JP7287519B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire, and more particularly to a tire that can be suitably implemented as an all-season tire.

All-season tires require basic driving performance not only on dry roads but also on snowy roads. In order to improve on-snow performance, it is effective to provide a large number of lateral grooves in the tread portion. The lateral grooves generate traction on the snow (snow column shear force) by compacting and shearing the snow on the road surface within the grooves. In addition, the edges of the lateral grooves generate frictional force by scratching the compacted snow road. As a related technique, there is Patent Document 1 below.

JP 2015-013604 A

The lateral grooves provided in the tread help improve traction on snow, but they are not sufficient for improving turning performance on snow, and further improvements are required. In addition, the lateral grooves tend to reduce the pattern rigidity of the tread portion, which in turn deteriorates the steering stability on dry road surfaces.

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems described above, and a main object of the present invention is to provide a tire capable of exhibiting excellent on-snow performance over a long period of time .

The present invention is a tire having a tread portion, the tread portion including a land portion having a tread surface divided by a first longitudinal edge extending in the tire circumferential direction and a second longitudinal edge extending in the tire circumferential direction. , the land portion is disposed between the tire equator and the tread edge, the land portion is provided with a lateral groove extending from the first longitudinal edge to the second longitudinal edge, the lateral groove extending from the first longitudinal edge; It includes a first portion extending from an edge, a second portion extending from the second longitudinal edge, and a connecting portion connecting them, the connecting portion being a first small edge projecting from the first portion in the tire circumferential direction. and a second small edge projecting in the tire circumferential direction on the side opposite to the first small edge from the second portion, and the connecting portion is located at the center position of the land portion in the axial direction of the tire. is located closer to the tread end side than the

In the tire of the present invention, the land portion is provided with a short groove that extends from the second longitudinal edge and is discontinued within the land portion, and the short groove extends from the end on the second longitudinal edge side to the inside of the land portion. It is desirable that the depth gradually decreases towards the discontinuity of the .

In the tire of the present invention, the land portion is provided with a sipe extending from the first longitudinal edge to the second longitudinal edge, and the sipe has a body portion and a depth smaller than that of the body portion. It is desirable to include a shallow portion .

In the tire of the present invention, it is preferable that the land portions are provided with a plurality of types of sipes having different positions of the shallow portion in the axial direction of the tire .

The tread portion of the tire of the present invention includes a land portion having a tread surface divided by a first longitudinal edge extending in the tire circumferential direction and a second longitudinal edge extending in the tire circumferential direction. The land portion is arranged between the tire equator and the tread edge. The land portion is provided with a lateral groove extending from the first longitudinal edge to the second longitudinal edge. The lateral groove includes a first portion extending from a first longitudinal edge, a second portion extending from a second longitudinal edge, and a connecting portion connecting them. The connecting portion is a portion between a first small edge projecting from the first portion in the tire circumferential direction and a second small edge projecting from the second portion in the tire circumferential direction opposite to the first small edge. .

A lateral groove including such a connecting portion not only enhances on-snow traction, but also provides a frictional force in the axial direction of the tire by means of the first and second small edges, thereby enhancing turning performance on snow.

In the present invention, the connecting portion is positioned closer to the tread end than the center position of the middle land portion in the tire axial direction.

As a result, snow is easily discharged from the connecting portion due to changes in ground contact pressure when traveling on snow, and excellent on-snow performance is exhibited over a long period of time.

As described above, the tire of the present invention can exhibit excellent on-snow performance over a long period of time .

