JP7226038B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire, and more particularly to a tire having a tread portion divided into four land portions by main grooves.

Patent Document 1 below proposes a tire in which a tread portion is divided into four land portions by three longitudinal main grooves. In the tire of Patent Document 1, each land portion is configured as a rib continuously extending in the tire circumferential direction.

JP 2009-040156 A

In general, when the land portion of the tread portion has high rigidity, the wear resistance tends to be improved, but the initial responsiveness during cornering tends to deteriorate. In particular, when the tread portion is composed of four land portions as in the tire of Patent Document 1, the above tendency is conspicuous because each land portion has a large width in the tire axial direction and high rigidity in the width direction. easy to appear.

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-described problems, and aims to provide a tire having a tread section divided into four land sections and exhibiting excellent wear resistance and initial responsiveness during cornering. Its main purpose.

The present invention provides a tire including a tread portion having a specified direction for mounting on a vehicle, wherein the tread portion includes a first tread end positioned on the outer side of the vehicle when mounted on the vehicle and a second tread end positioned on the inner side of the vehicle when mounted on the vehicle. a tread edge, and extending continuously in the tire circumferential direction between the first tread edge and the second tread edge; and four land portions divided into the main grooves. The main grooves include a first shoulder main groove arranged between the tire equator and the first tread edge, and a second shoulder main groove arranged between the tire equator and the second tread edge. and one crown main groove disposed between the first shoulder main groove and the second shoulder main groove, and the land portion is defined by the first shoulder main groove and the crown main groove. and a second middle land portion between the second shoulder main groove and the crown main groove, the first middle land portion extending on the ground contact surface of the tire equator. is positioned so that the a first deep bottom portion and a second deep bottom portion arranged on both sides in the axial direction of the tire; and a first shallow portion having a smaller depth, the second transverse thin groove includes a second shallow portion and a third shallow portion arranged on both sides in the tire axial direction, and the second shallow portion and the a third deep portion disposed between the third shallow portion and having a greater depth than the second shallow portion and the third shallow portion;

In the tire of the present invention, the second shallow portion is arranged on the first tread end side of the third deep portion, and the length of the second shallow portion in the tire axial direction is equal to the tire length of the third shallow portion. Preferably smaller than the axial length.

In the tire of the present invention, the axial length of the second shallow portion is preferably smaller than the axial length of the first shallow portion.

In the tire of the present invention, the depth of the third shallow portion is preferably smaller than the depth of the first shallow portion.

In the tire of the present invention, it is preferable that the axial length of the third shallow portion is smaller than the axial length of the first shallow portion.

In the tire of the present invention, it is preferable that the first transverse narrow groove and the second transverse narrow groove have a groove width of 3.0 mm or less on the ground contact surface.

In the tire of the present invention, the first transverse narrow groove has a narrow portion having a width of 1.5 mm or less and an opening having a width larger than that of the narrow portion and opening to the tread surface of the first middle land portion. preferably included.

In the tire of the present invention, it is preferable that the width of the second transverse narrow groove is 1.5 mm or less.

In the tire of the present invention, the second middle land portion is provided with a crossing thin groove that crosses the second middle land portion, and the crossing thin groove provided in the second middle land portion extends in the tire axial direction. and a fourth shallow portion and a fifth shallow portion disposed on both sides of the and a depth disposed between the fourth shallow portion and the fifth shallow portion and greater than the fourth shallow portion and the fifth shallow portion and a fourth depth having a depth.

In the tire of the present invention, the fifth shallow portion is arranged on the second tread end side of the fourth deep portion, and the depth of the fifth shallow portion is greater than the depth of the fourth shallow portion. is desirable.

In the tire of the present invention, the first middle land portion is arranged so that the tire equator is positioned on the ground contact surface of the first middle land portion. As a result, a large ground contact pressure acts on the entire contact surface of the first middle land portion, thereby improving the initial responsiveness during turning.

Further, the first middle land portion is provided with a first crossing thin groove and a second crossing thin groove that cross the first middle land portion. As a result, the rigidity of the first middle land portion in the tire circumferential direction is moderately reduced, and the initial responsiveness during cornering is further improved.

Further, the first transverse narrow groove is arranged between a first deep bottom portion and a second deep bottom portion arranged on both sides in the axial direction of the tire, and between the first deep bottom portion and the second deep bottom portion. A first shallow portion and a first shallow portion having a depth less than the second deep portion. The second transverse narrow groove is arranged between a second shallow portion and a third shallow portion arranged on both sides in the axial direction of the tire, and is arranged between the second shallow portion and the third shallow portion. A shallow portion and a third deep portion having a greater depth than the third shallow portion. By defining the depth in this manner, the first transverse fine groove and the second transverse fine groove can exhibit excellent wear resistance and initial responsiveness during turning.

