main groove (3) and interrupted in the outer block portion (6) being provided on the outer block portion (6), and a plurality of inner lateral grooves (20) extending from the inner tread end (Ti) and interrupted in the inner block portion (8) being provided on the inner block portion (8).

Description

Tyre for vehicle wheels

Technical Field

The present invention relates to a tire, and more particularly to a tire whose mounting direction toward a vehicle is specified.

Background

Patent document 1 listed below proposes a tire whose mounting direction toward a vehicle is specified. The tread portion of the tire is divided into three block portions by two circumferential main grooves. In order to improve steering stability, the tire is configured such that the widest block portion having the widest width among the three block portions is located on the vehicle outer side when mounted on the vehicle.

Patent document 1: japanese laid-open patent publication No. 2015-217907

Disclosure of Invention

The tire of patent document 1 still has room for further improvement in noise performance and wet skid performance.

The present invention has been made in view of the above circumstances, and a main object thereof is to provide a tire capable of improving steering stability, noise performance, and wet performance in a balanced manner.

The present invention is a tire having a tread portion in which an outer tread end and an inner tread end are selected, the outer tread end being located on an outer side of a vehicle when the tire is mounted on the vehicle, the inner tread end being located on an inner side of the vehicle when the tire is mounted on the vehicle, the tire having: a first main groove continuously extending in the tire circumferential direction between the outer tread end and the tire equator; a second main groove extending continuously in the tire circumferential direction between the inner tread end and the tire equator; an outer block portion divided between the outer tread end and the first main groove; and an inner block portion divided between the second main groove and the inner tread end, the outer block portion being provided with a plurality of outer lateral grooves extending from the first main groove and interrupted in the outer block portion, and the inner block portion being provided with a plurality of inner lateral grooves extending from the inner tread end and interrupted in the inner block portion.

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

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

In the tire of the present invention, it is preferable that the outer block portion has a ground contact ratio larger than that of the inner block portion.

In the tire of the present invention, it is preferable that the ground contact ratio of the outer block portion is 1.03 to 1.08 times the ground contact ratio of the inner block portion.

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

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

In the tire of the present invention, it is preferable that an angle of the outer lateral groove with respect to the tire axial direction is larger than an angle of the inner lateral groove with respect to the tire axial direction.

In the tire according to 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 °, and the angle of the outer lateral groove with respect to the tire axial direction is 15 to 25 °.

In the tire of the present invention, it is preferable that the outer lateral groove is interrupted on a side closer to the first main groove than a center position of the outer block portion in the tire axial direction.

In the tire of the present invention, it is preferable that the length of the outer lateral groove in the tire axial direction is 0.30 to 0.40 times the width of the outer block portion in the tire axial direction.

In the tire of the present invention, it is preferable that the inner lateral groove is interrupted on a side closer to the second main groove than a center position of the inner block portion in the tire axial direction.

In the tire according to the present invention, it is preferable that the length of the inner lateral groove in the tire axial direction is 0.60 to 0.70 times the width of the inner block portion in the tire axial direction.

In the tire of the present invention, it is preferable that the tread portion is constituted by three block portions defined by the first main groove and the second main groove.

The tire tread portion of the present invention includes: a first main groove continuously extending in the tire circumferential direction between an outer tread end and a tire equator; a second main groove extending continuously in the tire circumferential direction between an inner tread end and the tire equator, an outer block portion divided between the outer tread end and the first main groove; and an inner block portion divided between the second main groove and the inner tread end.

The outer block portion of the present invention is provided with a plurality of outer lateral grooves extending from the first main groove and interrupted in the outer block portion. The outer lateral grooves exhibit excellent drainage performance together with the first main grooves. Further, since the outer main groove moderately reduces the rigidity in the vicinity of the first main groove of the outer block portion, it is advantageous to reduce the flapping sound when the first main groove side end edge of the outer block portion contacts the ground. Further, since the outer lateral groove is interrupted in the outer block portion, the rigidity in the vicinity of the outer tread end of the outer block portion can be maintained. Therefore, the outer block portion can be prevented from being excessively deformed during rotation, and steering stability can be maintained.

