JP2022104603A - tire - Google Patents

Abstract

To provide a tire in which the steering stability on a dry road surface is improved.SOLUTION: A tire includes a tread portion 2 whose direction of attachment to a vehicle is designated. A land portion 4 of the tread portion 2 includes a crown land portion 13, a first middle land portion 12, and a second middle land portion 14. Under a 50% loaded condition of being rim-assembled to a normal rim at a normal inner pressure, loaded with 50% of the normal load, and grounded to the planar surface at a camber angle 0°, when widths of the ground contact surfaces in the tire axial direction of the first middle land portion 12, the crown land portion 13, and the second middle land portion 14 are respectively W1m, Wc, and W2m, the following formula (1) is satisfied, When the widths in the tire axial direction of an outer ground contact surface 36 and an inner ground contact surface 37 of the crown land portion 13 are respectively Wco and Wci, the following formula (2) is satisfied, W1m>Wc>W2m...(1). Wco>Wci...(2).SELECTED DRAWING: Figure 1

Description

This disclosure relates to tires.

The following Patent Document 1 proposes a pneumatic tire in which a crown land portion and a pair of middle land portions are divided into a tread portion. The crown land portion and the middle land portion are each formed as ribs continuously extending in the tire circumferential direction. The pneumatic tire suppresses noise during traveling due to such characteristics.

Japanese Unexamined Patent Publication No. 2010-132181

Since a large contact pressure acts on the crown land portion and the middle land portion of the tire not only during straight running but also during turning, it greatly contributes to steering stability on dry road surfaces. The developers have found that the above performance can be further improved by reviewing the configuration of these land areas, and have completed this disclosure.

This disclosure has been devised in view of the above problems, and its main task is to provide tires with improved steering stability on dry road surfaces.

The present disclosure is a tire having a tread portion whose mounting direction on a vehicle is specified, and the tread portion is a first tread end that is outside the vehicle when mounted on the vehicle and a second tread portion that is inside the vehicle when mounted on the vehicle. The tread end includes a plurality of circumferential grooves continuously extending in the tire circumferential direction between the first tread end and the second tread end, and a plurality of land portions divided into the circumferential grooves. The plurality of land portions include a crown land portion arranged on the tire equator, a first middle land portion adjacent to the first tread end side of the crown land portion, and a second tread end side of the crown land portion. A 50% load load state in which the rim is assembled to the regular rim with the regular internal pressure, including the second middle land part adjacent to the tire, and a load of 50% of the regular load is applied and the tire is grounded on a flat surface at a camber angle of 0 °. The following equation (1) is satisfied when the widths of the ground contact surfaces of the first middle land portion, the crown land portion, and the second middle land portion in the tire axial direction are W1 m, Wc, and W2 m, respectively. The crown land portion includes an outer ground contact surface on the first tread end side of the tire equatorial line and an inner ground contact surface on the second tread end side of the tire equatorial line, and the tire shaft of the outer ground contact surface and the inner ground contact surface. When the widths in the directions are Wco and Wci, respectively, the tire satisfies the following equation (2).
W1m>Wc> W2m ... (1)
Wco> Wci ... (2)

By adopting the above configuration, the tires of the present disclosure can improve the steering stability on a dry road surface.

It is a development view of the tread part which shows one Embodiment of this disclosure. It is an enlarged view which shows the ground contact surface shape at the time of the ground contact of a tread part. It is an enlarged view of the 1st shoulder land part and the 1st middle land part of FIG. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a sectional view taken along line CC of FIG. FIG. 3 is a sectional view taken along line BB in FIG. FIG. 3 is a sectional view taken along line DD of FIG. It is an enlarged view of the 1st middle land part, the crown land part and the 2nd middle land part of FIG. It is an enlarged view of the 2nd shoulder land part of FIG. 9 is a cross-sectional view taken along the line EE of FIG. FIG. 5 is a cross-sectional view taken along the line FF of FIG. FIG. 3 is a sectional view taken along line GG of FIG. It is an enlarged view of the 1st middle land part of another embodiment. It is an enlarged view of the 1st middle land part of another embodiment. It is a development view of the tread part of the other embodiment of this disclosure. It is an enlarged view of the 1st middle land part of FIG. FIG. 16 is a cross-sectional view taken along the line HH of FIG. It is an enlarged view of the 1st middle land part of another embodiment. It is a development view of the tread part of a reference tire. It is a development view of the tread part of the tire of the comparative example.

Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present disclosure. The tire 1 of the present embodiment is suitably used as, for example, a pneumatic tire for a passenger car. However, the present disclosure is not limited to such an aspect, and may be applied to a pneumatic tire for heavy load and a non-pneumatic tire in which the inside of the tire is not filled with pressurized air.

As shown in FIG. 1, the tire 1 of the present disclosure has a tread portion 2 having a designated orientation for mounting on a vehicle. The tread portion 2 has a first tread end T1 intended to be located on the outside of the vehicle when the tire 1 is mounted on the vehicle, and a second tread end T2 intended to be located on the inside of the vehicle when the tire 1 is mounted on the vehicle. The orientation of mounting on the vehicle is indicated by characters or symbols on the sidewall portion (not shown), for example.

The first tread end T1 and the second tread end T2 correspond to the outermost contact positions in the tire axial direction when 50% of the normal load is applied to the tire 1 in the normal state and the tire 1 touches the plane at a camber angle of 0 °. do.

The "normal state" is a state in which, in the case of a pneumatic tire for which various standards are defined, the tire is rim-assembled on a normal rim, the normal internal pressure is filled, and there is no load. In the case of tires for which various standards are not defined or non-pneumatic tires, the normal state means a standard usage state according to the purpose of use of the tire, which is not mounted on the vehicle and has no load. .. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATTA and "Design Rim" for TRA. If it is ETRTO, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATTA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based, in the case of pneumatic tires with various standards, and in the case of JATTA, "maximum" Load capacity ", the maximum value shown in the table" TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "for TRA, and" LOAD CAPACITY "for ETRTO. Further, in the case of a tire for which various standards are not defined or a non-pneumatic tire, the "regular load" refers to the load acting on one tire in the standard mounted state of the tire. The "standard mounting state" refers to a state in which a tire is mounted on a standard vehicle according to the purpose of use of the tire and the vehicle is stationary on a flat road surface in a state in which the vehicle can travel.

The tread portion 2 includes a plurality of circumferential grooves 3 continuously extending in the tire circumferential direction between the first tread end T1 and the second tread end T2, and a plurality of land portions 4 divided into the circumferential grooves. Have. The tire 1 of the present embodiment is configured as a so-called 5-rib tire including five land portions 4 in which the tread portion 2 is divided into four circumferential grooves 3.

The circumferential groove 3 includes, for example, a first shoulder circumferential groove 5, a second shoulder circumferential groove 8, a first crown circumferential groove 6, and a second crown circumferential groove 7. The first shoulder circumferential groove 5 is provided between the first tread end T1 and the tire equator C. The second shoulder circumferential groove 8 is provided between the second tread end T2 and the tire equator C. The first crown circumferential groove 6 is provided between the first shoulder circumferential groove 5 and the tire equator C. The second crown circumferential groove 7 is provided between the second shoulder circumferential groove 8 and the tire equator C.

The distance L1 in the tire axial direction from the tire equator C to the groove center line of the first shoulder circumferential groove 5 or the second shoulder circumferential groove 8 is preferably, for example, 25% to 35% of the tread width TW. The distance L2 in the tire axial direction from the tire equator C to the groove center line of the first crown circumferential groove 6 or the second crown circumferential groove 7 is preferably, for example, 5% to 15% of the tread width TW. The tread width TW is the distance in the tire axial direction from the first tread end T1 to the second tread end T2 in the normal state.