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 a first middle land portion and a second middle land portion in FIG. 1; FIG. 3 is a cross-sectional view taken along line AA of FIG. 2; FIG. 3 is a cross-sectional view taken along line BB of FIG. 2; FIG. 3 is a cross-sectional view taken along line CC of FIG. 2; FIG. 3 is a cross-sectional view taken along line DD of FIG. 2; 3 is a cross-sectional view taken along line EE of FIG. 2; FIG. FIG. 7 is a cross-sectional view taken along line FF of FIG. 6; FIG. 2 is an enlarged view of a first shoulder land portion of FIG. 1; FIG. 10 is a cross-sectional view taken along line GG of FIG. 9; FIG. 2 is an enlarged view of a second shoulder land portion of FIG. 1; FIG. 12 is a cross-sectional view taken along line HH of FIG. 11; FIG. 4 is a developed view of a tread portion of a tire according to another embodiment of the present invention; FIG. 10 is a cross-sectional view of a cross-sectional thin groove of a comparative example;

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. The tire 1 of the present embodiment is suitably used as, for example, a pneumatic tire for passenger cars. However, the present invention is not limited to such an aspect, and may be used for heavy-duty pneumatic tires and non-pneumatic tires in which the interior of the tire is not filled with pressurized air.

As shown in FIG. 1, a tire 1 of the present invention has a tread portion 2 with a specified mounting direction on a vehicle. The tread portion 2 has a first tread end Te1 positioned on the vehicle outer side when the tire 1 is mounted on the vehicle, and a second tread end Te2 positioned on the vehicle inner side when the tire 1 is mounted on the vehicle. The mounting direction to the vehicle is indicated, for example, by characters or symbols on the sidewall portion (not shown).

In the case of a pneumatic tire, the first tread end Te1 and the second tread end Te2 are the outermost ground contact positions in the tire axial direction when the tire 1 in a normal state is applied with a normal load and is grounded on a flat surface with a camber angle of 0°. be. 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 the values measured in the normal condition.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standards on which tires are 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 for ETRTO, it is "LOAD CAPACITY".

The tread portion 2 includes three main grooves 3 continuously extending in the tire circumferential direction between a first tread end Te1 and a second tread end Te2, and four land portions 4 divided into the main grooves 3. It is configured.

The main grooves 3 include first shoulder main grooves 5 arranged between the first tread edge Te1 and the tire equator C, and second shoulder main grooves arranged between the second tread edge Te2 and the tire equator C. 6 and one crown main groove 7 disposed between the first shoulder main groove 5 and the second shoulder main groove 6 .

The axial distance L1 from the tire equator C to the groove centerline of the first shoulder main groove 5 or the second shoulder main groove 6 is preferably 0.15 to 0.35 times the tread width TW. The tread width TW is the axial distance of the tire from the first tread end Te1 to the second tread end Te2 in the normal state.

The crown main groove 7 of the present embodiment is provided on the second tread end Te2 side of the tire equator C, for example. The axial distance L2 from the tire equator C to the groove centerline of the crown main groove 7 is preferably, for example, 0.05 to 0.10 times the tread width TW.

Each main groove 3 of the present embodiment extends linearly parallel to the tire circumferential direction, for example. Each main groove 3 may, for example, extend in a wavy shape.

The groove width W1 of each main groove 3 is preferably, for example, 4.0% to 7.0% of the tread width TW. The depth of each main groove 3 is desirably 5 to 10 mm, for example, in the case of pneumatic tires for passenger cars.

Land portion 4 includes first middle land portion 11 , second middle land portion 12 , first shoulder land portion 13 , and second shoulder land portion 14 . The first middle land portion 11 is divided between the first shoulder main groove 5 and the crown main groove 7 . The second middle land portion 12 is divided between the second shoulder main groove 6 and the crown main groove 7 . The first shoulder land portion 13 is divided between the first shoulder main groove 5 and the first tread edge Te1. The second shoulder land portion 14 is divided between the second shoulder main groove 6 and the second tread edge Te2.

FIG. 2 shows an enlarged view of the first middle land portion 11 and the second middle land portion 12. As shown in FIG. As shown in FIG. 2, the axial width W2 of the first middle land portion 11 and the axial width W3 of the second middle land portion 12 are, for example, 0.10 of the tread width TW. ~0.25 times is desirable. In this embodiment, the width W2 of the first middle land portion 11 and the width W3 of the second middle land portion 12 are substantially the same.

The first middle land portion 11 is arranged so that the tire equator is positioned on its ground contact surface. As a result, a large ground contact pressure acts on the entire ground contact surface of the first middle land portion 11, and the initial responsiveness during turning is improved. In addition, such an arrangement of land portions can suppress uneven wear of the groove edge of the crown main groove 7 and improve wear resistance. In the present embodiment, the tire equator C is arranged closer to the second tread end Te2 than the center position 11c of the first middle land portion 11 in the tire axial direction. The axial distance L3 between the tire equator C and the center position 11c is preferably, for example, 0.20 to 0.40 times the width W2 of the first middle land portion.