1 is a developed view of a tread portion of a pneumatic tire according to one embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the middle land portion of FIG. 1; 3 is an enlarged view of the lateral groove of FIG. 2; FIG. 2. (A) is a sectional view taken along line AA of FIG. 2, and (B) is a sectional view taken along line BB of FIG. 2. (A) is a sectional view taken along line CC of FIG. 2, and (B) is a sectional view taken along line DD of FIG. FIG. 2 is an enlarged view of a shoulder land portion in FIG. 1; FIG. 2 is an enlarged view of the crown land portion of FIG. 1; FIG. 4 is an enlarged view of a middle land portion of a tire of a comparative example;

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. The tire 1 of this embodiment is configured as, for example, a pneumatic tire. In this embodiment, an all-season tire intended for installation on passenger cars and SUVs is shown as a preferred embodiment. The tread portion 2 of the tire 1 of the present embodiment is not specified in the mounting direction to the vehicle, and has a point-symmetrical pattern with respect to a point on the tire equator C, for example. However, the present invention is not limited to such an aspect.

As shown in FIG. 1, the tread portion 2 is provided with a plurality of main grooves 3 continuously extending in the tire circumferential direction. The main grooves 3 include, for example, shoulder main grooves 4 arranged on the tread edge Te side, and crown main grooves 5 arranged on the tire equator C side of the shoulder main grooves 4 .

In the case of a pneumatic tire, the tread edge Te is applied to a tire 1 in a normal state, which is mounted on a normal rim and filled with a normal internal pressure, and is in a normal state. This is the outermost contact point in the axial direction of the tire. Unless otherwise specified, the dimensions of each part of the tire are values measured under normal conditions.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. Then 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".

Two shoulder main grooves 4 are provided in the tread portion 2 of the present embodiment. The axial distance L1 from the groove center line of each shoulder main groove 4 to the tire equator C is, for example, 0.20 to 0.30 times the tread width TW. The tread width TW is the distance in the tire axial direction from one tread end Te to the other tread end Te in the normal state.

The crown main groove 5 of this embodiment is provided between the shoulder main groove 4 and the tire equator C, for example. Two crown main grooves 5 sandwiching the tire equator C are provided in the tread portion 2 of the present embodiment. A distance L2 from the groove centerline of the crown main groove 5 to the tire equator C is, for example, 0.05 to 0.15 times the tread width TW. However, the present invention is not limited to such an aspect, and one crown main groove 5 may be provided on the tire equator C in another aspect.

Each main groove 3 extends linearly, for example. Each main groove 3 may extend, for example, in a zigzag shape. The groove width W1 of the main groove 3 is preferably, for example, 4.0% to 6.0% of the tread width TW. The groove depth of the main groove 3 is preferably 5.0 to 12.0 mm, for example. As a result, steering stability on dry road surfaces and performance on snow are improved in a well-balanced manner.

The tread portion 2 is divided into a plurality of land portions by the main grooves 3 described above. The tread portion 2 of this embodiment is divided into a crown land portion 6 , two middle land portions 7 and two shoulder land portions 8 . The crown land portion 6 is divided between the two crown main grooves 5 and provided on the tire equator C. As shown in FIG. The middle land portion 7 is divided between the crown main groove 5 and the shoulder main groove 4 . The shoulder land portion 8 is divided between the shoulder main groove 4 and the tread edge Te. Thus, the tread portion 2 of this embodiment is composed of five land portions. However, in another aspect, the tread portion 2 may be divided into four land portions by, for example, two shoulder main grooves 4 and one crown main groove 5 .

FIG. 2 shows an enlarged view of the middle land portion 7 as a diagram showing one aspect of the land portion. As shown in FIG. 2, the middle land portion 7 has a tread surface divided by a first longitudinal edge 7a extending in the tire circumferential direction and a second longitudinal edge 7b extending in the tire circumferential direction. In this embodiment, the first longitudinal edge 7a is the edge on the tire equator C side. The second vertical edge 7b is an edge on the tread edge Te side.

The middle land portion 7 is provided with a plurality of lateral grooves 10 extending from the first longitudinal edge 7a to the second longitudinal edge 7b in the tire circumferential direction.