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

It is desirable that the groove width W1 of each circumferential groove 3 is, for example, 2.0% to 8.0% of the tread width TW. In the present embodiment, the first shoulder circumferential groove 5 has the smallest groove width among the four circumferential grooves 3. However, the present disclosure is not limited to such an embodiment. The depth of each circumferential groove 3 is preferably 5 to 10 mm, for example, in the case of a pneumatic tire for a passenger car.

The land portion 4 of the present disclosure includes a crown land portion 13, a first middle land portion 12, and a second middle land portion 14. The crown land portion 13 is arranged on the tire equator C, and is divided between the first crown circumferential groove 6 and the second crown circumferential groove 7. The first middle land portion 12 is adjacent to the first tread end T1 side of the crown land portion 13, and is divided into a first shoulder circumferential groove 5 and a first crown circumferential groove 6. The second middle land portion 14 is adjacent to the second tread end T2 side of the crown land portion 13, and is divided into a second shoulder circumferential groove 8 and a second crown circumferential groove 7.

The land portion 4 of the present embodiment further includes a first shoulder land portion 11 and a second shoulder land portion 15. The first shoulder land portion 11 includes the first tread end T1 and is adjacent to the first tread end T1 side of the first middle land portion 12. The second shoulder land portion 15 includes the second tread end T2 and is adjacent to the second tread end T2 side of the second middle land portion 14.

FIG. 2 shows an enlarged view showing the shape of the ground contact surface of the tread portion 2 when it is in contact with the ground. As shown in FIG. 2, the first shoulder land is in a 50% load load state in which the rim is assembled to the regular rim at the regular internal pressure and 50% of the regular load is applied to the ground at a camber angle of 0 °. The widths of the contact patches in the tire axial direction of the portion 11, the first middle land portion 12, the crown land portion 13, the second middle land portion 14, and the second shoulder land portion 15 are set to W1s, W1m, Wc, W2m, and W2s, respectively. Then, the following equation (1) is satisfied.
W1m>Wc> W2m ... (1)

As shown in FIG. 1, the crown land portion 13 includes an outer contact patch 36 on the first tread end T1 side of the tire equator C and an inner contact patch 37 on the second tread end side of the tire equator C. In the present disclosure, the following equation (2) is satisfied when the widths of the outer contact patch 36 and the inner contact patch 37 in the tire axial direction are Wco and Wci, respectively.
Wco> Wci ... (2)

In the present disclosure, by adopting the above configuration, it is possible to improve the steering stability on a dry road surface while ensuring various performances of the tire including wet performance. The following mechanism is inferred as the reason.

With the above configuration, in the tire 1 of the present disclosure, the rigidity of each land portion of the tread portion 2 increases toward the outside of the vehicle, whereby the cornering force linearly increases as the steering angle amount increases. Improves steering stability on dry roads. In particular, since the crown land portion 13 satisfies the above equation (2), the above effect is surely exhibited. It is presumed that the tires of the present disclosure can improve steering stability on dry road surfaces by the above mechanism.

Hereinafter, a more detailed configuration of the present embodiment will be described. It should be noted that each configuration described below shows a specific embodiment of the present embodiment. Therefore, it goes without saying that the present disclosure can exert the above-mentioned effects even if it does not have the configuration described below. Further, even if any one of the configurations described below is independently applied to the tire of the present disclosure having the above-mentioned characteristics, improvement in performance according to each configuration can be expected. Further, when some of the configurations described below are applied in combination, it is expected that the composite performance will be improved according to each configuration.

It is desirable that the tire 1 of the present embodiment satisfies the following equation (3) under a 50% load load state. Such a tire 1 has a greater rigidity in the land portion near the first tread end T1. Therefore, even when the center of the ground contact surface is moved to the first tread end T1 side by steering, the steering response is stable and the cornering force is linearly generated with respect to the increase in the steering angle. Therefore, the tire 1 of the present embodiment can further improve the steering stability on a dry road surface (hereinafter, may be simply referred to as "steering stability").
W1s>W1m>Wc> W2m ≧ W2s… (3)

Under a 50% load load condition, the width W1s of the ground contact surface of the first shoulder land portion 11 in the tire axial direction is preferably 115% to 125% of the width Wc of the ground contact surface of the crown land portion 13 in the tire axial direction. .. As a result, the rigidity of the first shoulder land portion 11 is optimized, and the noise performance can be improved in addition to the above-mentioned effects.

From the same viewpoint, the width W1 m in the tire axial direction of the ground contact surface of the first middle land portion 12 is 101% to 107% of the width Wc of the ground contact surface in the tire axial direction of the crown land portion 13 under a 50% load load condition. Is desirable.

Under a 50% load load condition, the width W2m of the ground contact surface of the second middle land portion 14 in the tire axial direction is preferably 90% to 99% of the width Wc of the ground contact surface of the crown land portion 13 in the tire axial direction. .. This improves the noise performance when going straight. In addition, the vibration of the tire when going straight is less likely to be transmitted to the vehicle body side, and the riding comfort is also improved.

From the same viewpoint, the width W2s of the ground contact surface of the second shoulder land portion 15 in the tire axial direction is 90% to 99% of the width Wc of the ground contact surface of the crown land portion 13 in the tire axial direction under a 50% load load condition. Is desirable.

As a more desirable embodiment, in the present embodiment, the width W2m of the second middle land portion 14 is the same as the width W2s of the second shoulder land portion 15 under a 50% load load state. As a result, the progress of wear between the second middle land portion 14 and the second shoulder land portion 15 becomes uniform, and the uneven wear resistance performance is improved.

As shown in FIG. 1, a sipe 16 is provided in each land portion 4 of the embodiment. As used herein, the term "sipe" refers to a notch element having a small width and having a width of 1.5 mm or less between two sipe walls in the main body of the sipe 16. The width of the sipe 16 is preferably 0.2 to 1.2 mm, more preferably 0.5 to 1.0 mm. The sipe 16 may include a widening portion that opens with a width larger than the width and a flask bottom portion that is larger than the width.

FIG. 3 shows an enlarged view of the first shoulder land portion 11 and the first middle land portion 12. As shown in FIG. 3, the first shoulder land portion 11 is provided with only sipes. As a result, the rigidity of the first shoulder land portion 11 is increased. In the present embodiment, the first shoulder land portion 11 is provided with a plurality of first shoulder sipes 21 extending in the tire axial direction.

The one-pitch length P1 in the tire circumferential direction of the first shoulder sipe 21 is, for example, 100% to 130% of the width W3 of the tread in the tire axial direction of the first shoulder land portion 11. The length of one pitch of the two sipes in the tire circumferential direction is a distance parallel to the tire circumferential direction from the center position in the width direction in the cross section of one sipe to the center position of the other sipes. When the distance changes in the tire axis direction, the intermediate distance corresponds to the one pitch length.

It is desirable that the first shoulder sipe 21 communicates with at least the first shoulder circumferential groove 5. The first shoulder sipe 21 of the present embodiment extends from, for example, the first shoulder circumferential groove 5 to the first tread end T1 and completely crosses the tread of the first shoulder land portion 11. However, the first shoulder sipe 21 is not limited to such an aspect, and may have a break in the first shoulder land portion 11.