A plurality of narrow grooves 15 are provided in each of the first middle land portion 11 and the second middle land portion 12 . As a result, the rigidity of the first middle land portion 11 and the second middle land portion 12 is moderately reduced, and the initial responsiveness during turning is improved. In this specification, the fine groove 15 means a groove having a groove width of 3.0 mm or less at the contact surface of the land portion, and includes a notch called a sipe.

The narrow grooves 15 of this embodiment include a plurality of crossing narrow grooves 16 that cross the land portion 4 and a plurality of non-crossing narrow grooves 17 that extend from the crown main groove 7 and do not cross the land portion 4 . Further, the transverse narrow grooves 16 include transverse narrow grooves 16A arranged in the first middle land portion 11 and transverse narrow grooves 16B arranged in the second middle land portion 12 . The non-crossing narrow grooves 17 include non-crossing narrow grooves 17A arranged in the first middle land portion 11 and non-crossing narrow grooves 17B arranged in the second middle land portion 12 .

The transverse narrow groove 16A provided in the first middle land portion 11 is, for example, inclined in the first direction (downward to the right in FIG. 2) with respect to the axial direction of the tire. The angle of the transverse narrow groove 16A with respect to the axial direction of the tire is, for example, 5 to 10 degrees. Moreover, it is desirable that the crossing thin groove 16A of this embodiment is slightly curved so that the angle with respect to the tire axial direction gradually increases toward the second tread end Te2.

In the present invention, the crossing fine grooves 16A provided in the first middle land portion 11 include first crossing fine grooves 21 and second crossing fine grooves 22 . As a result, the rigidity of the first middle land portion 11 in the tire circumferential direction is moderately reduced, and the initial responsiveness during cornering is further improved. The first crossing narrow grooves 21 and the second crossing narrow grooves 22 are provided alternately in the tire circumferential direction, for example.

FIG. 3 shows a cross-sectional view of the first transverse fine groove 21 of FIG. 2 taken along the line AA. As shown in FIG. 3 , the first transverse narrow groove 21 is arranged in a cross section thereof with a narrow portion 25 having a width W4 of 1.5 mm or less, and a narrow portion 25 radially outward of the narrow portion 25. and an opening 26 opening to the ground contact surface of the land portion with a width greater than that of the portion 25 . The width W5 of the opening 26 of the first crossing thin groove 21 at the contact surface is preferably 1.8 to 2.5 mm, for example. The depth of the opening 26 is, for example, 1.0-2.0 mm. Such first crossing thin grooves 21 make it easier for the contact surface to follow the road surface, which helps to improve the initial responsiveness during steering.

FIG. 4 shows a cross-sectional view of the first transverse fine groove 21 of FIG. 2 taken along the line BB. As shown in FIG. 4, the first crossing thin groove 21 includes, for example, a first deep bottom portion 21a and a second deep bottom portion 21b arranged on both sides in the axial direction of the tire, and a first deep bottom portion 21a and a second deep bottom portion 21b. and a first shallow portion 21c disposed between the bottom portion 21b and having a depth smaller than that of the first deep portion 21a and the second deep portion 21b. That is, the depth of the first crossing thin groove 21 at both ends in the axial direction of the tire is greater than the depth of the central portion in the axial direction of the tire.

FIG. 5 shows a CC line cross-sectional view of the second transverse fine groove 22 of FIG. As shown in FIG. 5, the second crossing narrow groove 22 includes a second shallow portion 22a and a third shallow portion 22b arranged on both sides in the axial direction of the tire, and a second shallow portion 22a and a third shallow portion 22b. and a third deep portion 22c having a greater depth than the second shallow portion 22a and the third shallow portion 22b. The third deep bottom portion 22c is arranged at a position including the central portion of the second crossing narrow groove 22 in the tire axial direction. In this embodiment, the second shallow portion 22a is arranged on the first tread end Te1 side of the third deep portion 22c. The third shallow portion 22b is arranged on the second tread end Te2 side of the third deep portion 22c.

By defining the depth in this way, the ground contact surface of the first middle land portion 11 can easily follow the road surface when steering is started, while the shallow bottom portions prevent the transverse narrow grooves from opening excessively. , the edge of each transverse slot provides a large frictional force. This action enhances the initial responsiveness during turning. In addition, each shallow portion maintains the rigidity of the first middle land portion 11, improving wear resistance. Therefore, the first crossing fine groove 21 and the second crossing fine groove 22 of the present invention can exhibit excellent wear resistance and initial response during turning.

