JP7275782B2 - 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 three land portions by main grooves.

Conventionally, various tires have been proposed in which a tread portion is divided into three land portions by main grooves. For example, the tread portion of the pneumatic tire disclosed in Patent Document 1 includes a center land portion divided between a pair of center main grooves and a pair of shoulder land portions provided axially outside the center land portion. is provided.

JP 2015-024797 A

In general, a tire in which a tread portion is divided into three land portions by a main groove tends to have a large axial width of each land portion. Therefore, in the tire, each land portion has a high rigidity, which tends to impair ride comfort. On the other hand, it is conceivable to provide grooves in the land portions as a method of reducing the rigidity of the land portions to improve ride comfort. However, the grooves provided in the land tend to impair the noise performance because they generate various noises when grounded.

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation as described above. is the main purpose.

The present invention provides a tire including a tread portion, the tread portion including a first tread edge and a second tread edge, and a tire circumferential direction between the first tread edge and the second tread edge. and three land portions divided into the main grooves, the main grooves being arranged between the tire equator and the first tread edge. A main groove and a second main groove disposed between the tire equator and the second tread edge, and the land portion is a crown land between the first main groove and the second main groove. wherein the crown land portion is provided with a plurality of crossing thin grooves that cross the crown land portion and a plurality of non-crossing thin grooves that extend from one of the main grooves and do not cross the crown land portion. It is

In the tire of the present invention, it is preferable that the transverse narrow grooves and the non-crossing narrow grooves have a groove width of 3.0 mm or less at the contact surface of the crown land portion.

In the tire of the present invention, the transverse narrow groove comprises a narrow portion having a width of 1.5 mm or less in a cross section orthogonal to the longitudinal direction, and a narrow portion extending outward from the narrow portion in the tire radial direction. and an opening opening into the ground contact surface of said crown land portion with a width greater than.

In the tire of the present invention, the transverse narrow groove is arranged between a first shallow portion and a second shallow portion arranged on both sides in the tire axial direction, and between the first shallow portion and the second shallow portion. and a deep portion having a depth greater than that of the first shallow portion and the second shallow portion.

In the tire of the present invention, the non-crossing narrow groove includes a first portion extending along the crossing narrow groove from the main groove and a second portion bending from the first portion and extending to the crossing narrow groove. is desirable.

In the tire of the present invention, the first portion comprises a narrow portion having a width of 1.5 mm or less in a cross section orthogonal to the longitudinal direction, and a narrow portion extending outward from the narrow portion in the tire radial direction. and an opening opening into the ground contact surface of said crown land portion with a width greater than.

In the tire of the present invention, it is preferable that the first portion includes a shallow portion having a raised groove bottom at an end communicating with the main groove.

In the tire of the present invention, the non-crossing narrow grooves include first non-crossing narrow grooves extending from the first main grooves to the crossing narrow grooves and second non-crossing narrow grooves extending from the second main grooves to the crossing narrow grooves. It preferably includes a groove.

In the tire of the present invention, it is preferable that the crown land portion is not provided with a groove having a groove width exceeding 3.0 mm at the ground contact surface.

Generally, in a tire in which the tread portion is divided into three land portions by a main groove, a large ground contact pressure acts on the crown land portion. Therefore, the configuration of the crown land portion tends to greatly affect ride comfort and noise performance. Based on this mechanism, the crown land portion of the tire of the present invention includes a plurality of transverse thin grooves that cross the crown land portion and a plurality of grooves that extend from one main groove and do not cross the crown land portion. Non-transverse slots are provided. Each narrow groove reduces the amount of air that passes when grounded, and can suppress the pumping noise.

In addition, the crossing narrow groove cooperates with the non-crossing narrow groove to sufficiently reduce the rigidity of the crown land portion, thereby improving ride comfort. On the other hand, the non-crossing narrow grooves do not cross the crown land portion, and the amount of air flowing in and out of the interior thereof at the time of ground contact is small, so that the pumping noise is small. Therefore, the tire of the present invention can prevent significant deterioration in noise performance.