The first shoulder sipe 21 is inclined in the first direction (upward to the right in each drawing of the present specification) with respect to the tire axial direction, for example. The angle of the first shoulder sipe 21 with respect to the tire axial direction is, for example, 5 to 35 °. In a more preferred embodiment, the first shoulder sipe 21 includes a portion where the angle with respect to the tire axial direction increases toward the second tread end T2 side. Such a first shoulder sipe 21 can exert a frictional force also in the tire axial direction.

The opening width W4 on the tread of the first shoulder sipe 21 is larger than, for example, the opening width W5 on the tread of the first middle sipe 30. Specifically, the opening width W4 of the first shoulder sipe 21 is, for example, 4.0 to 8.0 mm. The opening width W5 of the first middle sipe 30 is, for example, 2.0 to 6.0 mm. Further, the opening width W5 of the first middle sipe 30 is 50% to 90% of the opening width W4 of the first shoulder sipe 21. Such a first shoulder sipe 21 and a first middle sipe 30 can improve uneven wear resistance.

FIG. 4 shows a sectional view taken along line AA of FIG. 3 as a diagram showing a cross section of the first shoulder sipe 21. As shown in FIG. 4, the first shoulder sipe 21 includes a main body portion 21a extending in the radial direction of the tire and a widening portion 21b that is open at the tread surface of the land portion and has a width larger than that of the main body portion 21a. In the present embodiment, the width of the main body is, for example, 0.5 to 1.5 mm.

The widened portion 21b of the first shoulder sipe 21 includes an inclined surface 22 extending from the main body portion 21a to the tread surface. The inclined surface 22 of the present embodiment is planar and is inclined at an angle θ1 of 50 to 70 ° with respect to the radial direction of the tire. Since the entire surface of the inclined surface 22 can be grounded in such a widening portion 21b when a large ground contact pressure acts on the land portion, the substantial ground contact area of the tread portion is surely expanded. Therefore, the steering stability is further improved.

The depth d1 of the widened portion 21b of the first shoulder sipe 21 is 10% to 30% of the maximum depth d3 of the first shoulder sipe 21, and in a preferred embodiment, it is 0.5 to 2.0 mm. The maximum depth d3 of the first shoulder sipe 21 is, for example, 70% to 100% of the depth of the circumferential groove 3.

The width W6 (the width along the tread in the cross section of the sipe) of the widened portion 21b of the first shoulder sipe 21 is, for example, 2.0 to 4.0 mm.

FIG. 5 shows a sectional view taken along line CC of FIG. As shown in FIG. 5, the first shoulder sipe 21 includes a shallow bottom portion 23 with a locally raised bottom. The shallow bottom portion 23 of the present embodiment is provided, for example, in a communication portion with the first shoulder circumferential groove 5. The minimum depth d4 of the shallow bottom 23 of the first shoulder sipe 21 is 40% to 60% of the maximum depth d3 of the first shoulder sipe 21. The length L3 of the shallow bottom portion 23 in the tire axial direction is 10% to 30% of the width W3 (shown in FIG. 3) of the first shoulder land portion 11 in the tire axial direction. The length L3 of the shallow bottom portion 23 is measured, for example, at the center position of the shallow bottom portion 23 in the height direction. The first shoulder sipe 21 having such a shallow bottom portion 23 maintains the rigidity of the first shoulder land portion 11 and improves steering stability.

As shown in FIG. 3, the first middle land portion 12 includes a first vertical edge 12a on the first tread end T1 side, a second vertical edge 12b on the second tread end T2 side, and a first vertical edge 12a. Includes a tread between the second vertical edge 12b. Further, only the sipe is provided in the first middle land portion 12. As a result, the rigidity of the first middle land portion 12 is increased. The first middle land portion 12 of the present embodiment is provided with a plurality of first middle sipes 30 extending in the tire axial direction.

FIG. 6 shows a sectional view taken along line BB of FIG. 3 as a diagram showing a cross section of the first middle sipe 30. As shown in FIG. 6, the first middle sipe 30 includes a main body portion 30a extending in the radial direction of the tire, and a widening portion 30b that is open at the tread of the land portion and has a width larger than that of the main body portion 30a. In the present embodiment, the width of the main body is, for example, 0.5 to 1.5 mm.

The widening portion 30b of the first middle sipe 30 includes an inclined surface 25 extending from the main body portion 30a to the tread surface. The inclined surface 25 of the present embodiment is planar and is inclined at an angle θ2 of 30 to 60 ° with respect to the radial direction of the tire.

The depth d2 of the widened portion 30b of the first middle sipe 30 is 15% to 30% of the maximum depth d5 of the first middle sipe 30. Further, the depth d2 of the widening portion 30b of the first middle sipe 30 is, for example, 1.0 to 3.0 mm. In a more preferred embodiment, the depth d1 of the widened portion 21b of the first shoulder sipe 21 is smaller than the depth d2 of the widened portion 30b of the first middle sipe 30. The depth d1 of the widened portion 21b of the first shoulder sipe 21 is 50% to 90%, preferably 60% to 80% of the depth d2 of the widened portion 30b of the first middle sipe 30.

The width W8 (the width along the tread in the cross section of the sipe) of the widened portion 30b of the first middle sipe 30 is, for example, 1.0 to 3.0 mm.

The first middle sipe 30 extends from the first vertical edge 12a and has a break 31a in the first middle land portion 12 and an outer first middle sipe 31 and extends from the second vertical edge 12b and into the first middle land portion 12. Includes an inner first middle sipe 32 having a break 32a.

The first middle sipe 30 extends linearly in a tread plan view. Further, the first middle sipe 30 is inclined in the first direction with respect to the tire axial direction. More specifically, each of the outer first middle sipe 31 and the inner first middle sipe 32 extends linearly in the tread plan view and is inclined in the first direction with respect to the tire axial direction.

The angle of the outer first middle sipe 31 with respect to the tire axial direction and the angle of the inner first middle sipe 32 with respect to the tire axial direction are preferably 20 ° or more, more preferably 25 ° or more, and preferably 45 ° or less, respectively. More preferably, it is 40 ° or less. Such an outer first middle sipe 31 and an inner first middle sipe 32 provide a well-balanced frictional force in the tire axial direction and the tire circumferential direction.

The angle difference between the outer first middle sipe 31 and the inner first middle sipe 32 is preferably 10 ° or less, more preferably 5 ° or less, and these are arranged in parallel in the present embodiment. Such an outer first middle sipe 31 and an inner first middle sipe 32 can suppress uneven wear of the first middle land portion 12.

The outer first middle sipe 31 and the inner first middle sipe 32 are interrupted without crossing the center position of the first middle land portion 12 in the tire axial direction, respectively. The tire axial length La of the outer first middle sipe 31 is 20% or more, more preferably 25% or more, preferably 45% or less, more preferably 45% or more of the tire axial width W7 of the first middle land portion 12. Is 40% or less. Similarly, the length Lc in the tire axial direction of the inner first middle sipe 32 is 20% or more, more preferably 25% or more, preferably 45% or less of the width W7 in the tire axial direction of the first middle land portion 12. , More preferably 40% or less. Such an outer first middle sipe 31 and an inner first middle sipe 32 can improve ride quality and noise performance while maintaining steering stability.

The break end 31a of the outer first middle sipe 31 and the break end 32a of the inner first middle sipe 32 are misaligned in the tire circumferential direction. The distance Lb in the tire circumferential direction between the interrupted end 31a of the outer first middle sipe 31 and the interrupted end 32a of the inner first middle sipe 32 is, for example, 50% or less of one pitch length P2 in the tire circumferential direction of the first middle sipe 30. It is preferably 25% to 40%. In a more desirable embodiment, the distance Lb is in the range of the following equation (4). As a result, the pitch sound of each sipe is likely to become white noise, and the noise performance is improved.
Lb = 2La ± 1 (mm) ... (4)

The 1-pitch length P2 of the first middle sipe 30 is, for example, 80% to 120% of the 1-pitch length P1 of the first shoulder sipe 21, and in a more desirable embodiment, these are the same.