The inner block portion of the present invention is provided with a plurality of inner lateral grooves extending from the inner tread end and interrupted in the inner block portion. Since a high ground contact pressure tends to act on the inner block portion during straight traveling, the inner lateral groove can exhibit high drainage performance during straight traveling. Further, the rigidity of the inner block portion in the vicinity of the inner tread end is appropriately reduced by the inner lateral groove, so that the flapping sound when the inner tread end contacts the ground can be reduced. Further, since the inner lateral groove is interrupted in the inner block portion, high rigidity on the second main groove side of the inner block portion is maintained. This can prevent a sudden deformation of the inner block portion when the center of the tire ground contact surface moves toward the outer block portion side at the time of rotation. Therefore, the driving feeling at the time of rotation becomes stable, so that excellent steering stability can be obtained.

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

Drawings

Fig. 1 is a development view of a tread portion of a tire according to an embodiment of the present invention.

Fig. 2 is an enlarged view of the inner block portion of fig. 1.

Fig. 3 isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A of fig. 2.

Fig. 4 is an enlarged view of the outer block portion of fig. 1.

Fig. 5 is a sectional view taken along line B-B of fig. 4.

Fig. 6 is an enlarged view of the middle block portion of fig. 1.

Fig. 7 is a sectional view taken along line C-C of fig. 6.

Fig. 8 is a developed view of a tread portion of a tire of a comparative example.

Description of the reference numerals

2. Tread portion

3. First main groove

4. Second main groove

6. Outer pattern block part

8. Inner pattern block part

20. Inner side transverse groove

23. Lateral transverse groove

To outer tread end

Inner tread end of Ti

Detailed Description

An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 shows a development view of a tread portion 2 of a tire 1 of the present embodiment. For example, the tire 1 of the present embodiment is configured as a pneumatic tire for a passenger vehicle. The tire 1 of the present embodiment is preferably used as a tire for a small automobile in particular.

As shown in fig. 1, for example, the mounting direction of the tire 1 of the present embodiment to the vehicle is specified. For example, the mounting direction to the vehicle may be indicated by characters, graphics, or the like on a sidewall portion (not shown) of the tire 1. When the tire 1 is mounted on a vehicle, the right side of fig. 1 corresponds to the vehicle inside, and the left side of fig. 1 corresponds to the vehicle outside.

Since the mounting direction toward the vehicle is specified, an inner tread end Ti located on the vehicle inner side when mounted To the vehicle and an outer tread end To located on the vehicle outer side when mounted To the vehicle are selected on the tread portion 2.

In the case of a pneumatic tire, the inner tread end Ti and the outer tread end To are the ground contact positions on the outermost sides in the tire axial direction when a normal load is applied To the tire 1 in a normal state and the camber angle is 0 ° and ground contact is made in a planar manner. The normal state is a state in which the tire is mounted on a normal rim and filled with normal internal pressure and no load. In the present specification, the dimensions and the like of each portion of the tire are values measured in a normal state, unless otherwise specified.

The "regular Rim" is a Rim specified for each tire in a specification system including a specification under which the tire conforms, and is, for example, "standard Rim" in case of JATMA, "Design Rim" in case of TRA, and "Measuring Rim" in case of ETRTO.

The "normal internal PRESSURE" is an air PRESSURE specified for each TIRE in a specification system including a specification under which the TIRE is compliant, and is "maximum air PRESSURE" in the case of JATMA, the maximum value described in the table "TIRE LOAD conditions AT TIREs PRESSURES associated with TRA, and" INFLATION PRESSURE "in the case of ETRTO.

The "normal LOAD" is a LOAD specified for each TIRE in a specification system including a specification under which the TIRE is based, and is "maximum LOAD CAPACITY" in the case of JATMA, a maximum value described in a table "TIRE LOAD limit AT variables TIRE stability requirements" in the case of TRA, and a "LOAD CAPACITY" in the case of ETRTO.