As shown in FIG. 4, the maximum depth d3 of the crossing thin groove 16 (corresponds to the depth of the first deep bottom portion 21a or the second deep bottom portion 21b of the first crossing thin groove 21 in this embodiment). is, for example, 0.60 to 1.00 times the depth d1 of the crown main groove 7, and more preferably 0.65 to 0.75 times. The depth d2 of the first shallow bottom portion 21c is preferably 0.30 to 0.50 times the depth d1 of the crown main groove 7, for example.

The axial length L4 of the first shallow bottom portion 21c is, for example, 0.25 to 0.25 of the axial width W2 of the first middle land portion 11 (shown in FIG. 2 and the same applies hereinafter). .50 times. The axial length L4 of the first shallow portion 21c is preferably larger than the axial length of the first deep portion 21a and the axial length of the second deep portion 21b. Such a first shallow portion 21c enhances wear resistance and initial responsiveness during turning in a well-balanced manner.

As shown in FIG. 2, the second transverse fine groove 22 extends, for example, along the first transverse fine groove 21 and, in a preferred embodiment, parallel to the first transverse fine groove 21 .

It is desirable that the width of the second transverse narrow groove 22 is, for example, 1.5 mm or less, and in this embodiment, the width is 0.5 to 1.0 mm.

As shown in FIG. 5, the depth d4 of the third deep bottom portion 22c of the second transverse narrow groove 22 is preferably 0.60 to 1.00 times the depth d1 of the crown main groove 7, for example. . In this embodiment, the depth d4 of the third deep bottom portion 22c is the same as the depths of the first deep bottom portion 21a and the second deep bottom portion 21b (shown in FIG. 4).

The depth d5 of the second shallow portion 22a is 0.15 to 0.50 times the depth d1 of the crown main groove 7, for example. In a more desirable aspect, the depth d5 of the second shallow portion 22a is 0.40 to 0.85 times the depth d4 of the third deep portion 22c. The depth d6 of the third shallow portion 22b is preferably smaller than that of the second shallow portion 22a. In this embodiment, the depth d6 of the third shallow portion 22b is the same as the depth of the opening 26 (shown in FIG. 3) of the first crossing thin groove 21. As shown in FIG. Such second crossing narrow grooves 22 maintain the rigidity of the first middle land portion 11 on the side of the tire equator C, and improve steering stability and wear resistance.

The axial length L5 of the third deep bottom portion 22c is, for example, 0.45 to 0.65 times the axial width W2 of the first middle land portion 11 . It is desirable that the axial length L5 of the third deep bottom portion 22c of the present embodiment is longer than the axial length L4 of the first shallow bottom portion 21c of the first crossing thin groove 21, for example.

The axial length L6 of the second shallow portion 22a is the axial length L5 of the third deep portion 22c, the axial length L7 of the third shallow portion 22b, and the first transverse narrow groove. 21 is smaller than the axial length L4 of the first shallow bottom portion 21c. Specifically, the length L6 of the second shallow portion 22a is 0.05 to 0.20 times the width W2 of the first middle land portion 11 in the tire axial direction. Such a second shallow portion 22a makes it easier to open the first tread edge Te1 side of the second crossing narrow groove 22, and can improve wet performance.

The axial length L7 of the third shallow portion 22b is, for example, smaller than the axial length L5 of the third deep portion 22c. less than L4. The length L7 of the third shallow portion 22b is 0.30 to 0.40 times the width W2 of the first middle land portion 11, for example.

As shown in FIG. 2, each of the non-crossing narrow grooves 17 preferably communicates with the crossing narrow grooves 16 adjacent in the tire circumferential direction. Each of the non-crossing narrow grooves 17A provided in the first middle land portion 11 communicates with the adjacent first crossing narrow groove 21 in the circumferential direction of the first tire (upward in FIG. 2). Also, in the first middle land portion 11 , the non-crossing thin groove 17A is provided between the first crossing thin groove 21 and the second crossing thin groove 22 .

It is desirable that the non-transverse narrow groove 17 has a width of, for example, 1.5 mm or less, and in this embodiment, it has a width of 0.5 to 1.0 mm.

The non-crossing narrow groove 17</b>A includes a first portion 31 inclined in the first direction with respect to the tire axial direction and a second portion 32 bending from the first portion 31 and extending to the crossing narrow groove 16 . The first portion 31 preferably extends along the transverse groove 16, for example. The second portion 32 is curved in an arc shape from the first portion 31 and communicates with the transverse narrow groove 16 . The non-crossing thin groove 17 crosses the axial center position 11c of the first middle land portion 11, and the second portion 32 is located closer to the first tread edge Te1 than the center position 11c. It communicates with 1 crossing fine groove 21 . Such non-transverse fine grooves 17 improve wet performance while maintaining steering stability and wear resistance. However, the non-crossing narrow groove 17A is not limited to such a mode.