In the present embodiment, the outer first middle sipe 31 communicates with the first shoulder circumferential groove 5. Further, in the tread plan view, the widened portion of the outer first middle sipe 31 overlaps with the region where the widened portion 21b of the first shoulder sipe 21 is extended along the length direction thereof. As a result, the outer first middle sipe 31 and the first shoulder sipe 21 work together to further improve the wet performance.

The first middle sipe 30 has a certain depth in the length direction thereof. More specifically, the outer first middle sipe 31 and the inner first middle sipe 32 each have a certain depth in the length direction thereof. The depth of the inner first middle sipe 32 is, for example, 70% to 100% of the depth of the circumferential groove 3. Further, the maximum depth of the outer first middle sipe 31 is smaller than the maximum depth of the inner first middle sipe 32. The maximum depth of the outer first middle sipe 31 is 30% to 70% of the maximum depth of the inner first middle sipe 32, preferably 1.0 to 2.5 mm.

The cross-sectional shape of the sipe shown in FIG. 6 can be applied to the outer first middle sipe 31 and the inner first middle sipe 32, respectively. Such an outer first middle sipe 31 and an inner first middle sipe 32 make the pitch sound of each sipe white noise to improve noise performance, and improve ride comfort and steering stability in a well-balanced manner.

As shown in FIG. 3, the first middle land portion 12 is provided with, for example, a first vertical sipe 33 extending in the tire circumferential direction. The first vertical sipe 33 of the present embodiment continuously extends in the tire circumferential direction. Such a first vertical sipe 33 provides a frictional force in the tire axial direction during wet running. Still another embodiment of the first vertical sipe 33 will be described later.

The first vertical sipe 33 is provided in, for example, a central region when the first middle land portion 12 is divided into three equal parts in the tire axial direction. The distance in the tire axial direction from the first vertical sipe 33 to the center position in the tire axial direction of the first middle land portion 12 is preferably 10% or less of the width W7 in the tire axial direction of the first middle land portion 12, which is more desirable. Is less than 5%. Such an arrangement of the first vertical sipes 33 can suppress uneven wear of the first middle land portion 12.

FIG. 7 shows a sectional view taken along line DD of FIG. As shown in FIG. 7, the first vertical sipe 33 is configured with, for example, a constant width from the end of the opening toward the bottom.

FIG. 8 shows an enlarged view of the first middle land portion 12, the crown land portion 13, and the second middle land portion 14. As shown in FIG. 8, the crown land portion 13 has a first vertical edge 13a on the first tread end T1 side, a second vertical edge 13b on the second tread end T2 side, and a first vertical edge 13a and a second. Includes treads to and from the vertical edges 13b. Similarly, the second middle land portion 14 includes a first vertical edge 14a on the first tread end T1 side, a second vertical edge 14b on the second tread end T2 side, a first vertical edge 14a, and a second vertical edge 14b. Including the tread between and.

The width Wco of the outer ground contact surface 36 in the tire axial direction is, for example, 51% to 60%, preferably 51% to 55% of the width W9 of the ground contact surface of the crown land portion 13 in the tire axial direction. As a result, the steering stability is improved while the uneven wear of the crown land portion 13 is suppressed.

Only the sipe is provided on the land portion 13 of the crown. As a result, the rigidity of the crown land portion 13 is increased.

The crown land portion 13 is provided with a plurality of crown sipes 40 inclined in a second direction (downward to the right in each drawing of the present specification) opposite to the first direction with respect to the tire axial direction. Has been done. The crown sipe 40 of the present embodiment is inclined in the second direction and extends linearly. Such a crown sipe 40 cooperates with the first middle sipe 30 to provide frictional force in multiple directions and improve wet performance.

The one-pitch length P3 in the tire circumferential direction of the crown sipe 40 is, for example, 80% to 120% of the one-pitch length P2 (shown in FIG. 3) of the first middle sipe 30 in the tire circumferential direction. , These are the same. Such a sipe arrangement improves uneven wear resistance.

The angle of the crown sipe 40 with respect to the tire axial direction is preferably 20 ° or more, more preferably 25 ° or more, preferably 45 ° or less, and more preferably 40 ° or less. The crown sipe 40 provides a well-balanced frictional force in the tire circumferential direction and the tire axial direction.

The crown sipe 40 has an outer crown sipe 41 that extends from the first vertical edge 40a and has a break 41a in the crown land portion 13 and an inner side that extends from the second vertical edge 40b and has a break 42a in the crown land portion 13. Including the crown sipe 42.

The angle difference between the outer crown sipe 41 and the inner crown sipe 42 is preferably 10 ° or less, more preferably 5 ° or less, and these are arranged in parallel in the present embodiment. Such an outer crown sipe 41 and an inner crown sipe 42 suppress uneven wear of the crown land portion 13.

The outer crown sipe 41 and the inner crown sipe 42 are interrupted without crossing the center position of the crown land portion 13 in the tire axial direction, respectively. The tire axial length L4 of the outer crown sipe 41 and the tire axial length L5 of the inner crown sipe 42 are, for example, 20% to 35% of the tire axial width W9 of the crown land portion 13. .. Such an outer crown sipe 41 and an inner crown sipe 42 improve steering stability and ride comfort in a well-balanced manner.

The break end 41a of the outer crown sipe 41 and the break end 42a of the inner crown sipe 42 are misaligned in the tire circumferential direction. The distance L6 between the break end 41a of the outer crown sipe 41 and the break end 42a of the inner crown sipe 42 in the tire circumferential direction is, for example, the break end 31a of the outer first middle sipe 31 and the break end 32a of the inner first middle sipe 32. It is desirable that the distance is smaller than the distance Lb in the tire circumferential direction. Specifically, the distance L6 is preferably 70% or less, more preferably 60% or less, preferably 30% or more, and more preferably 40% or more of the distance Lb. Such an arrangement of sipes makes the pitch sound of each sipes white noise and improves the noise performance.

The outer crown sipe 41 and the inner crown sipe 42 each have a certain depth in the length direction thereof. The depth of the inner crown sipe 42 is, for example, 70% to 100% of the depth of the circumferential groove 3. Also, the maximum depth of the outer crown sipe 41 is smaller than the maximum depth of the inner crown sipe 42. The maximum depth of the outer crown sipe 41 is 30% to 70% of the maximum depth of the inner crown sipe 42, preferably 1.0 to 2.5 mm.

The cross-sectional shape configuration of the first middle sipe 30 described with reference to FIG. 6 can be applied to the outer crown sipe 41 and the inner crown sipe 42, respectively. Therefore, the description here is omitted.

Only the sipes are provided in the second middle land portion 14. As a result, the rigidity of the second middle land portion 14 is increased.

The second middle land portion 14 is provided with a plurality of second middle sipes 45 inclined in the second direction with respect to the tire axial direction. The second middle sipe 45 of the present embodiment is inclined in the second direction and extends linearly.

The 1-pitch length P4 in the tire circumferential direction of the second middle sipe 45 is, for example, 80% to 120% of the 1-pitch length P3 in the tire circumferential direction of the crown sipe 40, and in the present embodiment, these are the same. ing. Such a sipe arrangement improves uneven wear resistance.