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

The first main groove 3 and the second main groove 4 extend continuously in the tire circumferential direction with a large width and depth to discharge water on the road surface toward the rear of the tire. In a preferred embodiment, each main groove has a groove width and depth of 5mm or more, more preferably 6mm 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 a distance in the tire axial direction from the inner tread end Ti To the outer tread end To in the normal state. For example, each main groove extends linearly in the tire circumferential direction. In another embodiment, each main groove may be non-linear, such as a zigzag or wavy groove.

For example, the first main groove 3 is arranged between the tire equator C and the outer tread end To. For example, the second main groove 4 is arranged between the tire equator C and the inner tread end Ti. For example, the distance L1 in the tire axial direction from the tire equator C to the groove center line of the first main groove 3 or the second main groove 4 is preferably 0.10 to 0.20 times the tread width TW. In a preferred embodiment, the difference between the distance in the tire axial direction from the tire equator C to the groove center line of the first main groove 3 and the distance in the tire axial direction 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.

For example, the tread portion 2 is constituted by three block portions divided by the first main groove 3 and the second main groove 4. Specifically, the tread portion 2 is constituted by an outer block portion 6, an intermediate block portion 7, and an inner block portion 8. The outer block portion 6 is divided between the outer tread end To and the first main groove 3. The intermediate block portion 7 is divided between the first main groove 3 and the second main groove 4. The inner block portion 8 is divided between the inner tread end Ti and the second main groove 4. The tread portion 2 of the present embodiment has an asymmetric pattern with respect to the tire equator C.

In the present invention, the outer block 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 interrupted in the outer block portion 6. The outer lateral grooves 23 exhibit excellent drainage performance together with the first main grooves 3. Further, the outer lateral grooves 23 moderately reduce the rigidity of the outer block portion 6 in the vicinity of the first main groove 3, and therefore contribute to reducing flapping sound when the edge of the outer block portion 6 on the first main groove 3 side comes into contact with the ground. Further, since the outer lateral grooves 23 are interrupted in the outer block portions 6, the rigidity in the vicinity of the outer tread ends To of the outer block portions 6 can be maintained. Thus, the outer block portion 6 can be prevented from being excessively deformed at the time of rotation, and steering stability can be maintained.

A plurality of inner lateral grooves 20 are provided in the inner block portion 8. The inner lateral groove 20 extends from the inner tread end Ti and is interrupted in the inner block portion 8. Since a high ground contact pressure tends to act on the inner block portion 8 during straight running, the inner lateral grooves 20 can exhibit a high drainage performance during straight running. Further, the inner lateral grooves 20 moderately reduce the rigidity of the inner block portion 8 in the vicinity of the inner tread end Ti, and thus the flapping sound when the inner tread end Ti contacts the ground can be reduced. Further, since the inner lateral groove 20 is interrupted in the inner block portion 8, high rigidity of the inner block portion 8 on the second main groove 4 side is maintained. This can prevent a sudden deformation of the inner block portion 8 when the ground contact surface center of the tire moves toward the outer block portion 6 side at the time of rotation. Therefore, the driving feeling at the time of rotation becomes stable, so that excellent steering stability can be obtained.

The detailed structure of each part will be described below. Fig. 2 shows an enlarged view of the inner block portion 8. As shown in fig. 2, for example, the width W3 of the inner block portion 8 in the tire axial direction is preferably 0.25 to 0.35 times the tread width TW (the same applies to fig. 1).

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

For example, the length L5 of the inner lateral groove 20 in the tire axial direction is 0.30 to 0.70 times, more preferably 0.60 to 0.70 times, the width W3 of the inner block portion 8 in the tire axial direction. For example, it is more preferable that the inner lateral groove 20 is interrupted on the side closer to the second main groove 4 than the center position of the inner block portion 8 in the tire axial direction.

