JP6931190B2 - tire - Google Patents

Description

The present invention relates to a tire, and more particularly to a tire suitable for traveling on an icy snow road.

For example, various types of tires have been proposed for driving on a snow-packed road surface or an icy road surface (hereinafter, these road surfaces may be collectively referred to as a "snow-ice road surface"). A narrow slit-shaped sipe is formed on each land portion of this type of tire. Such tires increase the frictional force against the snow and ice road surface by the edge of the sipe.

It is conceivable to increase the number of sipes in order to improve the running performance on the snow and ice road surface (hereinafter, may be simply referred to as "snow and ice road performance"). However, such a method has a problem that the rigidity of the land portion is lowered and the steering stability performance on a dry road surface is deteriorated.

Japanese Unexamined Patent Publication No. 2011-42328

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of improving snow and ice road performance while maintaining steering stability performance on dry roads.

In the present invention, the tread portion includes a shoulder land portion arranged on the most tread end side, a middle land portion arranged adjacent to the inner side of the shoulder land portion in the tire axial direction, and the shoulder land portion and the middle land portion. A vertical narrow groove extending in the tire circumferential direction is provided between the portion and the middle land portion is provided with a plurality of middle sipes having an angle α with respect to the tire axial direction, and the shoulder land portion is provided with a plurality of middle sipes. A book shoulder sipe is provided, and the plurality of shoulder sipe is a tire having an inner inclined portion inclined in the tire axial direction at an angle β larger than the angle α of the middle sipe on the vertical narrow groove side. be.

In the tire according to the present invention, it is desirable that the shoulder land portion is provided with a plurality of shoulder lateral grooves for dividing the shoulder land portion into a plurality of shoulder blocks.

In the tire according to the present invention, the shoulder lateral groove has an inner portion arranged on the vertical narrow groove side, and the absolute difference between the angle of the inner portion with respect to the tire axial direction and the angle β of the inner inclined portion is absolute. The value is preferably 5 degrees or less.

In the tire according to the present invention, it is desirable that the shoulder lateral groove has an outer portion on the outer side in the tire axial direction of the inner portion, and the outer portion is inclined with respect to the inner portion.

The tire according to the present invention has a plurality of middle lateral grooves in the middle land portion that divide the middle land portion into a plurality of middle blocks, and the outer end of the middle lateral groove in the tire axial direction is the shoulder lateral groove. It is desirable that the tire is provided at a position where it does not overlap with the inner end in the tire axial direction in the tire circumferential direction.

In the tire according to the present invention, the middle land portion has a width in the tire axial direction in which the width in the tire axial direction repeatedly increases and decreases in the tire circumferential direction and is larger than the average width in the tire axial direction. It is desirable that the wide portion has a wide portion, and the inner end of the shoulder lateral groove in the tire axial direction communicates with the wide portion.

The tire according to the present invention has a plurality of middle lateral grooves in the middle land portion that divide the middle land portion into a plurality of middle blocks, and the outer end of the middle lateral groove in the tire axial direction is the shoulder block. It is desirable to be located in the central part including the intermediate position in the tire circumferential direction.

In the tire according to the present invention, the middle land portion has a minimum width portion having a minimum width in the tire axial direction, the minimum width portion is not provided with the middle lateral groove, and the shoulder lateral groove is formed. It is desirable that the inner end in the tire axial direction is misaligned.

In the tire according to the present invention, it is desirable that the shoulder sipe has an outer inclined portion on the outer side of the inner inclined portion in the tire axial direction, and the outer inclined portion is inclined with respect to the inner inclined portion.

In the tire according to the present invention, it is desirable that the middle sipe alternately has a first middle sipe and a second middle sipe having a depth larger than that of the first middle sipe in the tire circumferential direction.

Further, in the invention according to claim 11, it is desirable that a middle main groove extending in a zigzag shape continuously in the tire circumferential direction inside the middle land portion in the tire axial direction is provided.

The tire of the present invention is provided with a tread portion having a shoulder land portion, a middle land portion, and a vertical narrow groove extending in the tire circumferential direction between the shoulder land portion and the middle land portion. For example, when a large load is applied such as during turning, the shoulder land portion and the middle land portion can support each other and have apparently high rigidity. Therefore, the tire of the present invention can maintain steering stability performance on a dry road surface.