FIG. 6 shows a cross-sectional view of the first portion 31 of FIG. 2 taken along line DD. As shown in FIG. 6, the maximum depth d8 of the non-crossing narrow grooves 17 (corresponding to the maximum depth of the first portion 31 in this embodiment) is equal to the maximum depth d3 of the crossing narrow grooves 16. (shown in FIG. 4) is 0.40 to 1.50 times, more preferably 0.90 to 1.10 times. Moreover, it is desirable that the first portion 31 has, for example, a shallow bottom portion 31a in which the end portion on the crown main groove 7 side protrudes. The shallow portion 31a of the first portion 31 has, for example, substantially the same shape as the second shallow portion 22a of the second crossing thin groove 22, and the configuration of the second shallow portion 22a described above is the same as the shallow portion 31a of the first portion 31. It can be applied to the bottom portion 31a.

The maximum depth of the second portion 32 is smaller than the maximum depth of the first portion 31, for example. It is desirable that the maximum depth of the second portion 32 is smaller than the depth of the shallow portion 31a of the first portion 31 . In this embodiment, the depth of the second portion 32 is the same as the depth of the opening 26 of the first transverse narrow groove 21 .

As shown in FIG. 2, the crossing narrow grooves 16B and the non-crossing narrow grooves 17B provided in the second middle land portion 12 are inclined in the first direction with respect to the axial direction of the tire, for example. The transverse narrow grooves 16B provided in the second middle land portion 12 are inclined at a larger angle with respect to the tire axial direction than the transverse narrow grooves 16A provided in the first middle land portion 11 . The angle of the transverse narrow groove 16B provided in the second middle land portion 12 with respect to the tire axial direction is, for example, 20 to 30°. Moreover, it is desirable that the crossing narrow groove 16B of this embodiment is slightly curved so that the angle with respect to the tire axial direction gradually increases toward the second tread end Te2.

The crossing fine grooves 16B provided in the second middle land portion 12 include third crossing fine grooves 23 and fourth crossing fine grooves 24 . At least a part of the cross section of the third transverse narrow groove 23 has the same cross-sectional shape as the first transverse narrow groove 21 shown in FIG. and an opening 26 opening to the ground contact surface of the land portion with a width larger than that of the narrow portion. As with the second transverse narrow grooves 22, the fourth transverse narrow grooves 24 are preferably configured with a width of 1.5 mm or less as a whole, and in this embodiment, the width of the whole is 0.5 to 1.0 mm. width.

FIG. 7 shows a cross-sectional view of the third transverse fine groove 23 of FIG. 2 taken along line EE. As shown in FIG. 7, the third transverse narrow groove 23 includes, for example, a first groove portion 23a communicating with the crown main groove 7, a second groove portion 23b communicating with the second shoulder main groove 6, and a first groove portion 23a. and a third groove portion 23c between the second groove portion 23b. The first groove portion 23 a and the second groove portion 23 b include the narrow portion 25 and the opening portion 26 . Further, the third groove portion 23c has a depth smaller than that of the first groove portion 23a and the second groove portion 23b, and is composed only of the opening portion 26 in this embodiment. Such third crossing narrow grooves 23 help to maintain the rigidity of the second middle land portion 12 and exhibit excellent steering stability and wear resistance.

The third groove portion 23c crosses, for example, the central position of the second middle land portion 12 in the tire axial direction. Further, the axial length L8 of the third groove portion 23c is, for example, 0.35 to 0.35 of the axial width W3 of the second middle land portion 12 (shown in FIG. 2, the same shall apply hereinafter). 0.50 times is desirable.

FIG. 8 shows a cross-sectional view of the fourth transverse fine groove 24 of FIG. 2 taken along line FF. As shown in FIG. 8, the fourth crossing thin groove 24 has a raised bottom surface at least in a region including the end portion on the crown main groove 7 side. The fourth crossing thin groove 24 of this embodiment includes, for example, a fourth shallow portion 24a and a fifth shallow portion 24b arranged on both sides in the tire axial direction, and the fourth shallow portion 24a and the fifth shallow portion 24b. and a fourth deep portion 24c disposed therebetween and having a greater depth than the fourth shallow portion 24a and the fifth shallow portion 24b. The fourth shallow portion 24a is provided on the first tread end Te1 side of the fourth deep portion 24c, and the fifth shallow portion 24b is provided on the second tread end Te2 side of the fourth deep portion 24c.

The fourth shallow portion 24a has, for example, the same depth as the opening 26 described above. The axial length L9 of the fourth shallow bottom portion 24a is preferably greater than the axial length L8 (shown in FIG. 7) of the third groove portion 23c of the third transverse thin groove 23. As shown in FIG. The length L9 of the fourth shallow bottom portion 24a is 0.40 to 0.55 times the width W3 of the second middle land portion 12 in the tire axial direction. Such a fourth shallow bottom portion 24a helps maintain the rigidity of the second middle land portion 12 on the tire equator C side.