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 crown land portion of 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; FIG. 2 is an enlarged view of a first shoulder land portion of FIG. 1; FIG. 8 is a cross-sectional view taken along line EE of FIG. 7; FIG. 2 is an enlarged view of a second shoulder land portion of FIG. 1; FIG. 10 is a cross-sectional view taken along line FF of FIG. 9; FIG. 4 is a developed view of a tread portion of a tire according to another embodiment of the present invention; It is an enlarged view of the crown land part 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, the tire 1 of the present embodiment has a specified mounting direction to the vehicle. However, the tire of the present invention is not limited to such an aspect. 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 by letters or symbols on the side wall portion (not shown), for example.

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 loaded with a normal load and grounds 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 standards on which tires are based. AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is "LOAD CAPACITY".

The tread portion 2 includes two main grooves 3 continuously extending in the tire circumferential direction between a first tread end Te1 and a second tread end Te2, and three land portions 4 divided by the main grooves 3. It consists of

The main groove 3 extends 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. The main groove 3 has a groove width at least greater than 3.0 mm. In a preferred embodiment, each main groove 3 has a groove width and depth of 5 mm or more, more preferably 6 mm or more. Further, the groove width W1 of the main groove 3 is, for example, 5.0% to 8.0% of the tread width TW. The depth of the main groove 3 is, for example, 5-12 mm. Each main groove 3 of the present embodiment extends linearly along the tire circumferential direction, for example. Alternatively, each main groove 3 may be non-linear, such as zigzag or wavy. 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 main grooves 3 include a first main groove 5 arranged between the tire equator C and the first tread edge Te1, and a second main groove 6 arranged between the tire equator C and the second tread edge Te2. consists of

A tire axial distance L1 from the tire equator C to the groove center line of the first main groove 5 and a tire axial distance L2 from the tire equator C to the groove center line of the second main groove 6 are, for example, the tread Desirably, it is 0.08 to 0.25 times the width TW. Moreover, in this embodiment, the distance L1 is smaller than the distance L2.

The land portion 4 is composed of a crown land portion 10 , a first shoulder land portion 11 and a second shoulder land portion 12 . The crown land portion 10 is divided between the first main groove 5 and the second main groove 6 . The first shoulder land portion 11 is divided between the first main groove 5 and the first tread edge Te1. The second shoulder land portion 12 is divided between the second main groove 6 and the second tread edge Te2.

An enlarged view of the crown land portion 10 is shown in FIG. As shown in FIG. 2, the width W2 of the crown land portion 10 is preferably, for example, 0.20 to 0.30 times the tread width TW (shown in FIG. 1 and the same applies hereinafter). . Further, the center position 10c of the crown land portion 10 in the tire axial direction is located on the second main groove 6 side of the tire equator C. As shown in FIG. The axial distance L3 between the tire equator C and the axial center position 10c of the crown land portion 10 is preferably 0.15 to 0.30 times the width W2 of the crown land portion 10. As shown in FIG.

A plurality of fine grooves 15 are provided in the crown land portion 10 . The narrow 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 so-called sipes. In the crown land portion 10 of the present embodiment, no groove having a groove width exceeding 3.0 mm at the ground contact surface is arranged.

The narrow grooves 15 include crossing narrow grooves 16 that cross the crown land portion 10 and a plurality of non-crossing narrow grooves 17 that extend from one main groove and do not cross the crown land portion. The crown land portion 10 of the present invention is provided with a plurality of crossing narrow grooves 16 and a plurality of non-crossing narrow grooves 17 . The transverse narrow grooves 16 and the non-crossing narrow grooves 17 have a groove width of 3.0 mm or less at the contact surface of the crown land portion 10 . Each narrow groove reduces the amount of air that passes when grounded, and can suppress the pumping noise.