A plurality of middle sipes are provided in the middle land area. Further, a plurality of shoulder sipes are provided on the shoulder land portion. Each of these sipes can scratch the snow and ice road surface by its edge, and thus improve the snow and ice road performance.

The shoulder sipe has an inner inclined portion that is inclined at an angle larger than the angle of the middle sipe with respect to the tire axial direction on the vertical narrow groove side. The medial slope provides a relatively long tire circumferential edge to enhance turning performance on snow and ice roads. On the other hand, the inner inclined portion tends to reduce the tire axial rigidity of the shoulder land portion, but as described above, by providing the inner inclined portion on the vertical narrow groove side, the shoulder land portion and the middle land portion are vertically aligned even during high load driving. By closing and integrating the narrow grooves, such inconvenience can be prevented.

Therefore, the tire of the present invention improves the snow and ice road performance while maintaining the steering stability performance on a dry road surface.

It is a developed view of the tread part of one Embodiment of this invention. It is an enlarged view of the middle land part and the shoulder land part. It is an enlarged view of the middle land part and the shoulder land part. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is an enlarged view of the land part of the crown.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. In the present embodiment, a pneumatic tire for a passenger car is shown as a preferred embodiment. However, it goes without saying that the present invention can be applied to tires 1 of other categories such as for heavy loads.

As shown in FIG. 1, the tread portion 2 of the present embodiment is provided with a shoulder land portion 3, a middle land portion 4, and a crown land portion 5. The shoulder land portion 3, the middle land portion 4, and the crown land portion 5 of the present embodiment are provided on both sides of the tire equator C, respectively. The shoulder land portion 3 is arranged on the most tread end Te side. The middle land portion 4 is arranged adjacent to the inside of the shoulder land portion 3 in the tire axial direction. The crown land portion 5 is arranged adjacent to the inside of the middle land portion 4 in the tire axial direction.

The "tread end" Te is a normal load in which a normal load is applied to a tire 1 in a normal state, which is a normal rim and is filled with a normal internal pressure and is in a normal state, and is grounded on a flat surface at a camber angle of 0 degrees. It is defined as the ground contact position on the outermost side in the tire axial direction under load conditions. In the normal state, the distance between the tread end Te and Te in the tire axial direction is defined as the tread contact width TW. Unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in a 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 JATMA, "Design Rim" for TRA, and ETRTO. If so, 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 JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT 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. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD" The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 is provided with a main groove 6 that extends continuously in the tire circumferential direction. In the present embodiment, the main groove 6 includes a middle main groove 7 and a crown main groove 8. The middle main groove 7 extends inside the middle land portion 4 in the tire axial direction. In the present embodiment, the middle main groove 7 separates the middle land portion 4 and the crown land portion 5. The crown main groove 8 extends inside the land portion 5 of the crown in the tire axial direction. In the present embodiment, the crown main groove 8 divides a pair of crown land portions 5, 5.

The middle main groove 7 extends in a zigzag shape in the tire circumferential direction, for example. Such a middle main groove 7 provides an edge in the tire axial direction and enhances running stability performance on snow and ice roads.

The crown main groove 8 extends linearly in the tire circumferential direction, for example. Since such a crown main groove 8 maintains high tire circumferential rigidity of the crown land portion 5 near the tire equator C on which a large contact pressure acts, the uneven wear resistance performance is improved. The main groove 6 is not limited to such an aspect.

The groove width W1 of the main groove 6 is preferably 2% to 7% of the tread ground contact width TW, for example. The groove depth D1 (shown in FIG. 4) of the main groove 6 is preferably 6 to 12 mm, for example.

The tread portion 2 is provided with a vertical narrow groove 10 extending in the tire axial direction between the shoulder land portion 3 and the middle land portion 4. In such a vertical groove 10, for example, when a large load is applied such as during turning, the shoulder land portion 3 and the middle land portion 4 can support each other and have apparently high rigidity. Therefore, the tire 1 of the present embodiment can maintain the steering stability performance on a dry road surface.

In the present embodiment, the vertical groove 10 extends linearly. Such a vertical groove 10 can increase the rigidity in the tire circumferential direction on the vertical groove 10 side of the shoulder land portion 3 and the middle land portion 4.

The vertical narrow groove 10 is, for example, a groove-like body having a groove width W2 of 1 to 2 mm. The groove depth D2 (shown in FIG. 4) of the vertical narrow groove 10 is preferably 20% to 60% of the groove depth D1 of the main groove 6, for example.