The lateral groove 10 includes a first portion 11 extending from the first longitudinal edge 7a, a second portion 12 extending from the second longitudinal edge 7b, and a connecting portion 13 connecting them.

The groove width W2 of the first portion 11 is, for example, 0.20 to 0.40 times the groove width W1 of the main groove 3 (shown in FIG. 1). The groove width of the second portion 12 is also the same. The first portion 11 and the second portion 12 are, for example, inclined in the same direction with respect to the tire axial direction. The angle of the groove edges of the first portion 11 and the second portion 12 with respect to the axial direction of the tire is, for example, 25 to 35°. Further, the first portion 11 and the second portion 12 are, for example, connected to each other while being displaced in the tire circumferential direction. The positional deviation amount between the first portion 11 and the second portion 12 in the tire circumferential direction is, for example, 0.50 to 0.60 times the groove width of the first portion 11 or the second portion 12 .

An enlarged view of the lateral groove 10 is shown in FIG. As shown in FIG. 3 , the connecting portion 13 includes a first small edge 16 protruding from the first portion 11 in the tire circumferential direction and a second portion 12 extending from the second portion 12 in the tire circumferential direction opposite to the first small edge 16 . It is the portion between the protruding second small edge 17 . The angle of the first small edge 16 and the second small edge 17 with respect to the tire circumferential direction is, for example, 0 to 10 degrees. Since the lateral groove 10 has the connecting portion 13 , each of the pair of edges of the lateral groove 10 is bent in an S shape at the connecting portion 13 .

The lateral grooves including the connecting portion 13 not only improve the traction on snow, but also provide frictional force in the axial direction of the tire by means of the first small edge 16 and the second small edge, thereby improving turning performance on snow. can.

The lengths of the first small edge 16 and the second small edge 17 in the tire circumferential direction are smaller than the maximum groove width of the first portion 11 and the maximum groove width of the second portion 12 . This suppresses a decrease in the rigidity of the land portion due to the connection portion 13 .

The connecting portion 13 has, at least in part, a raised bottom portion 18 having a depth smaller than the depth of the lateral groove 10 at the first longitudinal edge 7a and the depth of the second longitudinal edge 7b.

The connecting portion 13 tends to be a relatively large groove space, but at least part of it has a raised depth that is less than the depth at the first longitudinal edge 7a and the depth at the second longitudinal edge 7b of the transverse groove 10. The presence of the bottom portion 18 suppresses a local decrease in rigidity of the tread portion 2, thereby improving steering stability on a dry road surface. It should be noted that in FIG. 3 the raised bottom 18 and the area having the same depth as the raised bottom 18 are colored to facilitate understanding of the invention.

FIG. 4(A) shows a cross-sectional view of the lateral groove 10 of FIG. 2 taken along the line AA. As shown in FIG. 4 , in this embodiment, a raised bottom portion 18 is formed over the entire connecting portion 13 . In a further preferred embodiment, the first portion 11 has, at least in part, the same depth as the raised bottom portion 18 . Such lateral grooves 10 can further improve steering stability on dry road surfaces.

The depth d1 at the first longitudinal edge 7a and the depth d2 at the second longitudinal edge 7b of the lateral groove 10 are 0.65 to 0.75 times the depth of the main groove 3, respectively. The depth d3 of the raised bottom portion 18 is 0.40 to 0.50 times the depth of the main groove 3, for example. Also, the depth d3 of the raised bottom portion 18 is preferably 0.60 to 0.75 times the depth d1 of the lateral groove 10 .

As shown in FIG. 3, it is desirable that the connecting portion 13 be located closer to the tread edge Te than the center position of the middle land portion 7 in the tire axial direction. More specifically, both the first small edge 16 and the second small edge 17 are located closer to the tread edge Te than the center position. As a result, snow is easily discharged from the connecting portion 13 due to changes in the contact pressure when traveling on snow, and excellent on-snow performance is exhibited over a long period of time.