In addition, the crossing narrow grooves 16 cooperate with the non-crossing narrow grooves 17 to sufficiently reduce the rigidity of the crown land portion 10, thereby improving ride comfort. On the other hand, the non-crossing narrow grooves 17 do not cross the crown land portion 10, and the amount of air flowing in and out of the interior of the non-crossing narrow grooves 17 at the time of ground contact is small, so the pumping noise is small. Therefore, the tire of the present invention can prevent significant deterioration in noise performance.

The transverse narrow groove 16 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 16 with respect to the axial direction of the tire is, for example, 10 to 30 degrees. Moreover, it is desirable that the crossing narrow groove 16 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.

FIG. 3 shows a cross-sectional view of the transverse narrow groove 16 of FIG. 2 taken along the line AA. As shown in FIG. 3, the transverse narrow groove 16 is continuous with the narrow portion 25 having a width W3 of 1.5 mm or less and the narrow portion 25 on the outer side in the tire radial direction in a cross section orthogonal to the longitudinal direction. and an opening 26 that opens to the ground contact surface of the land portion with a width greater than that of the narrow portion 25 . The width W4 of the opening 26 of the transverse narrow groove 16 at the contact surface is desirably 1.8 to 2.5 mm, for example. The depth of the opening 26 is, for example, 1.0-2.0 mm. Such transverse narrow grooves 16 further improve riding comfort.

FIG. 4 shows a cross-sectional view of the transverse narrow groove 16 of FIG. 2 taken along the line BB. As shown in FIG. 4, the transverse thin groove 16 is formed by a first shallow portion 16a and a second shallow portion 16b arranged on both sides in the axial direction of the tire, and the first shallow portion 16a and the second shallow portion 16b. and a deep portion 16c disposed therebetween and having a greater depth than the first shallow portion 16a and the second shallow portion 16b. Such transverse grooves 16 produce less pumping noise and help reduce noise performance degradation.

In the present embodiment, the deep bottom portion 16c is arranged at a position including the central portion of the crossing narrow groove 16 in the tire axial direction. The first shallow portion 16a is arranged on the first tread end Te1 side of the deep portion 16c. The second shallow portion 16b is arranged on the second tread end Te2 side of the deep portion 16c. However, the tire of the present invention is not limited to such an aspect.

The depth d2 of the deep bottom portion 16c is preferably 0.60 to 1.00 times the depth d1 of the main groove 3, for example. In this embodiment, the depth d2 of the deep bottom portion 16c is 0.65 to 0.85 times the depth d1 of the main groove 3.

The depth d3 of the first shallow portion 16a and the second shallow portion 16b is 0.30 to 0.50 times the depth d1 of the main groove 3, for example. In a more desirable mode, the depth d3 of the first shallow portion 16a and the second shallow portion 16b is 0.50 to 0.70 times the depth d2 of the deep portion 16c. In this embodiment, the first shallow portion 16a and the second shallow portion 16b have the same depth. Such transverse narrow grooves 16 can enhance ride comfort and noise performance in a well-balanced manner.

The length L4 of the deep bottom portion 22c in the axial direction of the tire is, for example, 0.45 to 0.65 times the width W2 of the crown land portion 10 in the axial direction of the tire (shown in FIG. 2 and the same shall apply hereinafter). be.

The axial length L5 of the first shallow portion 16a and the axial length L6 of the second shallow portion 16b are smaller than the axial length L4 of the deep portion 16c. Specifically, the length L5 and the length L6 are 0.05 to 0.20 times the width W2 of the crown land portion 10, respectively.

As shown in FIG. 2, each of the non-crossing narrow grooves 17 provided in the crown land portion 10 preferably communicates with the crossing narrow grooves 16 adjacent in the tire circumferential direction.

The non-crossing narrow groove 17 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 thin groove 16 . In the non-crossing narrow groove 17, the first portion 31 crosses the center position 10c of the crown land portion 10 in the axial direction of the tire. Such non-crossing thin grooves 17 serve to reduce the rigidity of the crown land portion 10 and further improve ride comfort.