FIG. 2 is an enlarged view of the shoulder land portion 3 and the middle land portion 4 on the left side of FIG. As shown in FIG. 2, the middle land portion 4 is provided with a plurality of middle sipes 11 having an angle α with respect to the tire axial direction. Such a middle sipe 11 scratches the snow and ice road surface by its edge, and thus improves the snow and ice road performance. A sipe is defined herein as a notch with a width of less than 1 mm.

In the present embodiment, the middle sipe 11 is an open type that connects the middle main groove 7 and the vertical narrow groove 10. The middle sipe 11 is inclined to one side (upward to the left in FIG. 2) with respect to the tire axial direction. Such a middle sipe 11 provides a large edge and greatly improves snow and ice road performance.

The angle α of the middle sipe 11 is not particularly limited, but is preferably larger than, for example, 0 degrees. Since such a middle sipe 11 provides an edge in the tire circumferential direction, it enhances turning performance on snow and ice roads. If the angle α becomes excessively large, the provision of the edge in the tire circumferential direction becomes excessively large, which may deteriorate the straight running stability performance on snow and ice roads. Therefore, the angle α is preferably 5 to 20 degrees.

The middle sipe 11 alternately has a first middle sipe 11a and a second middle sipe 11b having a depth larger than that of the first middle sipe 11a in the tire circumferential direction. Such a middle sipe 11 can improve the snow and ice road performance due to the edge while suppressing a decrease in the rigidity of the middle land portion 4.

Although not particularly limited, the depth of the first middle sipe 11a is preferably 30% to 50% of the groove depth of the middle main groove 7. The depth of the second middle sipe 11b is preferably 70% to 80% of the groove depth of the middle main groove 7.

The middle sipe 11 extends in a zigzag shape in the present embodiment. In such a middle sipe 11, when a load such as during turning is applied, the land portions on both sides of the sipe support each other, so that the rigidity of the middle land portion 4 is apparently maintained high. In the present specification, the angle of the zigzag sipe with respect to the tire axial direction is the angle between the zigzag amplitude center line n and the tire axial direction line. Further, the sipes of the present embodiment are not limited to those extending in a zigzag shape.

Each middle sipe 11 has a tire circumferential pitch P1 having the same size. As a result, the rigidity in the tire circumferential direction between the middle sipes 11 and 11 is made uniform, so that the uneven wear resistance performance is improved.

A plurality of shoulder sipes 13 are provided on the shoulder land portion 3. Such a shoulder sipe 13 scratches the snow and ice road surface by its edge, and thus improves the snow and ice road performance.

In this embodiment, the shoulder sipe 13 extends outward in the tire axial direction from the vertical narrow groove 10. Such a shoulder sipe 13 provides a large edge. The shoulder sipe 13 is not limited to such an aspect, and may be arranged, for example, at a distance from the vertical narrow groove 10 on the outer side in the tire axial direction.

In the present embodiment, each shoulder sipe 13 includes an inner inclined portion 15 arranged on the vertical narrow groove 10 side and an outer inclined portion 16 arranged outside the inner inclined portion 15 in the tire axial direction.

Each inner inclined portion 15 is inclined with respect to the tire axial direction at an angle β larger than the angle α of the middle sipe 11. Such an inner inclined portion 15 provides a relatively long tire circumferential edge and enhances turning performance on snow and ice roads. On the other hand, the inner inclined portion 15 tends to reduce the tire axial rigidity of the shoulder land portion 3 and the shoulder land portion 3, but as described above, by providing the inner inclined portion 15 on the vertical narrow groove 10 side, the shoulder land portion 3 and the middle portion 3 and the middle portion are provided even when traveling under heavy load. The land portion 4 and the vertical groove 10 are closed and integrated. Therefore, the above-mentioned inconvenience can be prevented.

In the present embodiment, the inner inclined portion 15 is inclined to one side (upward to the left in the figure) with respect to the tire axial direction. Such an inner inclined portion 15 can alleviate a decrease in the rigidity of the shoulder land portion 3 and maintain steering stability performance on a dry road surface.

In order to effectively exert the above-mentioned action, it is desirable that the difference (β-α) between the angle β and the angle α is, for example, 5 to 25 degrees. The angle β is preferably, for example, 20 to 30 degrees.