The groove edge of the first portion 11 and the first small edge 16 are connected by, for example, an arc portion that protrudes inward of the groove. The groove edge of the second portion 12 and the second small edge 17 are connected by, for example, an arc portion that protrudes inward of the groove.

Similarly, the first small edge 16 and the groove edge of the second portion 12 are connected by, for example, an arc portion 16a projecting outward from the groove. As a result, uneven wear of the groove edge of the connecting portion 13 is suppressed. The first partial length L3 corresponding to the distance in the tire axial direction from the first vertical edge 7a to the end of the circular arc portion 16a is, for example, the axial width W3 of the middle land portion 7 (shown in FIG. 2, The same applies hereinafter.) is 0.50 to 0.65 times.

The second small edge 17 and the groove edge of the first portion 11 are connected by an arc portion 17a projecting outward from the groove. A distance L4 in the tire axial direction from the first vertical edge 7a to the circular arc portion 17a is, for example, 0.60 to 0.80 times the width W3 of the middle land portion 7 in the tire axial direction.

A width W4 of the connecting portion 13 in the axial direction of the tire (shown in FIG. 2 and the same applies hereinafter) is larger than, for example, the maximum groove width of the first portion 11 and the maximum groove width of the second portion 12. is desirable. The axial width W4 of the connecting portion 13 is defined as the axial distance from the longitudinal center position of the first small edge 16 to the longitudinal center position of the second small edge 17 . In a more desirable mode, the width W4 of the connecting portion 13 is 0.10 to 0.25 times the width W3 of the middle land portion 7, for example. Such a connecting portion 13 can improve steering stability on a dry road surface and performance on snow in a well-balanced manner.

A width W5 of the connecting portion 13 in the tire circumferential direction (shown in FIG. 2 and the same applies hereinafter) is, for example, greater than a width W4 of the connecting portion 13 in the tire axial direction. The width of the connecting portion 13 in the tire circumferential direction is the width of the groove between the second small edge 17 and the first portion 11 from the end in the tire circumferential direction of the arc portion where the first small edge 16 and the groove edge of the second portion 12 are connected. It is defined by the tire circumferential distance to the tire circumferential end of the arc portion connected to the edge. In a more desirable aspect, the width W5 of the connecting portion 13 in the tire circumferential direction is 1.3 to 2.0 times the width W4 of the connecting portion 13 in the tire axial direction.

As shown in FIG. 2 , the middle land portion 7 of this embodiment is provided with, for example, a plurality of short grooves 20 and a plurality of sipes 21 . In this specification, a "sipe" is a cut with a width of less than 1.5 mm. More preferably, the width of the sipe is 0.5-1.0 mm.

The length L5 of the short groove 20 in the axial direction of the tire is, for example, 0.40 to 0.55 times the width W3 of the middle land portion 7 in the axial direction of the tire. In a desirable aspect, the short groove 20 is discontinued on the second vertical edge 7b side of the center position of the land portion in the axial direction of the tire. Such short grooves 20 can improve on-snow performance while maintaining the rigidity of the middle land portion 7 .

The groove width W6 of the short groove 20 is preferably smaller than, for example, the axial width W4 and the circumferential width W5 of the connecting portion 13 . Such short grooves 20 can further enhance steering stability on dry road surfaces.

FIG. 4B shows a cross-sectional view of the short groove 20 taken along line BB. As shown in FIG. 4B, it is desirable that the depth of the short groove 20 gradually decreases from the end on the side of the second vertical edge 7b toward the discontinuous end in the middle land portion 7. As shown in FIG. In a more desirable embodiment, a variable depth portion 20b having an inclined groove bottom and varying depth is provided between two constant depth portions 20a extending at a constant depth. Such a short groove 20 facilitates discharging the snow inside due to the deformation of the land portion when driving on snow.