The angle of the second middle sipe 45 with respect to the tire axial direction is preferably 20 ° or more, more preferably 25 ° or more, preferably 45 ° or less, and more preferably 40 ° or less. The crown sipe 40 provides a well-balanced frictional force in the tire circumferential direction and the tire axial direction.

The second middle sipe 45 has an outer second middle sipe 46 extending from the first vertical edge 14a and having a break end 46a in the crown land portion 13, and a break end 47a extending from the second vertical edge 14b and having a break end 47a in the crown land portion 13. Includes an inner second middle sipe 47 and has.

The angle difference between the outer second middle sipe 46 and the inner second middle sipe 47 is preferably 10 ° or less, more preferably 5 ° or less, and these are arranged in parallel in the present embodiment. Such an outer second middle sipe 46 and an inner second middle sipe 47 suppress uneven wear of the second middle land portion 14.

The outer second middle sipe 46 and the inner second middle sipe 47 are interrupted without crossing the center position of the second middle land portion 14 in the tire axial direction, respectively. The tire axial length L7 of the outer second middle sipe 46 and the tire axial length L8 of the inner second middle sipe 47 are, for example, the length L4 of the outer crown sipe 41 and the length of the inner crown sipe 42. It is larger than L5. Further, it is desirable that the length L7 in the tire axial direction of the outer second middle sipe 46 and the length L8 in the tire axial direction of the inner second middle sipe 47 are larger than the length in the tire axial direction of the first middle sipe 30. Specifically, the length L7 of the outer second middle sipe 46 and the length L8 of the inner second middle sipe 47 are 25% to 35% of the tire axial width W10 of the second middle land portion 14. Such an outer second middle sipe 46 and an inner second middle sipe 47 are useful for improving wet performance and riding comfort.

The break end 46a of the outer second middle sipe 46 and the break end 47a of the inner second middle sipe 47 are misaligned in the tire circumferential direction. The distance L9 between the break end 46a of the outer second middle sipe 46 and the break end 47a of the inner second middle sipe 47 in the tire circumferential direction is, for example, the break end 31a of the outer first middle sipe 31 and the break end 32 of the inner first middle sipe 32. It is smaller than the tire circumferential distance Lb from 32a, and preferably smaller than the tire circumferential distance L6 between the break end 41a of the outer crown sipe 41 and the break end 42a of the inner crown sipe 42. Specifically, the distance L9 is preferably 80% or less, more preferably 70% or less, preferably 40% or more, and more preferably 50% or more of the distance L6. Such an arrangement of sipes optimizes the rigidity balance of each land area and improves steering stability and riding comfort in a well-balanced manner.

The outer second middle sipe 46 and the inner second middle sipe 47 each have a certain depth in the length direction thereof. The depth of the inner second middle sipe 47 is, for example, 70% to 100% of the depth of the circumferential groove 3. Further, the maximum depth of the outer second middle sipe 46 is smaller than the maximum depth of the inner second middle sipe 47. The maximum depth of the outer second middle sipe 46 is 30% to 70% of the maximum depth of the inner second middle sipe 47, preferably 1.0 to 2.5 mm. Such an outer crown sipe 41 and an inner crown sipe 42 convert the pitch sound of each sipe into white noise to improve noise performance, and improve ride comfort and steering stability in a well-balanced manner.

The cross-sectional shape configuration of the first middle sipe 30 described with reference to FIG. 6 can be applied to the outer second middle sipe 46 and the inner second middle sipe 47, respectively. Therefore, the description here is omitted.

The second middle land portion 14 is provided with, for example, a second vertical sipe 48 extending in the tire circumferential direction. The second vertical sipe 48 of the present embodiment continuously extends in the tire circumferential direction. Further, the second vertical sipe 48 has the same cross-sectional shape as the above-mentioned first vertical sipe 33. Such a second vertical sipe 48 provides a frictional force in the tire axial direction.

The second vertical sipe 48 is provided in, for example, a central region when the second middle land portion 14 is divided into three equal parts in the tire axial direction. The distance in the tire axial direction from the second vertical sipe 48 to the center position in the tire axial direction of the second middle land portion 14 is preferably 10% or less of the width W10 in the tire axial direction of the second middle land portion 14, which is more desirable. Is less than 5%.

FIG. 9 shows an enlarged view of the second shoulder land portion 15 of FIG. As shown in FIG. 9, the second shoulder land portion 15 is provided with only sipes. As a result, the rigidity of the second middle land portion 14 is increased.

The second shoulder land portion 15 is provided with, for example, a plurality of second shoulder sipes 50 extending in the tire axial direction. In the present embodiment, the total number of the second shoulder sipes 50 is larger than the total number of the first shoulder sipes 21 (shown in FIG. 3, hereinafter the same). Such a sipe arrangement improves noise performance and wet performance.

In order to improve noise performance and wet performance while maintaining steering stability, the total number of second shoulder sipes 50 is preferably 1.3 times the total number of first shoulder sipes 21 (shown in FIG. 3). As described above, it is more preferably 1.5 times or more, further preferably 1.8 times or more, preferably 2.8 times or less, more preferably 2.5 times or less, and further preferably 2.2 times or less.

The one-pitch length P5 in the tire circumferential direction of the second shoulder sipe 50 is, for example, 30% to 70% of the one-pitch length P4 (shown in FIG. 8) in the tire circumferential direction of the second middle sipe 45.

The second shoulder sipe 50 is inclined in the first direction, for example. That is, the first shoulder sipe 21 and the second shoulder sipe 50 are inclined in the same direction with respect to the tire axial direction. The second shoulder sipe 50 of the present embodiment is inclined in the first direction and extends linearly.

The angle of the second shoulder sipe 50 with respect to the tire axial direction is, for example, 20 ° or less, preferably 15 ° or less, and more preferably 10 ° or less. Thereby, in the present embodiment, the maximum angle of the first shoulder sipe 21 with respect to the tire axial direction is larger than the maximum angle of the second shoulder sipe 50 with respect to the tire axial direction. By arranging such sipes, the noise performance is further improved.

To the second shoulder sipe 50, the configuration of the cross-sectional shape of the first shoulder sipe 21 described with reference to FIG. 4 can be applied. Therefore, the description here is omitted.

The second shoulder sipe 50 is, for example, a crossing second shoulder sipe 51 that completely crosses the second shoulder land portion 15 in the tire axial direction, and a second shoulder sipe 51 that extends in the tire axial direction from at least the second tread end T2 and is the second shoulder land portion. Includes a break second shoulder sipe 52 having a break within 15.

The interrupted second shoulder sipe 52 has a longer length in the tire axial direction than any of the first middle sipe 30, the crown sipe 40, and the second middle sipe 45. The tire axial length L10 of the second shoulder sipe 50 is preferably 50% or more, more preferably 60% or more, preferably 90% or less, of the tire axial width W11 of the second shoulder land portion 15. More preferably, it is 80% or less. The interrupted second shoulder sipe 52 improves ride comfort and steering stability in a well-balanced manner.

FIG. 10 shows a sectional view taken along line EE of FIG. As shown in FIG. 10, the transverse second shoulder sipe 51 includes a shallow bottom 53 with a locally raised bottom. The shallow bottom portion 53 of the present embodiment is provided, for example, in a communication portion with the second shoulder circumferential groove 8. The configuration of the shallow bottom portion 23 (shown in FIG. 6) of the first shoulder sipe 21 can be applied to the shallow bottom portion 53 of the second shoulder sipe 50, and the description thereof is omitted here. The transverse second shoulder sipe 51 including such a shallow bottom portion 53 maintains the rigidity of the second shoulder land portion 15 and improves steering stability.