The outer inclined portion 16 is connected to the outer end of the inner inclined portion 15 in the tire axial direction and is inclined with respect to the inner inclined portion 15. As a result, the shoulder sipe 13 provides edges at different angles with respect to the tire axial direction, thus improving snow and ice road performance. In the present embodiment, the outer inclined portion 16 has an angle γ in the tire axial direction smaller than the angle β. Such an outer inclined portion 16 enhances the scratching force due to the edge in the tire axial direction, and enhances the straight running stability performance on snow and ice roads.

In order to effectively exert the above-mentioned action, the angle γ of the outer inclined portion 16 is preferably, for example, 15 ° or less, and more preferably 5 ° or less.

In the present embodiment, the length L1 of the outer inclined portion 16 in the tire axial direction is formed to be larger than the length L2 of the inner inclined portion 15 in the tire axial direction. As a result, a decrease in the tire axial rigidity of the shoulder land portion 3 is suppressed. In order to improve the turning performance on snow and ice roads while ensuring such an action, the length L1 of the outer inclined portion 16 is preferably 1.3 to 2.3 times the length L2 of the inner inclined portion 15, for example. ..

Each shoulder sipe 13 has a tire circumferential pitch P2 having the same size. As a result, the rigidity in the tire circumferential direction between the shoulder sipes 13 and 13 is made uniform, so that the uneven wear resistance performance is improved.

In the present embodiment, the shoulder sipe 13 communicates with the shoulder slot 18 extending inward in the tire axial direction from the tread end Te. The shoulder slot 18 can smoothly discharge snow, ice, or the like containing water generated by cutting the snow-ice path in the shoulder sipe 13 toward the tread end Te side. In this embodiment, the shoulder slot 18 communicates with the outer inclined portion 16.

It is desirable that the length L3 of the shoulder slot 18 in the tire axial direction is smaller than the length L2 of the inner inclined portion 15. As a result, the decrease in the rigidity of the shoulder land portion 3 is suppressed. It is more desirable that the length L3 of the shoulder slot 18 is 10% to 30% of the length L2 of the inner inclined portion 15.

FIG. 3 is an enlarged view of the shoulder land portion 3 and the middle land portion 4 on the left side of FIG. As shown in FIG. 3, the shoulder land portion 3 of the present embodiment is further provided with a plurality of shoulder lateral grooves 20 for dividing the shoulder land portion 3 into a plurality of shoulder blocks 3A. The inner end 20i of the shoulder lateral groove 20 in the tire axial direction communicates with the vertical narrow groove 10 in the present embodiment.

In the present embodiment, the shoulder lateral groove 20 includes an inner portion 21 arranged on the vertical narrow groove 10 side and an outer portion 22 arranged on the outer side of the inner portion 21 in the tire axial direction.

The inner portion 21 extends along the inner inclined portion 15 in the present embodiment. The outer portion 22 extends along the outer inclined portion 16 in the present embodiment. As a result, the tire circumferential rigidity of the shoulder block 3A between the shoulder lateral groove 20 and the shoulder sipe 13 is made uniform along the tire axial direction, so that the uneven wear resistance performance is improved. In the present specification, "the lateral groove extends along the sipe" means that the angle between the amplitude center line n of the sipe and the groove center line c of the lateral groove includes, of course, 0 degrees. It refers to an aspect of 5 degrees or less.

The outer portion 22 is inclined with respect to the inner portion 21. Such a shoulder lateral groove 20 provides edges at different angles with respect to the tire axial direction depending on the groove edge, thus improving snow and ice road performance.

It is desirable that the absolute value | β-θ1 | of the difference between the angle θ1 of the inner portion 21 with respect to the tire axial direction and the angle β (shown in FIG. 2) of the inner inclined portion 15 is 5 degrees or less. When the absolute value | β-θ1 | exceeds 5 degrees, the shoulder block 3A between the inner portion 21 and the inner inclined portion 15 has a large change in tire circumferential rigidity along the tire axial direction, and thus is resistant to uneven wear. Performance may deteriorate. Therefore, it is more desirable that the absolute value | β-θ1 | is 2 degrees or less.

Although not particularly limited, the angle θ1 of the inner portion 21 is preferably 20 to 30 degrees, for example.