FIG. 5 shows a CC line cross-sectional view of the first portion 31 of FIG. As shown in FIG. 5, the first portion 31 is connected to a narrow portion 33 having a width W7 of 1.5 mm or less on a cross section orthogonal to the longitudinal direction, and extending outward from the narrow portion 33 in the tire radial direction. and an opening 34 that opens to the ground contact surface of the crown land portion 10 with a width larger than that of the narrow portion 33 .

In the first portion 31 of the present embodiment, one groove wall extends in parallel along the tire radial direction, and the other groove wall is bent at the opening 34 in a direction to increase the groove width. The non-transverse fine grooves 17 including the first portion 31 as described above, along with the above-described transverse fine grooves 16, can turn the pumping sound into white noise, which in turn helps improve noise performance.

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 d4 of the non-crossing narrow grooves 17 (corresponding to the maximum depth of the first portion 31 in this embodiment) is the maximum depth d2 of the crossing narrow grooves 16. (shown in FIG. 4). Moreover, it is desirable that the first portion 31 has a shallow portion 31a having a raised groove bottom at the end on the main groove 3 side, for example. The shallow portion 31a of the first portion 31 has, for example, substantially the same shape as the shallow portion of the transverse narrow groove 16, and the configuration of the shallow portion described above can be applied to the shallow portion 31a of the first portion 31. .

The depth d5 of the shallow portion 31a of the first portion 31 is preferably 0.30 to 0.50 times the depth d1 of the main groove 3. Such a first portion 31 serves to improve ride comfort and noise performance in a well-balanced manner.

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 34 of the first portion 31 .

As shown in FIG. 2, the non-crossing narrow grooves 17 of the present embodiment include, for example, a first non-crossing narrow groove 18 extending from the first main groove 5 to the crossing narrow groove 16 and a crossing narrow groove extending from the second main groove 6. and a second non-transverse slot 19 extending into the groove 16 . The first non-crossing narrow groove 18 is adjacent to one side of the crossing narrow groove 16 in the tire circumferential direction (the upper side in FIG. 2), and the second non-crossing narrow groove 19 is adjacent to the other side of the crossing narrow groove 16 in the tire circumferential direction. (lower side in FIG. 2).

Each of the first non-crossing narrow groove 18 and the second non-crossing narrow groove 19 preferably crosses the axial center position 10c of the crown land portion 10, and more preferably crosses the tire equator C. Such arrangement of the non-crossing thin grooves 17 can reduce the impact sound when the crown land portion 10 touches the ground and improve the noise performance.

FIG. 7 shows an enlarged view of the first shoulder land portion 11. As shown in FIG. As shown in FIG. 7, it is desirable that the axial width W5 of the first shoulder land portion 11 is larger than the width of the second shoulder land portion 12 . In the present embodiment, the first shoulder land portion 11 has the largest width of the ground contact surface in the axial direction of the three land portions. The axial width W5 of the first shoulder land portion 11 is preferably, for example, 0.25 to 0.40 times the tread width TW. Such a first shoulder land portion 11 can provide a linear steering response during turning, and can improve steering stability.

The land ratio of the first shoulder land portion 11 is larger than the land ratio of the second shoulder land portion 12 . Such a first shoulder land portion 11 exhibits excellent wear resistance. In this specification, the “land ratio” is the ratio of the area of the actual ground contact surface to the area of the virtual ground contact surface in which all the grooves provided in the land portion are filled.

The first shoulder land portion 11 has a plurality of first shoulder lateral grooves 35 with a groove width of more 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 11 . The first shoulder lateral groove 35 crosses, for example, the center position of the first shoulder land portion 11 in the tire axial direction. The axial length L7 of the first shoulder lateral groove 35 is, for example, 0.75 to 0.90 times the axial width W5 of the first shoulder land portion 11 . Such first shoulder lateral grooves 35 serve to improve ride comfort and noise performance 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 main groove 5 and is interrupted within the first shoulder land portion 11 . The first shoulder narrow groove 36 is interrupted, for example, on the first main groove 5 side of the center position of the first shoulder land portion 11 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 L8 of the first shoulder narrow groove 36 is, for example, 0.35 to 0.45 times the axial width W5 of the first shoulder land portion 11 .