As shown in FIG. 1, in the present embodiment, only the sipe 16 is provided in each of the five land portions 4, and the horizontal groove for drainage is not provided. As a result, the rigidity of each land portion is maintained, and the pumping noise of the lateral groove is not generated, so that the noise performance is expected to be improved.

As a more desirable embodiment, in the present embodiment, the circumferential groove 3 includes a first groove wall 3a and a second groove wall 3b facing each other, and the first groove wall 3a has a circumferential groove in which the tread surface of the tread portion 2 appears. A plurality of first recesses 56 that are recessed outward in the groove width direction from the groove edge of 3 are provided. Further, the second groove wall 3b is provided with a plurality of second recesses 57 recessed outward in the groove width direction from the groove edge of the circumferential groove 3 in which the tread surface of the tread portion 2 appears. Such a first recess 56 and a second recess 57 can enhance the drainage property of the circumferential groove 3 and effectively suppress the hydroplaning phenomenon. Further, the first recess 56 and the second recess 57 can be expected to have the effect of attenuating the sound pressure of the noise generated by the circumferential groove 3, and are also useful for improving the noise performance.

It is desirable that the amount of the dent from the groove edge of the first recess 56 gradually decreases from the deepest portion recessed outward in the groove width direction toward both sides in the tire circumferential direction. Similarly, it is desirable that the amount of the second recess 57 is gradually reduced from the groove edge toward both sides in the tire circumferential direction from the deepest portion recessed outward in the groove width direction. Such a first recess 56 and a second recess 57 can prevent a portion having a locally reduced rigidity from being formed in the land portion, and can suppress uneven wear of the land portion.

In order to further enhance the above-mentioned effect, it is desirable that the first recesses 56 and the second recesses 57 are provided alternately in the tire circumferential direction.

In the present embodiment, a plurality of sipes communicating with the circumferential groove 3 are provided in the land portion, and the first recess is between 1.0 to 3.0 times the length of one pitch of the sipes. 56 and a second recess 57 are provided one by one. In other words, the tire circumferential length of the pair of the first recesses 56 and the second recesses 57 is 1.0 to 3.0 times the length of one pitch of the sipes. As a result, the noise performance is improved while maintaining the rigidity of the land portion.

FIG. 11 shows a sectional view taken along line FF of FIG. FIG. 12 shows a sectional view taken along line GG of FIG. As shown in FIGS. 11 and 12, the first groove wall 3a and the second groove wall 3b have substantially the same shape. Further, the first recess 56 and the second recess 57 have substantially the same shape. Therefore, the configuration of the first groove wall 3a described below can be applied to the second groove wall 3b. Further, the configuration of the first recess 56 can be applied to the second recess 57.

The first groove wall 3a includes an outer portion 18 extending from the groove edge of the circumferential groove 3 inwardly in the radial direction of the tire in a direction in which the groove width is reduced. Further, the first groove wall 3a includes an inner portion 19 extending from the outer portion 18 toward the inside in the radial direction of the tire in a direction of increasing the groove width and continuing to the groove bottom portion. The inner portion 19 constitutes the bottom surface of the first recess 56.

The height h1 of the first recess 56 in the tire radial direction is, for example, 30% to 70%, preferably 40% to 60% of the total depth d6 of the circumferential groove 3. Such a first recess 56 can improve wet performance and noise performance while suppressing uneven wear on land.

From the same viewpoint, the depth d7 of the first recess 56 is, for example, 1.0 to 3.0 mm, preferably 1.5 to 2.5 mm. The depth d7 corresponds to the distance in the groove width direction (the direction parallel to the tread) from the first groove wall 3a in which the first recess 56 is not provided to the deepest portion of the first recess 56. Needless to say, the height h1 and the depth d7 of the first recess 56 can be applied to the second recess 57.

Hereinafter, other embodiments of the present disclosure will be described. In the drawings showing other embodiments, the elements already described are designated by the same reference numerals as those described above, and the above-described configurations can be applied.

FIG. 13 shows an enlarged view of the first middle land portion 12 of another embodiment. As shown in FIG. 13, the first vertical sipe 33 provided in the first middle land portion 12 extends in a zigzag shape in the tire circumferential direction. The first vertical sipe 33 may be, for example, a smooth curve extending in a wavy shape. The amplitude amount A1 (peak to peak value) in the tire axial direction of the first vertical sipe 33 is, for example, 1.0% to 8.0 of the width W7 in the tire axial direction of the first middle land portion 12. %. Further, the first vertical sipe 33 extends in a zigzag shape so as to have one cycle with respect to the two pitches of the first middle sipe 30. Such a first vertical sipe 33 can also provide a frictional force in the tire circumferential direction.

FIG. 14 shows an enlarged view of the first middle land portion 12 of still another embodiment. As shown in FIG. 14, the first vertical sipe 33 provided in the first middle land portion 12 extends intermittently in the tire circumferential direction. That is, the first vertical sipe 33 is composed of a plurality of vertical sipe pieces 54 arranged in the tire circumferential direction. The tire circumferential length L11 of one vertical sipe piece 54 is, for example, 20% to 60% of the tire circumferential length P2 of the first middle sipe 30. Such a first vertical sipe 33 can provide a frictional force in the tire axial direction while maintaining the rigidity of the first middle land portion 12.

The configuration of the first vertical sipe 33 shown in FIGS. 13 and 14 can also be applied to the second vertical sipe 48 provided in the second middle land portion 14.

FIG. 15 shows a development view of the tread portion 2 of still another embodiment. This embodiment also includes the above-mentioned configuration of the ground plane, and the description thereof is omitted here. FIG. 16 shows an enlarged view of the first middle land portion 12 of the embodiment shown in FIG. As shown in FIG. 16, in the first middle land portion 12 of this embodiment, in addition to the above-mentioned first vertical sipe 33, a plurality of first parts completely crossing the first middle land portion 12 in the tire axial direction. A middle sipe 30 is provided. Such a first middle sipe 30 can provide a large frictional force on a wet road surface while maintaining steering stability.

The one-pitch length P1 in the tire circumferential direction of the plurality of first middle sipes 30 is, for example, 100% to 150% of the width W7 of the ground contact surface of the first middle land portion 12. As a result, steering stability and wet performance can be improved in a well-balanced manner.

The first middle sipe 30 of this embodiment is inclined in the first direction (upward to the right) with respect to the tire axial direction and extends linearly, for example. The angle of the first middle sipe 30 with respect to the tire axial direction is, for example, 30 to 50 °. Such a first middle sipe 30 can also provide a frictional force in the tire axial direction during wet running.

The first middle sipe 30 has, for example, a cross-sectional shape similar to that shown in FIG. That is, the first middle sipe 30 shown in FIG. 16 includes a main body portion 30a and a widening portion 30b that is open at the tread surface of the land portion and has a width larger than that of the main body portion 30a. As a more desirable embodiment, it is desirable that the width of the widened portion 30b of the first middle sipe 30 of this embodiment is continuously increased from the first shoulder circumferential groove 5 to the first crown circumferential groove 6. Such a first middle sipe 30 helps to equalize the contact pressure acting on the tread surface of the first middle land portion 12 and suppress uneven wear.