From the viewpoint of effectively exerting the above-mentioned action, the absolute value | γ-θ2 | of the difference between the angle θ2 of the outer portion 22 with respect to the tire axial direction and the angle γ (shown in FIG. 2) of the outer inclined portion 16 is 5. It is preferably less than or equal to the degree, and even more preferably less than or equal to 2 degrees.

It is desirable that the absolute value | L2-L4 | of the difference between the length L4 of the inner portion 21 in the tire axial direction and the length L2 of the inner inclined portion 15 in the tire axial direction (shown in FIG. 2) is small. As a result, the above-mentioned action is further effectively exerted. The absolute value | L2-L4 | is preferably, for example, 5 mm or less, and more preferably 3 mm or less.

In the present embodiment, the outer portion 22 has the same width in the tire circumferential direction as the inner portion 21, and the width in the tire circumferential direction gradually increases between the equal width portion 22a and the tread end Te. It includes a gradual increase portion 22b. Such an outer portion 22 maintains high rigidity of the shoulder land portion 3 and more smoothly discharges snow, ice, etc. accumulated in the outer portion 22 to the outside of the tread end Te.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. As shown in FIG. 4, in the present embodiment, the groove depth d1 of the inner portion 21 is formed to be smaller than the groove depth d2 of the outer portion 22. As a result, snow, ice, and the like can be smoothly discharged to the outside of the tread end Te while maintaining the rigidity of the shoulder land portion 3. The groove depth d1 of the inner portion 21 is preferably 70% to 95% of the groove depth d2 of the outer portion 22, for example. Further, it is desirable that the groove depth d1 of the inner portion 21 is, for example, 50% to 90% of the groove depth D1 of the main groove 6.

As shown in FIG. 3, in the present embodiment, the middle land portion 4 is provided with a plurality of middle lateral grooves 24 that divide the middle land portion 4 into a plurality of middle blocks 4A. Since the groove edge of such a middle lateral groove 24 scratches the snow and ice road surface, the snow and ice road performance is improved.

Each middle lateral groove 24 extends along the middle sipe 11 in this embodiment. As a result, the tire circumferential rigidity of the middle block 4A between the middle lateral groove 24 and the middle sipe 11 is made uniform in the tire axial direction, so that uneven wear resistance is maintained high.

Each middle lateral groove 24 has a constant groove width and extends linearly. Such a middle lateral groove 24 further maintains high rigidity of the middle land portion 4.

It is desirable that the outer end 24e of the middle lateral groove 24 in the tire axial direction is provided at a position where it does not overlap with the inner end 20i of the shoulder lateral groove 20 in the tire axial direction in the tire circumferential direction. As a result, the middle land portion 4 and the shoulder land portion 3 support each other more effectively, and the apparent rigidity is increased, so that the steering stability performance on a dry road surface is further maintained. The "non-overlapping" means that the outer end of one of the groove edges in the tire circumferential direction of the middle lateral groove 24 is at least in the tire circumferential direction than the inner end of the other groove edge in the tire circumferential direction of the shoulder lateral groove 20. It means that it is located on the other side.

The outer end 24e of the middle lateral groove 24 is located at the central portion 25 including the intermediate position 3c of the shoulder block 3A in the tire circumferential direction. As a result, the above-mentioned action is enhanced. The central portion 25 is a region within 35% of the length La of the shoulder block 3A in the tire circumferential direction from the intermediate position 3c of the shoulder block 3A to both sides in the tire circumferential direction.

As shown in FIG. 4, the middle lateral groove 24 connects the middle outer portion 24a communicating with the vertical narrow groove 10 and the middle outer portion 24a and the middle main groove 7, and has a groove depth larger than that of the middle outer portion 24a. Includes a middle inner portion 24b with. As a result, snow, ice, and the like in the middle lateral groove 24 are smoothly discharged to the middle main groove 7 having a large groove width, so that the snow and ice road performance is improved. Further, since such a middle lateral groove 24 suppresses a decrease in the rigidity of the middle land portion 4, the steering stability performance on a dry road surface is maintained high.

In order to effectively exert such an action, the groove depth d3 of the middle outer portion 24a is preferably 50% to 80% of the groove depth d4 of the middle inner portion 24b. Further, the groove depth d4 of the middle inner portion 24b is preferably 60% to 80% of the groove depth D1 of the middle main groove 7.