For example, the inner lateral grooves 20 are arranged at an angle θ 3 of 0 to 10 ° with respect to the tire axial direction. In a preferred embodiment, the angle of the inner lateral groove 20 with respect to the tire axial direction gradually increases toward the tire axial direction.

For example, it is preferable that the 1-pitch length P2 in the tire circumferential direction of two inner lateral grooves 20 adjacent in the tire circumferential direction be greater than the width W3 in the tire axial direction of the inner block portion 8. Specifically, the 1-pitch length P2 of the inner lateral groove 20 is preferably 1.05 to 1.15 times the width W3 of the inner block portion 8. This arrangement of the inner lateral grooves 20 can improve the steering stability and the wet skid performance in a well-balanced manner.

For example, a plurality of inner sipes 21 are provided in the inner block portion 8 of the present embodiment. Further, in the present specification, "sipe" means a cut groove having a width of less than 1.5 mm. In a preferred embodiment, the sipe has a width of 1.0mm or less.

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

For example, the inside sipes 21 and the inside lateral grooves 20 are inclined in the same direction with respect to the tire axial direction. For example, the inner sipe 21 has an angle θ 4 of 5 to 15 ° with respect to the tire axial direction. The angle of the inside sipe 21 of the present embodiment with respect to the tire axial direction gradually increases toward the inside in the tire axial direction. Further, the maximum angle of the inside sipes 21 with respect to the tire axial direction is larger than the maximum angle of the inside lateral grooves 20 with respect to the tire axial direction. Such an inside sipe 21 can provide a frictional force in the tire axial direction when running on a wet road surface.

For example, it is preferable that the 1-pitch length P3 in the tire circumferential direction of two adjacent inner sipes 21 in the tire circumferential direction be greater than the width W3 in the tire axial direction of the inner block portion 8. Specifically, the 1-pitch length P3 of the inner sipe 21 is preferably 1.05 to 1.15 times the width W3 of the inner block portion 8. In the present embodiment, the inner lateral grooves 20 and the inner sipes 21 are arranged at the same 1-pitch length.

FIG. 3 illustratesbase:Sub>A cross-sectional view taken along line A-A of the inboard sipe 21 of FIG. 2. As shown in FIG. 3, for example, the inboard sipe 21 includes a body portion 21a and a shallow bottom portion 21b having a depth less than the body portion 21 a. Such a sipe 21 can maintain the rigidity of the inner block portion 8, so that the steering stability can be further improved.

For example, the shallow bottom 21b is preferably provided on the side closer to the tire equator C than the interrupted end of the inner lateral groove 20 (shown in fig. 2). Preferably, the shallow bottom portion 21b does not overlap an imaginary extension of the inner lateral groove 20 in parallel in the tire circumferential direction. For example, the shallow bottom portion 21b of the present embodiment is provided at the end portion of the inner sipe 21 on the tire equator C side. Such a shallow bottom portion 21b can maintain high rigidity of the inner block portion 8 on the second main groove 4 side, so that steering stability can be further improved.

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

As shown in fig. 2, it is preferable that no lateral groove extending from the inner tread end Ti to the second main groove 4 is provided in the inner block portion 8. Such an inner block portion 8 has high rigidity and can exhibit excellent steering stability.

Fig. 4 shows an enlarged view of the outer block portion 6. As shown in fig. 4, for example, the width W5 of the outer block portion 6 in the tire axial direction is preferably 0.25 to 0.35 times the tread width TW. In a more preferable mode, the width W5 of the outer block portion 6 is the same as the width W3 of the inner block portion 8 in the tire axial direction.

For example, the groove width W7 of the outer lateral grooves 23 is preferably smaller than the groove width W4 of the inner lateral grooves 20 (as shown in fig. 2). 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. This makes it possible to whiten the pumping noise of the inner lateral grooves 20 and the outer lateral grooves 23, and thus to obtain excellent noise performance. Also, such outer lateral grooves 23 can improve the steering stability and the wet skid performance in a well-balanced manner.