It is desirable that the depth of the fifth shallow portion 24b is, for example, greater than the depth of the fourth shallow portion 24a. The fifth shallow portion 24b has, for example, substantially the same shape as the second shallow portion 22a of the second transverse narrow groove 22 shown in FIG. can be done.

The depth d7 of the fourth deep bottom portion 24c is 0.60 to 1.00 times the depth d1 of the crown main groove 7, for example. The fourth deep bottom portion 24c crosses, for example, the center position of the second middle land portion 12 in the tire axial direction. The axial length L10 of the fourth deep bottom portion 24c is greater than, for example, the axial length of the first groove portion 23a or the second groove portion 23b of the third transverse thin groove 23 . Specifically, the length L10 of the fourth deep bottom portion 24c is 0.30 to 0.50 times the width W3 of the second middle land portion 12 in the tire axial direction.

As shown in FIG. 2, the non-crossing narrow groove 17B provided in the second middle land portion 12 communicates with the crossing narrow groove 16B adjacent in the tire circumferential direction. The non-crossing narrow groove 17B preferably communicates with the adjacent crossing narrow groove 16B in a second tire circumferential direction opposite to the first tire circumferential direction (downward in FIG. 2), for example. Each of the non-crossing narrow grooves 17B of this embodiment communicates with the third crossing narrow groove 23 . Arrangement of such non-crossing narrow grooves 17 helps to suppress uneven wear of each land portion.

The non-crossing narrow groove 17B provided in the second middle land portion 12 has substantially the same structure as the non-crossing narrow groove 17A provided in the first middle land portion 11 except for the above-described structure. Therefore, the configuration of the non-crossing narrow groove 17A described above can be applied to the non-crossing narrow groove 17B provided in the second middle land portion 12 .

The non-crossing narrow groove 17A provided in the first middle land portion 11 is smoothly connected to any one of the crossing narrow grooves 16B provided in the second middle land portion 12 via the crown main groove 7 . The non-crossing narrow groove 17B provided in the second middle land portion 12 is smoothly connected to any one of the crossing narrow grooves 16A provided in the first middle land portion 11 via the crown main groove 7 . The arrangement of such fine grooves helps improve wet performance and ride comfort. It should be noted that two fine grooves 15 are smoothly continuous through the crown main groove 7 means that one fine groove is extended in its longitudinal direction as a first imaginary groove portion and the other fine groove is extended in its lengthwise direction. It includes an aspect in which the distance in the tire circumferential direction from the second imaginary groove portion extending in the longitudinal direction is 2 mm or less in the crown main groove 7 . In a more desirable aspect, the first virtual groove portion and the second virtual groove portion overlap within the crown main groove 7 .

Specifically, it is desirable that the non-crossing narrow grooves 17A provided in the first middle land portion 11 are smoothly continuous with the fourth crossing narrow grooves 24 via the crown main grooves 7 . It is desirable that the non-crossing narrow grooves 17B provided in the second middle land portion 12 are smoothly continuous with the second crossing narrow grooves 22 via the crown main grooves 7 . As a more desirable aspect, in this embodiment, the first crossing fine groove 21 is smoothly continuous with the third crossing fine groove 23 via the crown main groove 7 .

In the first middle land portion 11, the total number N1 of crossing narrow grooves 16A is greater than the total number N2 of non-crossing narrow grooves 17A. Also in the second middle land portion 12, the total number N1 of crossing thin grooves 16B is greater than the total number N2 of non-crossing thin grooves 17B. The total number N1 is, for example, 1.5 to 2.5 times the total number N2. Such arrangement of the fine grooves can ensure wet performance while exhibiting the above-described effects.

In the first middle land portion 11 and the second middle land portion 12 of the present embodiment, only the narrow grooves 15 having a groove width of 3.0 mm or less are provided, and the groove width is larger than 3.0 mm. is not provided. Such groove arrangement provides excellent steering stability and wear resistance.

FIG. 9 shows an enlarged view of the first shoulder land portion 13. As shown in FIG. As shown in FIG. 9 , the first shoulder land portion 13 has the largest width of the ground contact surface in the axial direction of the four land portions. The axial width W6 of the first shoulder land portion 13 is preferably, for example, 0.25 to 0.35 times the tread width TW. Such a first shoulder land portion 13 can provide a linear steering response during turning, and can improve steering stability.

The first shoulder land portion 13 has a plurality of first shoulder lateral grooves 35 with a groove width greater than 3.0 mm on the ground contact surface and a plurality of first shoulder lateral grooves 35 with a groove width of 3.0 mm or less on the ground contact surface. A shoulder narrow groove 36 is provided.

The first shoulder lateral groove 35 , for example, extends from the first tread edge Te<b>1 and discontinues within the first shoulder land portion 13 . The first shoulder lateral groove 35 crosses, for example, the center position of the first shoulder land portion 13 in the tire axial direction. The axial length L11 of the first shoulder lateral groove 35 is, for example, 0.75 to 0.90 times the axial width W6 of the first shoulder land portion 13 . Such first shoulder lateral grooves 35 serve to improve steering stability and riding comfort in a well-balanced manner.