FIG. 8 shows a cross-sectional view of the first shoulder narrow groove 36 of FIG. 7 taken along line EE. As shown in FIG. 8, 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 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. 7, each of the first shoulder lateral grooves 35 and the first shoulder narrow grooves 36 extends in a second direction opposite to the first direction with respect to the axial direction of the tire (in FIG. ) is desirable. 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. 9 shows an enlarged view of the second shoulder land portion 12. As shown in FIG. As shown in FIG. 9, the axial width W6 of the second shoulder land portion 12 is at least 0.10 times the tread width TW, preferably 0.20 to 0.30 times the tread width TW. be. Such second shoulder land portion 12 enhances ride comfort and steering stability in a well-balanced manner.

The second shoulder land portion 12 includes a plurality of second shoulder lateral grooves 37 having a groove width greater than 3.0 mm on the ground contact surface, and a plurality of longitudinal grooves 37 communicating with the second shoulder lateral grooves 37 and extending in the tire circumferential direction. A narrow groove 39 is provided. The vertical thin groove 39 has a groove width of 3.0 mm or less on the ground surface. The second shoulder land portion 12 of the present embodiment is provided with a plurality of second shoulder narrow grooves 38 having a groove width of 3.0 mm or less on the ground surface.

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 12 . The axial length L9 of the second shoulder lateral groove 37 is, for example, 0.50 times or more the axial width W6 of the second shoulder land portion 12, and more preferably 0.60 times the tread width TW. 0.80 times. Such second shoulder lateral grooves 37 can improve ride comfort 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 vertical narrow groove 39 of this embodiment communicates with two second shoulder lateral grooves 37 adjacent to each other in the tire circumferential direction. The groove depth of the longitudinal narrow groove 39 is, for example, 1.0 to 2.0 mm. The axial distance L10 from the second tread edge Te2 to the groove centerline of the longitudinal narrow groove 39 is, for example, 0.40 to 0.60 times the axial width W6 of the second shoulder land portion 12. is desirable.

The second shoulder narrow groove 38 extends axially inward from the second tread end Te2. The second shoulder narrow groove 38 intersects the vertical narrow groove 39, for example. 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 groove 38 of this embodiment extends from the second tread end Te2 to the second main groove 6. As shown in FIG.

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.

FIG. 10 shows a cross-sectional view of the second shoulder narrow groove 38 of FIG. 9 taken along line FF. As shown in FIG. 10 , the second shoulder narrow groove 38 includes a shallow portion 38 a having a raised groove bottom on the second main groove 6 side of the vertical narrow groove 39 . The shallow bottom portion 38a of the present embodiment is provided at the end portion of the second shoulder narrow groove 38 on the second main groove 6 side. Such second shoulder narrow grooves 38 serve to improve steering stability and riding comfort in a well-balanced manner.

As shown in FIG. 9, 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. 11 shows a developed view of the tread portion 2 of the tire 1 of another embodiment of the invention. In FIG. 11, elements common to those described above are denoted by the same reference numerals, and descriptions thereof are omitted here.

This embodiment eliminates the second portion 32 of the non-transverse slot 17 . Each non-crossing thin groove 17 has a width of 1.5 mm or less as a whole. Also, the opening 26 shown in FIG. 3 is provided in the first shoulder thin groove 36 . Such an embodiment can improve the wear resistance of the crown land portion 10 compared to the embodiment shown in FIG.