For example, the length L8 of the outer lateral groove 23 in the tire axial direction is 0.25 to 0.45 times, more preferably 0.30 to 0.40 times, the width W5 of the outer block portion 6 in the tire axial direction. For example, the outer lateral groove 23 is preferably interrupted on the first main groove 3 side of the center position of the outer block portion 6 in the tire axial direction.

Preferably, the angle θ 7 of the outer lateral groove 23 with respect to the tire axial direction is larger than the angle θ 3 of the inner lateral groove 20 with respect to the tire axial direction. Specifically, for example, the angle θ 7 of the outer lateral groove 23 with respect to the tire axial direction is 15 to 25 °.

For example, it is preferable that the 1-pitch length P6 in the tire circumferential direction of the two outer lateral grooves 23 adjacent in the tire circumferential direction be larger than the width W5 in the tire axial direction of the outer block portion 6. Specifically, the 1-pitch length P6 of the outer lateral groove 23 is 1.05 to 1.15 times the width W5 of the outer block portion 6. This arrangement of the outer lateral grooves 23 can improve the steering stability and the wet skid performance in a well-balanced manner.

For example, a plurality of outer sipes 25 are provided in the outer block portion 6 of the present embodiment. For example, the outside sipe 25 extends from the first main groove 3 To the outside tread end To. For example, in the present embodiment, the outer sipes 25 and the outer lateral grooves 23 are alternately arranged in the tire circumferential direction.

For example, the outer sipes 25 and the outer lateral grooves 23 are inclined in the same direction with respect to the tire axial direction. For example, the angle θ 8 of the outer sipe 25 with respect to the tire axial direction is 10 to 25 °. The angle of the outer sipe 25 of the present embodiment with respect to the tire axial direction gradually increases toward the tire axial direction inner side. Also, 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 outer sipes 25 can provide a frictional force in the tire axial direction when running on a wet road.

For example, it is preferable that the 1-pitch length P7 in the tire circumferential direction of two outer sipes 25 adjacent in the tire circumferential direction be larger than the width W5 in the tire axial direction of the outer block portion 6. Specifically, the 1-pitch length P7 of the outer sipe 25 is 1.05 to 1.15 times the width W5 of the outer block portion 6. This arrangement of the outside sipes 25 can improve the steering stability and the wet skid performance in a well-balanced manner.

FIG. 5 illustrates a cross-sectional view of the outboard sipe 25 of FIG. 4 along line B-B. As shown in FIG. 5, for example, the lateral sipe 25 includes a body portion 25a and a shallow bottom portion 25b having a depth less than the body portion 25 a. Such an outer sipe 25 can maintain the rigidity of the outer block portion 6, and can further improve the steering stability.

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

For example, the shallow bottom portion 25b of the outer sipe 25 preferably has a length L10 in the tire axial direction that is greater than the length L9 in the tire axial direction of the shallow bottom portion 21b of the inner sipe 21 (as shown in FIG. 3). Specifically, the length L10 of the shallow bottom portion 25b of the outer sipe 25 is 1.30 to 2.00 times the length L9 of the shallow bottom portion 21b of the inner sipe 21. Such an outer sipe 25 causes an appropriate difference in rigidity between the outer block portion 6 and the inner block portion 8. This makes the driving feeling linear when the ground contact surface center of the tire moves toward the outer block portion side at the time of rotation, so that excellent steering stability can be obtained. Further, for example, the length of each shallow bottom portion may be measured in a region other than the depth change portion on the main body portion side.

In order to improve the wet skid performance and the steering stability in a well-balanced manner, for example, it is preferable that the depth d4 of the shallow bottom portion 25b of the outside sipe 25 is 0.30 to 0.60 times the depth d3 of the body portion 25a of the outside sipe 25.

As shown in fig. 4, it is preferable that no lateral groove extending from the outer tread end To the first main groove 3 is provided in the outer block portion 6. Such an outer block portion 6 has high rigidity and can exert excellent steering stability.