The first shoulder thin groove 36, for example, preferably has a width of 1.5 mm or less as a whole, and in this embodiment, has a width of 0.5 to 1.0 mm. The first shoulder narrow groove 36 , for example, extends from the first shoulder main groove 5 and discontinues within the first shoulder land portion 13 . The first shoulder narrow groove 36 is interrupted, for example, on the first shoulder main groove 5 side of the center position of the first shoulder land portion 13 in the tire axial direction. Further, the first shoulder thin groove 36 is discontinued on the first tread end Te1 side of the axially inner inner end of the first shoulder lateral groove 35 . The axial length L12 of the first shoulder narrow groove 36 is, for example, 0.35 to 0.45 times the axial width W6 of the first shoulder land portion 13 .

FIG. 10 shows a cross-sectional view of the first shoulder narrow groove 36 of FIG. 9 taken along line GG. As shown in FIG. 10, the first shoulder narrow groove 36 preferably includes a shallow portion 36a having a raised bottom surface in a region including the axially inner end portion of the tire. Such first shoulder thin grooves 36 do not open excessively when the vehicle touches the ground, thereby improving steering stability and wear resistance.

As shown in FIG. 9, each of the first shoulder lateral grooves 35 and the first shoulder narrow grooves 36 is preferably inclined in the second direction opposite to the first direction with respect to the axial direction of the tire. . Moreover, it is desirable that each of the first shoulder lateral grooves 35 and the first shoulder thin grooves 36 has an angle of 5 to 20 degrees with respect to the tire axial direction.

FIG. 11 shows an enlarged view of the second shoulder land portion 14. As shown in FIG. As shown in FIG. 11 , the second shoulder land portion 14 has the smallest axial width of the contact surface of the four land portions. The axial width W7 of the second shoulder land portion 14 is 0.10 times or more the tread width TW, preferably 0.12 to 0.25 times the tread width TW. Such a second shoulder land portion 14 can further improve ride comfort.

The second shoulder land portion 14 has a plurality of second shoulder lateral grooves 37 with a groove width of more than 3.0 mm on the ground contact surface, and a plurality of second shoulder lateral grooves 37 with a groove width of 3.0 mm or less on the ground contact surface. A shoulder narrow groove 38 is provided.

The second shoulder lateral groove 37 , for example, extends from the second tread edge Te<b>2 and discontinues within the second shoulder land portion 14 . The axial length L13 of the second shoulder lateral groove 37 is, for example, 0.50 times or more the axial width W7 of the second shoulder land portion 14, and more preferably 0.60 to 0.60 times the tread width TW. 0.80 times. Such second shoulder lateral grooves 37 can improve ride comfort and wet performance while maintaining steering stability.

The second shoulder lateral groove 37 includes a tapered portion 37a whose groove width gradually decreases toward an axially inner inner end 37i. The tapered portion 37a tapers in depth towards the inner end 37i. Such a second shoulder lateral groove 37 can suppress uneven wear at the tapered portion 37a.

The second shoulder thin groove 38 has, for example, a narrow portion 25 with a width of 1.5 mm or less and a land portion with a width larger than the narrow portion 25, similar to the cross-sectional shape of the first transverse thin groove 21 shown in FIG. and an opening 26 that opens to the ground plane of the part. The axial length of the second shoulder narrow grooves 38 is preferably greater than the axial length of the second shoulder lateral grooves 37 . The second shoulder narrow grooves 38 of the present embodiment, for example, extend from the second shoulder main grooves 6 to the second tread edge Te2.

FIG. 12 shows a cross-sectional view of the second shoulder narrow groove 38 of FIG. 11 taken along the line HH. As shown in FIG. 12, the second shoulder narrow groove 38 preferably includes a shallow portion 38a having a raised bottom surface in a region including the axially inner end portion of the tire. Such second shoulder narrow grooves 38 serve to improve steering stability and riding comfort in a well-balanced manner.

As shown in FIG. 11, each of the second shoulder lateral grooves 37 and the second shoulder thin grooves 38 is preferably inclined in the second direction with respect to the tire axial direction. Moreover, it is desirable that each of the second shoulder lateral grooves 37 and the second shoulder thin grooves 38 has an angle of 5 to 20 degrees with respect to the tire axial direction.

FIG. 13 shows a developed view of the tread portion 2 of the tire 1 of another embodiment of the invention. In FIG. 13, elements common to those described above are denoted by the same reference numerals, and descriptions thereof are omitted here.

In this embodiment, portions corresponding to the openings 26 shown in FIG. 3 are removed from each of the transverse narrow grooves 16 and non-crossing narrow grooves 17 of the embodiment shown in FIG. Such an embodiment can further enhance steering stability compared to the embodiment shown in FIG.