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 195/65R15 having the basic tread pattern shown in FIG. As a comparative example, a tire having a crown land portion a shown in FIG. 12 was produced as a trial. As shown in FIG. 12, the crown land portion a of the tire of the comparative example is provided with only the crossing narrow grooves b, and is not provided with non-crossing narrow grooves. The tire of the comparative example is the same as that shown in FIG. 1 except for the above configuration. Each test tire was tested for ride comfort and noise performance. Common specifications and test methods for each test tire are as follows.
Mounting rim: 15 x 6.0
Tire internal pressure: 200kPa
Test vehicle: 2000cc displacement, front-wheel drive Tire mounting position: All wheels

<Riding comfort>
Riding comfort when the test vehicle was run on a dry road surface was evaluated by the driver's senses. The results are scored with the riding comfort of the comparative example being 100, and the larger the number, the better the riding comfort.

<Noise performance>
The test vehicle was run on a dry road surface at 40 to 100 km/h, and the maximum sound pressure of the noise at this time was measured. The results are indexed with the sound pressure of the comparative example being 100, and the smaller the numerical value, the smaller the noise during running, indicating that excellent noise performance is exhibited.
The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example exhibits ride comfort equivalent to that of the comparative example and exhibits superior noise performance to that of the comparative example.

2 tread portion 3 main groove 4 land portion 5 first main groove 6 second main groove 10 crown land portion 16 crossing narrow groove 17 non-crossing narrow groove Te1 first tread edge Te2 second tread edge

Claims (8)

A tire including a tread portion,
The tread portion includes a first tread edge and a second tread edge, and two main grooves extending continuously in the tire circumferential direction between the first tread edge and the second tread edge; It consists of three land parts divided into main grooves,
The main groove is composed of a first main groove arranged between the tire equator and the first tread edge, and a second main groove arranged between the tire equator and the second tread edge,
the land portion includes a crown land portion between the first main groove and the second main groove;
The crown land portion is provided with a plurality of crossing thin grooves that cross the crown land portion and a plurality of non-crossing thin grooves that extend from one of the main grooves and do not cross the crown land portion ,
The non-crossing narrow grooves include first non-crossing narrow grooves extending from the first main grooves to the crossing narrow grooves, and second non-crossing narrow grooves extending from the second main grooves to the crossing narrow grooves.
tire. A tire including a tread portion,
The tread portion includes a first tread edge and a second tread edge, and two main grooves extending continuously in the tire circumferential direction between the first tread edge and the second tread edge; It consists of three land parts divided into main grooves,
The main groove is composed of a first main groove arranged between the tire equator and the first tread edge, and a second main groove arranged between the tire equator and the second tread edge,
the land portion includes a crown land portion between the first main groove and the second main groove;
The crown land portion is provided with a plurality of crossing thin grooves that cross the crown land portion and a plurality of non-crossing thin grooves that extend from one of the main grooves and do not cross the crown land portion,
The non-transverse narrow groove includes a first portion extending along the transverse narrow groove from the main groove and a second portion bending from the first portion and extending to the transverse narrow groove,
tire. The first portion has a narrow portion having a width of 1.5 mm or less in a cross section orthogonal to the longitudinal direction, and a width larger than that of the narrow portion. 3. The tire of claim 2, including an opening that opens to the tread of the crown land. The tire according to claim 2 or 3, wherein the first portion includes a shallow portion having a raised groove bottom at an end communicating with the main groove. 5. The tire according to any one of claims 1 to 4, wherein each of said crossing narrow grooves and said non-crossing narrow grooves has a groove width of 3.0 mm or less at the contact surface of said crown land portion. The transverse narrow groove has a narrow portion having a width of 1.5 mm or less in a cross section perpendicular to the longitudinal direction, and a narrow portion extending outward in the tire radial direction of the narrow portion and having a width larger than that of the narrow portion. 6. A tire according to any one of claims 1 to 5, comprising an opening that opens onto the ground contact surface of the crown land portion. The crossing thin grooves are arranged between a first shallow portion and a second shallow portion arranged on both sides in the axial direction of the tire, and the first shallow portion arranged between the first shallow portion and the second shallow portion. and a deep portion having a greater depth than the second shallow portion. 8. The tire according to any one of claims 1 to 7, wherein the crown land portion is not provided with grooves having a groove width exceeding 3.0 mm at the contact surface thereof.

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