Preferably, the ground contact ratio of the outer block portion 6 is larger than that of the inner block portion 8. Specifically, the ground contact ratio of the outer block portion 6 is 1.03 to 1.08 times the ground contact ratio of the inner block portion 8. Such an outer block portion 6 can further improve steering stability. In the present specification, the "ground contact ratio" is a ratio Sb/Sa of an actual total ground contact area Sb to a total area Sa of virtual ground contact surfaces to which all the grooves and sipes are added.

Fig. 6 shows an enlarged view of the intermediate block portion 7. As shown in fig. 6, for example, the width W2 of the intermediate block portion 7 in the tire axial direction is preferably 0.15 to 0.25 times the tread width TW.

For example, it is preferable that the middle block portion 7 be located on the tire equator C. In the present embodiment, the center position of the intermediate block portion 7 in the tire axial direction is arranged in the vicinity of the tire equator C. More specifically, the tire axial direction distance between the tire equator C and the tire axial direction center position of the intermediate block portion 7 is less than 10% of the tire axial direction width W2 of the intermediate block portion 7.

An intermediate sipe 10 that completely crosses the intermediate block portion 7 is provided in the intermediate block portion 7. The intermediate sipe 10 has a central portion 12, a first outer side portion 13 and a second outer side portion 14. The center 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 side portion 14 is inclined in the opposite direction to the central portion 12 on the side of the second main groove 4.

This intermediate sipe 10 can prevent the entire edge from being simultaneously grounded, and can reduce flapping noise when the edge is grounded.

Further, when a ground contact pressure acts on the intermediate block portion 7 to close the intermediate sipe 10, the contacting sipe walls of the intermediate sipe 10 engage with each other, thereby preventing shear deformation of the intermediate block portion 7 bounded by the intermediate sipe 10. Thus, excellent steering stability can be obtained.

For example, the intermediate sipe 10 extends in a smooth curve and forms a cycle of a wave. But is not limited in this manner, and for example, a portion of the intermediate sipe 10 may also extend linearly.

The center portion 12 of the present embodiment crosses the tire equator C. The center portion 12 crosses the center position of the intermediate block portion 7 in the tire axial direction. For example, the central portion 12 includes a portion 12a extending in a straight line, and the straight line portion 12a crosses the tire equator C. The center portion 12 includes a portion that is oriented toward the first outer side portion 13 or the second outer side portion 14 side and that gradually decreases in angle with respect to the tire axial direction.

For example, the length L2 of the center portion 12 in the tire axial direction is preferably 0.50 times or more the width W2 of the intermediate block portion 7 in the tire axial direction. Specifically, for example, the length L2 of the center portion 12 is 0.50 to 0.70 times the width W2 of the middle block portion 7. Such a central portion 12 can not only prevent uneven wear of the intermediate block portion 7, but also exhibit the above-described effects.

For example, the maximum angle θ 1 of the central portion 12 with respect to the tire axial direction is preferably smaller than 45 °. Specifically, the angle θ 1 of the central portion 12 is preferably 10 to 30 °. Such a center portion 12 can improve noise performance and steering stability in a balanced manner.

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

Preferably, the length L3 of the first outer side portion 13 in the tire axial direction and the length L4 of the second outer side portion 14 in the tire axial direction are each smaller than the length of the center portion 12 in the tire axial direction. In the present embodiment, the length L3 of the first outer side portion 13 and the length L4 of the second outer side portion 14 are 0.10 to 0.30 times the width W2 of the middle block portion 7 in the tire axial direction. Such first and second

outer side portions

13 and 14 can prevent partial wear near both ends of the intermediate sipe 10.

For example, it is preferable that the maximum angle θ 2 of the first outer side portion 13 and the second outer side portion 14 with respect to the tire axial direction is smaller than 45 °. Specifically, for example, the angle θ 2 between the first outer side portion 13 and the second outer side portion 14 is 10 to 30 °. In a preferred embodiment, said angle θ 2 of the first and second

outer side portions

13, 14 is equal to or smaller than the angle θ 1 of the central portion 12 with respect to the axial direction of the tire. This can further prevent partial wear near both ends of the intermediate sipe 10.