Although the tire of one 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 tire of size 235/50R18 having the basic pattern of FIG. 1 was prototyped. As a comparative example, a tire having the basic pattern shown in FIG. 1 and each transverse narrow groove having a cross section shown in FIG. 14 was produced. As shown in FIG. 14, each transverse narrow groove a of the tire of the comparative example has a flat bottom surface. The tire of the comparative example has the same configuration as the tire shown in FIG. 1 except for the configuration described above. Each test tire was tested for wear resistance and initial response during cornering. Common specifications and test methods for each test tire are as follows.
Mounting rim: 18 x 7.5J
Tire internal pressure: front wheel 240kPa, rear wheel 240kPa
Test vehicle: 3000cc displacement, 4WD vehicle Tire mounting position: All wheels

<Abrasion resistance>
The wear amount of the first middle land portion was measured when the test vehicle was driven on a dry road surface for a certain distance. The results are indexed with the wear amount of the comparative example being 100, and the smaller the number, the better the wear resistance.

<Initial responsiveness during turning>
When the test vehicle was run on a dry road surface, the initial responsiveness during cornering 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 initial response during turning.
The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that the tires of Examples exhibited excellent wear resistance and initial response during cornering.

2 tread portion 3 main groove 4 land portion 5 first shoulder main groove 6 second shoulder main groove 7 crown main groove 11 first middle land portion 12 second middle land portion 21 first transverse narrow groove 22 second transverse narrow groove 21a First deep portion 21b Second deep portion 21c First shallow portion 22a Second shallow portion 22b Third shallow portion 22c Third deep portion Te1 First tread end Te2 Second tread end

Claims (10)

A tire including a tread portion with a specified orientation for mounting on a vehicle,
The tread portion is
including a first tread end positioned on the vehicle outer side when mounted on the vehicle and a second tread end positioned on the vehicle inner side when mounted on the vehicle; and
Consists of three main grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and four land portions divided into the main grooves,
The main grooves include first shoulder main grooves arranged between the tire equator and the first tread edge, second shoulder main grooves arranged between the tire equator and the second tread edge, and Consists of one crown main groove arranged between the first shoulder main groove and the second shoulder main groove,
The land portion includes a first middle land portion between the first shoulder main groove and the crown main groove, and a second middle land portion between the second shoulder main groove and the crown main groove. ,
The first middle land portion is arranged so that the tire equator is positioned on the ground contact surface thereof,
The first middle land portion is provided with a first crossing thin groove and a second crossing thin groove that cross the first middle land portion,
The first transverse narrow groove is arranged between a first deep bottom portion and a second deep bottom portion arranged on both sides in the axial direction of the tire, and between the first deep bottom portion and the second deep bottom portion and the first deep bottom portion. a deep portion and a first shallow portion having a depth smaller than the second deep portion;
The second transverse thin groove is arranged between a second shallow portion and a third shallow portion arranged on both sides in the axial direction of the tire, and is arranged between the second shallow portion and the third shallow portion. a shallow portion and a third deep portion having a greater depth than the third shallow portion;
tire. The second shallow portion is arranged on the first tread end side of the third deep portion,
The tire according to claim 1, wherein the axial length of the second shallow portion is smaller than the axial length of the third shallow portion. The tire according to claim 1 or 2, wherein the axial length of the second shallow portion is smaller than the axial length of the first shallow portion. The tire according to any one of claims 1 to 3, wherein the depth of the third shallow portion is smaller than the depth of the first shallow portion. The tire according to any one of claims 1 to 4, wherein the axial length of the third shallow portion is smaller than the axial length of the first shallow portion. The tire according to any one of claims 1 to 5, wherein each of said first transverse narrow groove and said second transverse narrow groove has a groove width of 3.0 mm or less on said contact surface. 2. The first transverse narrow groove includes a narrow portion having a width of 1.5 mm or less and an opening having a width larger than that of the narrow portion and opening to the tread surface of the first middle land portion. 7. The tire according to any one of 6. 8. The tire according to any one of claims 1 to 7, wherein said second transverse narrow groove is constructed with a width of 1.5 mm or less as a whole. the second middle land portion is provided with a transverse narrow groove that crosses the second middle land portion;
The transverse narrow groove provided in the second middle land portion is located between a fourth shallow portion and a fifth shallow portion disposed on both sides in the tire axial direction, and between the fourth shallow portion and the fifth shallow portion. 9. A tire according to any one of claims 1 to 8, comprising a fourth deep portion disposed in the rim and having a greater depth than said fourth shallow portion and said fifth shallow portion. The fifth shallow portion is arranged on the second tread end side of the fourth deep portion,
10. The tire of claim 9, wherein the depth of the fifth shallow portion is greater than the depth of the fourth shallow portion.

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