As shown in FIG. 2, the sipe 21 is provided between the lateral groove 10 and the short groove 20, for example. The sipe 21 extends, for example, from the first longitudinal edge 7a to the second longitudinal edge 7b. The sipe 21 of this embodiment is preferably inclined in the same direction as the first portion 11 and the second portion 12 of the lateral groove 10 with respect to the tire axial direction. The angle of the sipe 21 with respect to the tire axial direction is, for example, 20 to 30 degrees.

The sipe 21 is provided with, for example, a first sipe 22 and a second sipe 23 having different depth distributions. FIG. 5(A) shows a cross-sectional view of the first sipe 22 taken along line CC. FIG. 5B shows a cross-sectional view of the second sipe 23 taken along line DD. As shown in FIGS. 5A and 5B, the sipe 21 preferably includes a body portion 21a and a shallow portion 21b having a depth smaller than that of the body portion 21a. The depth d2 of the main body portion 21a is 0.65 to 0.75 times the depth of the main groove 3, for example. The depth d3 of the shallow bottom portion 21b is 0.40 to 0.50 times the depth d1 of the main groove 3, for example. The shallow bottom portion 21b can prevent the sipe 21 from opening excessively, improve steering stability on a dry road surface, and prevent uneven wear of the middle land portion 7. As shown in FIG.

The middle land portion 7 of the present embodiment is provided with a plurality of types of sipes 21 having shallow bottom portions 21b at different positions in the axial direction of the tire. Specifically, the first sipe 22 has, for example, a shallow bottom portion 21b on the side of the first vertical edge 7a. The second sipe 23 has, for example, a shallow bottom portion 21b on the side of the second vertical edge 7b. Thereby, uneven wear of the middle land portion 7 is further suppressed.

FIG. 6 shows an enlarged view of the shoulder land portion 8. As shown in FIG. As shown in FIG. 6 , the shoulder land portion 8 is provided with a plurality of shoulder lateral grooves 25 , shoulder sipes 29 and chamfers 28 .

The shoulder lateral grooves 25 include, for example, first shoulder lateral grooves 26 extending from the tread edge Te to the shoulder main groove 4 and second shoulder lateral grooves 27 extending from the tread edge Te and discontinuing within the shoulder land portion 8 .

As shown in FIG. 1, it is desirable that the end portion of the first shoulder lateral groove 26 on the side of the shoulder main groove 4 intersects a region extending the short groove 20 of the middle land portion 7 in its longitudinal direction. Note that "extending the groove in the length direction" means extending the groove while maintaining the radius of curvature at the end of the groove. As a result, when running on snow, the shoulder main groove 4, the short grooves 20 and the first shoulder lateral grooves 26 cooperate to form a large snow column and provide a large snow column shearing force.

It is desirable that the end portion of the second shoulder lateral groove 27 on the side of the shoulder main groove 4 intersects a region obtained by extending the second portion of the lateral groove 10 of the middle land portion 7 in its longitudinal direction. As a result, the lateral grooves 10 can be prevented from opening excessively, further improving the steering stability on dry road surfaces.

As shown in FIG. 6, the shoulder sipe 29 extends from the tread edge Te to the shoulder main groove 4, for example. A plurality of shoulder sipes 29 are provided, for example, between the first shoulder lateral groove 26 and the second shoulder lateral groove 27 . In this embodiment, two shoulder sipes 29 are provided between the first shoulder lateral groove 26 and the second shoulder lateral groove 27 . Such shoulder sipes 29 can provide frictional force on snow.

The chamfered portion 28 is formed by recessing a corner portion between the tread surface and the side surface of the shoulder land portion 8 . The chamfered portion 28 of this embodiment is provided, for example, at a position away from the shoulder lateral groove 25 . It is desirable that the length of the chamfered portion 28 in the tire circumferential direction is, for example, greater than the groove width of the shoulder lateral groove 25 . In a more desirable aspect, the length of the chamfered portion 28 in the tire circumferential direction is greater than the width W5 (shown in FIG. 2) of the connecting portion 13 of the lateral groove 10 in the tire circumferential direction. Such a chamfered portion 28 can suppress clogging of the shoulder main groove 4 with snow while suppressing uneven wear of the shoulder land portion 8 .