In the present embodiment, it is preferable that the angles of the first outer side portion 13 and the second outer side portion 14 with respect to the tire axial direction gradually increase from the center portion 12 toward the tire axial direction outer side, respectively. This makes the slapping sound when the end of the intermediate sipe 10 is grounded further smaller, thereby improving the noise performance.

For example, the 1-pitch length P1 in the tire circumferential direction of two intermediate sipes 10 adjacent in the tire circumferential direction is the same as the width W2 of the intermediate block portion 7 in the tire axial direction, or is smaller than the width W2. Specifically, the 1-pitch length P1 of the intermediate sipe 10 is 0.50 to 1.00 times the width W2 of the intermediate block portion 7. Also, for example, it is preferable that the 1-pitch length P1 of the intermediate sipe 10 is larger than the groove width of the first main groove 3. Such a position of the intermediate sipe 10 is advantageous in preventing the intermediate block portion 7 from being excessively reduced in rigidity.

FIG. 7 illustrates a cross-sectional view of the intermediate sipe 10 of FIG. 6 taken along line C-C. As shown in FIG. 7, for example, the intermediate sipe 10 includes a body portion 10a and a shallow bottom portion 10b having a depth less than the body portion 10 a. For example, the shallow bottom portions 10b of the present embodiment are formed on the first and second outer side portions 13 and 14 (shown in fig. 6) of the intermediate sipe 10, respectively.

For example, the shallow bottom portion 10b of the middle sipe 10 preferably has a tire axial length L11 that is less than the tire axial length L10 of the shallow bottom portion 25b of the outer sipe 25 (as shown in FIG. 5). Also, for example, it is preferable that the length L11 of the shallow bottom portion 10b of the intermediate sipe 10 be less than the tire axial length L9 of the shallow bottom portion 21b of the inner sipe 21 (as shown in FIG. 3). Specifically, the length L11 of the shallow bottom portion 10b of the intermediate sipe 10 is 0.40 to 0.60 times the length L9 of the shallow bottom portion 21b of the inner sipe 21. Such an outside sipe 25 contributes to a balanced improvement in steering stability and noise performance.

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

In the intermediate block portion 7 of the present embodiment, only the intermediate sipe 10 is disposed, and the other grooves and sipes are not disposed. Such a middle block portion 7 has high rigidity, and thus is advantageous in exerting excellent steering stability.

As shown in fig. 1, the tire 1 of the present embodiment can be suitably used for a small-displacement passenger vehicle such as a small-sized automobile. Therefore, for example, the tread width TW is preferably 90 to 120mm.

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

[ examples ] A method for producing a compound

Pneumatic tires having a size of 155/65R14 of the basic tread pattern of FIG. 1 were prototyped according to the specifications of Table 1. A tire having a tread pattern shown in fig. 8 was prototyped as a comparative example. As shown in fig. 8, the tire outer block portion a of the comparative example is provided with a first lateral groove b extending from the outer tread end To and interrupted in the outer block portion a. The first transverse grooves b have the same groove width and length as the outer transverse grooves 23 of fig. 1. Further, the inner block 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 interrupted in the inner block portion c. The second transverse slot e of fig. 8 has the same slot width and length as the inner transverse slot 20 of fig. 1. Except for the above points, the tread pattern of the comparative example is substantially the same as the tread pattern of fig. 1. The steering stability, noise performance and wet skid performance of each test tire were tested. The common specification and test method of each test tire are as follows.

Rim: 14X 4.5J

Tire internal pressure: 240kPa

Testing the vehicle: front wheel drive vehicle with air displacement of 660cc

Tire mounting position: all-wheel

< steering stability >

The steering stability at lane change and rotation of the test vehicle was evaluated on the basis of the driver's sense of performance. The evaluation was carried out by running the test vehicle in a speed region including a low and medium speed region of 40 to 80km/h and a high speed region of 100 to 120 km/h. The result is a score of 100 in comparative example, and a larger numerical value indicates more excellent operation stability.