FIG. 17 shows a sectional view taken along line OH of FIG. As shown in FIG. 17, the first middle sipe 30 includes, for example, a first middle tie bar 34 with a locally raised bottom. The first middle tie bar 34 is arranged in, for example, a central region when the first middle sipe 30 is divided into three equal parts in the tire axial direction. The length L12 in the tire axial direction of the first middle tie bar 34 is 30% to 50% of the width W7 (shown in FIG. 16) of the ground contact surface of the first middle tie bar 34 in the tire axial direction. When the length of the first middle tie bar 34 in the tire axial direction changes in the tire radial direction, the length shall be measured at the center position in the tire radial direction. The depth d9 from the ground plane of the first middle land portion 12 to the outer surface of the first middle tie bar 34 is 50% to 70% of the maximum depth d8 of the first middle sipe 30. Such a first middle tie bar 34 can maintain the rigidity of the first middle land portion 12, and can further improve the steering stability.

As shown in FIG. 16, the first middle land portion 12 of this embodiment is provided with a first vertical sipe 33. The first vertical sipe 33 of this embodiment extends linearly, for example, in parallel with the tire circumferential direction. The opening width of the first vertical sipe 33 is, for example, 0.5 to 2.0 mm, and the depth is 1.0 to 4.0 mm. The configuration of the first vertical sipe 33 described above can be applied to the first vertical sipe 33. Therefore, the configuration of the first vertical sipes 33 already described may be applied to the embodiments shown in FIGS. 15 and 16.

Therefore, a plurality of first vertical sipes 33 intermittently extending in the tire circumferential direction may be provided and applied to the first middle land portion 12 of this embodiment (not shown). In this case, it is desirable that the plurality of first vertical sipes 33 are arranged without communicating with the first middle sipes 30. In other words, the first middle sipe 30 does not intersect the first vertical sipe 33, and both ends of the first middle sipe 30 in the tire circumferential direction are interrupted in the block between the two first middle sipe 30s. desirable. Further, in this case, it is desirable that the length of one first vertical sipe 33 in the tire circumferential direction is 70% or more of the one-pitch length P1 of the first middle sipe 30. In such an embodiment, since the first middle sipe 30 and the first vertical sipe 33 do not communicate with each other, uneven wear of the first middle land portion 12 can be suppressed.

FIG. 18 shows a modified example of the first vertical sipe 33 in the embodiment of FIG. As shown in FIG. 18, the first vertical sipe 33 oscillates in the tire axial direction and extends in a wavy shape. It is desirable that the first vertical sipe 33 extends in a sinusoidal shape, for example. The amplitude amount A2 (peak to peak value) of the first vertical sipe 33 in the tire axial direction is, for example, 1.0% to 8% of the width W7 of the tread of the first middle land portion 12 in the tire axial direction. It is 0.0%. Further, the wavelength L13 of the first longitudinal sipe 33 is 150% to 250%, preferably 180% to 220% of the one-pitch length P1 of the first middle sipe 30. Such a first vertical sipe 33 can improve wet performance while maintaining the rigidity of the first middle land portion 12.

As shown in FIG. 15, the second middle sipe 14 of this embodiment is provided with a plurality of second middle sipe 45 similar to the first middle sipe 30 described above. That is, the second middle sipe 45 is inclined in the same direction as the first middle sipe 30 with respect to the tire axial direction. Such a second middle sipe 45 can enhance steering stability and wet performance in cooperation with the first middle sipe 30. Further, the second middle land portion 14 is provided with a second vertical sipe 48 similar to the first vertical sipe 33. The configuration of the first vertical sipe 33 described above can be applied to the second vertical sipe 48.

Further, the crown land portion 13 of this embodiment is provided with a plurality of crown sipes 40 inclined in the same direction as the first middle sipes with respect to the tire axial direction. Further, in these crown sipes 40, the width of the widened portion becomes smaller toward the tire equator C side. Such a crown sipe 40 can secure a large contact area in the vicinity of the tire equator C of the crown land portion 13 and enhance excellent steering stability. In addition, various configurations already described can be applied to the crown sipe 40 of the embodiment of FIG.

The first shoulder sipe 21 provided on the first shoulder land portion 11 of this embodiment is connected to an inclined portion 26 extending inclined from the first shoulder circumferential groove 5 in the tire axial direction and the inclined portion 26. Moreover, it includes an axial portion 27 extending along the tire axial direction. A similar sipe is provided on the land portion 15 of the second shoulder. Such sipes can also provide frictional forces in the tire axial direction on wet road surfaces.

Further, the first shoulder land portion 11 is provided with a break sipe 28 that extends from the first shoulder circumferential groove 5 and is interrupted without reaching the first tread end T1. Such a interrupted sipe 28 can improve the wet performance while maintaining the rigidity of the first shoulder land portion 11.

Although the tire of one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the specific embodiment described above, and may be changed to various embodiments.

A tire of size 235 / 55R19 having the basic pattern of FIG. 1 was prototyped based on the specifications of Tables 1 to 3. Further, as a reference tire (reference tire) for comparing noise performance, a tire having a pattern shown in FIG. 19 was prototyped.

Each land portion of this reference tire is arranged with the widening portion removed from the sipes shown in FIG. Further, in the reference tire, the width Wa of the first shoulder land portion a and the width We of the second shoulder land portion e are the same. Further, the width Wb of the first middle land portion b, the width Wc of the crown land portion c, and the width Wd of the second middle land portion d are the same. Further, the widths Wa and We are larger than the widths Wc, Wd and We. As a result, the reference tire has the tire axial direction of the first shoulder land portion a, the first middle land portion b, the crown land portion c, the second middle land portion d, and the second shoulder land portion e under a 50% load load condition. When the widths of the ground planes of the above are W1s, W1m, Wc, W2m and W2s, respectively, the following equation (5) is satisfied. Further, the width Wco of the outer ground contact surface and the width Wci of the inner ground contact surface of the crown land portion c are the same.
W1s = W2s> W1m = Wc = W2m ... (5)

Further, as a comparative example, a tire having the pattern shown in FIG. 20 was prototyped. In the tire of the comparative example, the distribution of the width of the land portion is the same as that of the reference tire, and the widening portion is provided in each sipe as in FIG. The tires of the comparative examples are substantially the same as those shown in FIG. 1, except for the above items. The steering stability and noise performance of each test tire on dry roads were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 19 x 7.0J
Tire internal pressure: 230kPa
Test vehicle: Displacement 2000cc, four-wheel drive vehicle Tire mounting position: All wheels

<Maneuvering stability on dry roads>
The steering stability on a dry road surface when the test vehicle was driven on a general road was evaluated by the driver's sensuality. The result is a score with the steering stability of the comparative example as 100, and the larger the value, the better the steering stability on the dry road surface.

<Noise performance>
The test vehicle traveled on a dry road surface at 40 to 100 km / h, and the maximum sound pressure of noise in the vehicle at this time was measured. The result is shown by an index in which the sound pressure reduction amount, which is the difference from the sound pressure of the reference tire, is set to 100 in the comparative example. The larger this index is, the smaller the maximum sound pressure of the noise is, and the better the noise performance is exhibited.
The test results are shown in Tables 1-3.

As a result of the test, it was confirmed that the tire of the example had improved steering stability on a dry road surface. It was also confirmed that the tires of the examples had improved noise performance.