The chamfered portion 28 of this embodiment is arranged so as to communicate with the two shoulder sipes 29 . More specifically, shoulder sipes 29 communicate with both ends of the chamfered portion 28 in the tire circumferential direction. Such an arrangement of chamfers 28 serves to further enhance the above effects.

As shown in FIG. 1 , in a more desirable embodiment, the axially extended region of the chamfered portion 28 intersects the end of the sipe 21 arranged in the middle land portion 7 . Such a chamfered portion 28 can suppress clogging of the shoulder main groove 4 with snow while suppressing uneven wear of the shoulder land portion 8 .

An enlarged view of the crown land portion 6 is shown in FIG. As shown in FIG. 7 , the crown land portion 6 is provided with a plurality of crown lateral grooves 30 and a plurality of crown sipes 35 .

The crown lateral grooves 30 , for example, extend from the crown main grooves 5 and are interrupted within the crown land portion 6 . For example, the crown lateral groove 30 of the present embodiment is interrupted without reaching the center position of the crown land portion 6 in the tire axial direction. The axial length L6 of the crown lateral groove 30 is preferably smaller than the axial length L5 (shown in FIG. 2) of the short groove 20 provided in the middle land portion 7 . Specifically, the length L6 of the crown lateral groove 30 in the tire axial direction is preferably 0.20 to 0.30 times the width W7 of the crown land portion 6 in the tire axial direction. Such crown lateral grooves 30 can improve steering stability on dry road surfaces and performance on snow in a well-balanced manner.

The crown land portion 6 of the present embodiment is provided with first crown lateral grooves 31 extending from the crown main groove 5 on one side and second crown lateral grooves 32 extending from the crown main groove 5 on the other side.

The first crown lateral groove 31 and the second crown lateral groove 32 are arranged relatively close to each other. In the present embodiment, a region obtained by extending the first crown lateral groove 31 in its longitudinal direction intersects the second crown lateral groove 32 . This increases traction on snow.

The crown lateral grooves 30 are, for example, inclined with respect to the tire axial direction. In a preferred embodiment, it is inclined in the same direction as the first portion 11 (shown in FIG. 2) of the lateral groove 10 of the middle land portion 7 with respect to the tire axial direction.

As shown in FIG. 1, the end portion of the crown main groove 5 side of the crown lateral groove 30 of the present embodiment intersects with the longitudinally extending region of the first portion 11 of the lateral groove 10 of the middle land portion 7 . As a result, the crown main grooves 5, the lateral grooves 10, and the crown lateral grooves 30 cooperate to form a large snow column during running on snow, thereby exhibiting excellent performance on snow.

As shown in FIG. 7, the crown sipe 35 includes, for example, a first crown sipe 36, a second crown sipe 37, and a third crown sipe 38. As shown in FIG. Each crown sipe 35 is, for example, inclined in the same direction as the lateral groove 10 of the middle land portion 7 with respect to the tire axial direction.

The first crown sipe 36 traverses the crown land portion 6, for example. The first crown sipe 36 of this embodiment has, for example, two gently sloping portions 36a and a steeply sloping portion 36b therebetween. Each gently sloping portion 36a continues to the crown main groove 5 on one side or the other side and extends obliquely with respect to the tire axial direction. The steeply inclined portion 36b is arranged at a larger angle than the gentlely inclined portion 36a with respect to the axial direction of the tire. In a desirable aspect, the steep slope portion 36b extends along the tire circumferential direction. Such a first crown sipe 36 can enhance turning performance on snow.

The second crown sipe 37 extends, for example, from the discontinuous end of the first crown lateral groove 31 to the discontinuous end of the second crown lateral groove 32 . Such a second crown sipe 37 serves to enhance on-snow traction.