< noise Performance >

The test vehicle was run on a dry road surface including irregularities at a speed of 40 to 100km/h, and the maximum sound pressure of the in-vehicle noise (100 to 160 Hz) at that time was measured. The result is a score of 100 for the sound pressure of the comparative example, and the smaller the numerical value, the smaller the noise in the vehicle, the better the noise performance.

< Wet skid Property >

The performance of the test vehicle was evaluated on a wet road surface according to the sensory evaluation of the driver. The results are given by a score of 100 in comparative example, and the larger the numerical value, the more excellent the wet skid performance.

The test results are shown in table 1.

[ TABLE 1 ]

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The test results can confirm that the tires of the examples improve steering stability, noise performance, and wet performance.

Claims

1. A tire, a mounting direction toward a vehicle being specified, characterized in that,

a tread portion having selected outer and inner tread ends, wherein the outer tread end is located on an outer side of the vehicle when installed thereto and the inner tread end is located on an inner side of the vehicle when installed thereto,

the tread portion has:

a first main groove continuously extending in the tire circumferential direction between the outer tread end and the tire equator;

a second main groove that extends continuously in the tire circumferential direction between the inner tread end and the tire equator;

an outer block portion divided between the outer tread end and the first main groove; and

an inner block portion divided between the second main groove and the inner tread end,

a plurality of outer lateral grooves extending from the first main groove and interrupted in the outer block portion are provided on the outer block portion,

a plurality of inner lateral grooves extending from the inner tread end and interrupted in the inner block portion are provided on the inner block portion,

the tread portion is constituted by three block portions divided by the first main groove and the second main groove,

the distance in the tire axial direction from the tire equator to the groove center line of the first main groove or the second main groove is 0.10 to 0.20 times the tread width TW,

the difference between the distance in the tire axial direction from the tire equator to the groove center line of the first main groove and the distance in the tire axial direction from the tire equator to the groove center line of the second main groove is less than 3% of the tread width TW.

2. The tire according to claim 1,

the width of the outer block portion in the tire axial direction and the width of the inner block portion in the tire axial direction are respectively 0.25 to 0.35 times of the tread width.

3. Tire according to claim 1 or 2,

the width of the outer block portion in the tire axial direction is the same as the width of the inner block portion in the tire axial direction.

4. Tire according to claim 1 or 2,

the outer block portion has a ground contact ratio greater than that of the inner block portion.

5. Tire according to claim 4,

the ground contact ratio of the outer block portion is 1.03 to 1.08 times the ground contact ratio of the inner block portion.

6. Tire according to claim 1 or 2,

the groove width of the outer lateral groove is smaller than that of the inner lateral groove.

7. The tire according to claim 6,

the groove width of the outer lateral groove is 0.40 to 0.60 times of the groove width of the inner lateral groove.

8. Tire according to claim 1 or 2,

the angle of the outer lateral groove with respect to the tire axial direction is larger than the angle of the inner lateral groove with respect to the tire axial direction.

9. The tire according to claim 8,

the angle of the inner lateral groove relative to the axial direction of the tire is 0-10 degrees,

the angle of the outer lateral groove relative to the axial direction of the tire is 15-25 degrees.

10. Tire according to claim 1 or 2,

the outer lateral groove is interrupted on a side closer to the first main groove than a center position of the outer block portion in the tire axial direction.

11. The tire according to claim 10,

the length of the outer lateral groove in the tire axial direction is 0.30 to 0.40 times the width of the outer block portion in the tire axial direction.

12. Tire according to claim 1 or 2,

the inner lateral groove is interrupted on a side closer to the second main groove than a center position of the inner block portion in the tire axial direction.

13. The tire according to claim 12,

the length of the inner lateral groove in the tire axial direction is 0.60 to 0.70 times the width of the inner block portion in the tire axial direction.