[Additional Notes]
The disclosure includes the following aspects:

[Disclosure 1]
A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion is formed in the tire circumferential direction between the first tread end that is outside the vehicle when mounted on the vehicle, the second tread end that is inside the vehicle when mounted on the vehicle, and the first tread end and the second tread end. It includes a plurality of continuously extending circumferential grooves and a plurality of land portions divided into the circumferential grooves.
The plurality of land portions include a crown land portion arranged on the tire equatorial line, a first middle land portion adjacent to the first tread end side of the crown land portion, and a second tread end side of the crown land portion. Including the second middle land area adjacent to
In a 50% load load state where the rim is assembled to the regular rim with the regular internal pressure and 50% of the regular load is applied and the camber angle is 0 ° and the contact patch is grounded on a flat surface, the first middle land portion and the crown land. When the widths of the ground contact surface in the tire axial direction of the second middle land portion are W1m, Wc, and W2m, respectively, the following equation (1) is satisfied.
The crown land portion includes an outer contact patch on the first tread end side of the tire equator and an inner contact patch on the second tread end side of the tire equator.
When the widths of the outer contact patch and the inner contact patch in the tire axial direction are Wco and Wci, respectively, the following equation (2) is satisfied.
tire.
W1m>Wc> W2m ... (1)
Wco> Wci ... (2)
[Disclosure 2]
The tire according to any one of the present disclosure 1, wherein the width of the outer contact patch in the tire axial direction is 51% to 55% of the width of the contact patch of the crown land portion in the tire axial direction.
[Disclosure 3]
The tire according to the present disclosure 1 or 2, wherein the first middle land portion is provided with a first vertical sipe extending in the tire circumferential direction.
[Disclosure 4]
The tire according to the present disclosure 3, wherein the first vertical sipe extends continuously in the tire circumferential direction.
[Disclosure 5]
The tire according to the present disclosure 4, wherein the first vertical sipe extends in a zigzag shape.
[Disclosure 6]
The tire according to the present disclosure 3, wherein the first vertical sipe extends intermittently in the tire circumferential direction.
[Disclosure 7]
The first middle land portion is a tread between the first vertical edge on the end side of the first tread, the second vertical edge on the end side of the second tread, and the first vertical edge and the second vertical edge. Including and
The first middle land portion communicates with the first vertical edge and has a break in the first middle land portion, and the outer first middle sipe communicates with the second vertical edge and enters the first middle land portion. The tire according to any one of the present disclosures 1 to 6, which is provided with an inner first middle sipe having a break in the tire.
[Disclosure 8]
The tire according to the present disclosure 7, wherein the length of the outer first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction.
[Disclosure 9]
The tire according to the present disclosure 7 or 8, wherein the length of the inner first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction.
[Disclosure 10]
The tire according to any one of the present disclosures 1 to 6, wherein the first middle land portion is provided with a plurality of first middle sipes that completely cross the first middle land portion in the tire axial direction.
[Disclosure 11]
The first middle sipe is inclined with respect to the tire axial direction and
The tire according to the present disclosure 10, wherein the second middle land portion is provided with a plurality of second middle sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction.
[Disclosure 12]
The first middle sipe is inclined with respect to the tire axial direction and
The tire according to the present disclosure 10 or 11, wherein the crown land portion is provided with a plurality of crown sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction.
[Disclosure 13]
The circumferential groove includes a first groove wall and a second groove wall facing each other.
The first groove wall is provided with a plurality of first recesses recessed outward in the groove width direction from the groove edge of the circumferential groove in which the tread surface of the tread portion appears.
The second groove wall is provided with a plurality of second recesses recessed outward in the groove width direction from the groove edge of the circumferential groove in which the tread surface of the tread portion appears.
In the first recess and the second recess, the amount of recess from the groove edge gradually decreases from the deepest portion recessed outward in the groove width direction to both sides in the tire circumferential direction.
A plurality of sipes communicating with the circumferential groove are provided in the tire circumferential direction in the land portion adjacent to the circumferential groove.
One of the present disclosures 1 to 12, wherein the first recess and the second recess are provided one by one between the length of 1.0 to 3.0 times the length of one pitch of the sipe. The tires listed.

2 Tread part 3 Circumferential groove 4 Land part 12 1st middle land part 13 Crown land part 14 2nd middle land part 36 Outer contact patch 37 Inner contact patch T1 1st tread end T2 2nd tread end

Claims (13)

A tire with a tread that is oriented to be mounted on a vehicle.
The tread portion is formed in the tire circumferential direction between the first tread end that is outside the vehicle when mounted on the vehicle, the second tread end that is inside the vehicle when mounted on the vehicle, and the first tread end and the second tread end. It includes a plurality of continuously extending circumferential grooves and a plurality of land portions divided into the circumferential grooves.
The plurality of land portions include a crown land portion arranged on the tire equatorial line, a first middle land portion adjacent to the first tread end side of the crown land portion, and a second tread end side of the crown land portion. Including the second middle land area adjacent to
In a 50% load load state where the rim is assembled to the regular rim with the regular internal pressure and 50% of the regular load is applied and the camber angle is 0 ° and the contact patch is grounded on a flat surface, the first middle land portion and the crown land. When the widths of the ground contact surface in the tire axial direction of the second middle land portion are W1m, Wc, and W2m, respectively, the following equation (1) is satisfied.
The crown land portion includes an outer contact patch on the first tread end side of the tire equator and an inner contact patch on the second tread end side of the tire equator.
When the widths of the outer contact patch and the inner contact patch in the tire axial direction are Wco and Wci, respectively, the following equation (2) is satisfied.
tire.
W1m>Wc> W2m ... (1)
Wco> Wci ... (2) The tire according to any one of claims 1, wherein the width of the outer contact patch in the tire axial direction is 51% to 55% of the width of the contact patch of the crown land portion in the tire axial direction. The tire according to claim 1 or 2, wherein the first middle land portion is provided with a first vertical sipe extending in the tire circumferential direction. The tire according to claim 3, wherein the first vertical sipe extends continuously in the tire circumferential direction. The tire according to claim 4, wherein the first vertical sipe extends in a zigzag shape. The tire according to claim 3, wherein the first vertical sipe extends intermittently in the tire circumferential direction. The first middle land portion is a tread between the first vertical edge on the end side of the first tread, the second vertical edge on the end side of the second tread, and the first vertical edge and the second vertical edge. Including and
The first middle land portion communicates with the first vertical edge and has a break in the first middle land portion, and the outer first middle sipe communicates with the second vertical edge and enters the first middle land portion. The tire according to any one of claims 1 to 6, which is provided with an inner first middle sipe having a break in the tire. The tire according to claim 7, wherein the length of the outer first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction. The tire according to claim 7 or 8, wherein the length of the inner first middle sipe in the tire axial direction is 20% to 45% of the width of the first middle land portion in the tire axial direction. The tire according to any one of claims 1 to 6, wherein the first middle land portion is provided with a plurality of first middle sipes that completely cross the first middle land portion in the tire axial direction. The first middle sipe is inclined with respect to the tire axial direction and
The tire according to claim 10, wherein the second middle land portion is provided with a plurality of second middle sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction. The first middle sipe is inclined with respect to the tire axial direction and
The tire according to claim 10 or 11, wherein the crown land portion is provided with a plurality of crown sipes inclined in the same direction as the first middle sipes with respect to the tire axial direction. The circumferential groove includes a first groove wall and a second groove wall facing each other.
The first groove wall is provided with a plurality of first recesses recessed outward in the groove width direction from the groove edge of the circumferential groove in which the tread surface of the tread portion appears.
The second groove wall is provided with a plurality of second recesses recessed outward in the groove width direction from the groove edge of the circumferential groove in which the tread surface of the tread portion appears.
In the first recess and the second recess, the amount of recess from the groove edge gradually decreases from the deepest portion recessed outward in the groove width direction toward both sides in the tire circumferential direction.
A plurality of sipes communicating with the circumferential groove are provided in the tire circumferential direction in the land portion adjacent to the circumferential groove.
One of claims 1 to 12, wherein the first recess and the second recess are provided between 1.0 to 3.0 times the length of one pitch of the sipe. Tires listed in section.

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