The third crown sipe 38 extends, for example, from the crown main groove 5 on one side or the other side and is interrupted within the crown land portion 6 . The third crown sipe 38 of the present embodiment is interrupted without reaching, for example, the center position of the crown land portion 6 in the axial direction of the tire. In a more desirable aspect, the axial length of the third crown sipe 38 is smaller than the axial length of the gently inclined portion 36 a of the first crown sipe 36 .

The third crown sipe 38 preferably intersects, for example, a longitudinally extending region of the gently sloping portion 36a of the first crown sipe 36 . Such a third crown sipe 38, together with the gently sloping portion 36a, helps to increase on-snow traction.

Although the preferred embodiments of the tire of the present invention have been described in detail above, the present invention is not limited to the specific embodiments described above, and can be practiced with various modifications.

A pneumatic tire of size 215/60R16 having the basic pattern shown in FIG. 1 was prototyped. As a comparative example, as shown in FIG. 8, a tire was provided in which a middle land portion a was provided with a middle lateral groove b that did not include a connecting portion. The middle lateral groove b has a flat groove bottom and does not have the raised bottom shown in FIG. 4(A). The tire of the comparative example is substantially the same as the tire shown in FIG. 1 except for the above points. Each test tire was tested for steering stability on a dry road surface and performance on snow. Common specifications and test methods for each test tire are as follows.
Mounting rim: 16 x 7.0J
Tire pressure: 250KPa
Test vehicle: 2500cc displacement, front-wheel drive Tire mounting position: All wheels

<Driving stability on dry road surface>
The steering stability of the test vehicle was evaluated by the driver's sensory perception when the test vehicle was driven on a dry road surface. The results are scored with the comparative example being 100, and the larger the number, the better the steering stability on a dry road surface.

<Snow Performance>
The performance of the test vehicle on which each test tire was mounted was evaluated by the driver's senses when the test vehicle was driven on a snowy road. The results are scored with the comparative example being 100, and the larger the number, the better the on-snow performance.
Test results are shown in Table 1.

As a result of the test, it was confirmed that the tires of Examples had improved steering stability on dry road surfaces and performance on snow.

2 tread portion 7 land portion 7a first longitudinal edge 7b second longitudinal edge 10 lateral groove 11 first portion 12 second portion 13 connecting portion 16 first small edge 17 second small edge 18 raised bottom portion

Claims (4)

A tire having a tread portion,
The tread portion includes a land portion having a tread surface divided by a first longitudinal edge extending in the tire circumferential direction and a second longitudinal edge extending in the tire circumferential direction,
The land portion is arranged between the tire equator and the tread edge,
The land portion is provided with a lateral groove extending from the first longitudinal edge to the second longitudinal edge,
The lateral groove includes a first portion extending from the first longitudinal edge, a second portion extending from the second longitudinal edge, and a connecting portion connecting them,
The connecting portion is between a first small edge projecting from the first portion in the tire circumferential direction and a second small edge projecting from the second portion in the tire circumferential direction opposite to the first small edge. is part of
The connecting portion is located closer to the tread end side than the center position of the land portion in the tire axial direction ,
The axial width of the connecting portion is greater than the maximum groove width of the first portion and greater than the maximum groove width of the second portion,
tire. The land portion is provided with a short groove extending from the second longitudinal edge and interrupted within the land portion,
2. The tire according to claim 1, wherein the depth of the short groove gradually decreases from the end on the side of the second longitudinal edge toward a discontinuous end in the land portion. The land portion is provided with a sipe extending from the first longitudinal edge to the second longitudinal edge,
3. The tire of claim 1 or 2, wherein the sipe includes a body portion and a shallow portion having a depth smaller than the body portion. The tire according to claim 3, wherein the land portions are provided with a plurality of types of the sipes having different axial positions of the shallow portions.

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