As shown in FIG. 3, in the middle land portion 4, the width Wm in the tire axial direction repeatedly increases and decreases in the tire circumferential direction. As a result, the middle land portion 4 has a wide portion 4a in which the width Wm in the tire axial direction is larger than the average width in the tire axial direction and a narrow portion 4a in which the width Wm in the tire axial direction is smaller than the average width in the tire axial direction. It has a part 4b. In the present specification, the average of the widths is calculated excluding the middle land portion 4 of the projection region T in the tire axial direction of the middle lateral groove 24.

The wide portion 4a of the present embodiment communicates with the inner end 20i of the shoulder lateral groove 20 in the tire axial direction. As a result, the shoulder block 3A near the shoulder lateral groove 20 having a relatively low rigidity is adjacent to the wide portion 4a having a relatively large rigidity in the tire axial direction, so that a large collapse of the shoulder land portion 3 is suppressed. Therefore, steering stability performance and uneven wear resistance performance on a dry road surface are improved.

The middle land portion 4 has a minimum width portion 26 having a minimum width in the tire axial direction. The minimum width portion 26 of the present embodiment is a protruding position in which the groove edge 7a on the outer side of the middle main groove 7 in the tire axial direction is convex toward the outer side in the tire axial direction. In the present specification, the minimum width portion 26 excludes the projection region T of the middle lateral groove 24.

The minimum width portion 26 is not provided with the middle lateral groove 24. Further, in the minimum width portion 26, the inner end 20i of the shoulder lateral groove 20 in the tire axial direction is displaced. As a result, in the middle land portion 4, the decrease in rigidity of the minimum width portion 26 is suppressed, so that the uneven wear resistance performance is maintained high.

FIG. 5 is an enlarged view of the crown land portion 5 on the left side of FIG. As shown in FIG. 5, in the present embodiment, the crown land portion 5 is provided with a plurality of crown lateral grooves 30, a crown lug groove 31, and a crown sipe 32, respectively.

Each crown lateral groove 30 connects the crown main groove 8 and the middle main groove 7, and divides the crown land portion 5 into a plurality of crown blocks 5A. In the present embodiment, the crown lateral groove 30 is inclined to one side with respect to the tire axial direction and extends linearly. Such a crown lateral groove 30 provides an edge in the tire circumferential direction and improves snow and ice road performance.

The outer end 30e of the crown lateral groove 30 in the tire axial direction communicates with a protruding position 35 in which the groove edge 7b on the inner side of the middle main groove 7 in the tire axial direction is convex outward in the tire axial direction. As a result, the rigidity of the crown land portion 5 in the tire axial direction is made uniform along the tire circumferential direction, so that the uneven wear resistance performance is improved.

In the present embodiment, the crown lug groove 31 is inclined in the same direction as the crown lateral groove 30. Such a crown lug groove 31 can reduce the step of the tire circumferential rigidity of the crown land portion 5.

The crown lug groove 31 of the present embodiment is inclined at a larger angle with respect to the tire axial direction than the crown lateral groove 30. The crown lug groove 31 provides a relatively long tire circumferential edge and enhances turning performance on snow and ice roads.

The crown sipe 32 is inclined in the same direction as the crown lug groove 31. Such a crown sipe 32 can reduce the step of the tire circumferential rigidity of the crown land portion 5.

The crown sipe 32 is inclined at a larger angle with respect to the tire axial direction than the crown lateral groove 30. The crown sipe 32 provides a relatively long tire circumferential edge to enhance turning performance on snow and ice roads.

The crown sipe 32 includes a first crown sipe 32A, a second crown sipe 32B, and a third crown sipe 32C. The first crown sipe 32A connects the crown main groove 8 and the middle main groove 7. The second crown sipe 32B extends from the crown main groove 8 toward the outside in the tire axial direction and terminates in the crown block 5A. The third crown sipe 32C extends inward in the tire axial direction from the middle main groove 7 and terminates in the crown block 5A. The crown sipe 32 is not limited to such an embodiment.

Each crown sipe 32 provided in the crown block 5A has a tire circumferential pitch P3 having the same size. As a result, the rigidity in the tire circumferential direction between the crown sipes 32 and 32 is made uniform, so that the uneven wear resistance performance is improved.

Although the embodiments of the present invention have been described in detail above, it goes without saying that the present invention is not limited to the exemplary embodiments and can be modified into various embodiments.

Tires of size 205 / 65R16 with the basic pattern of FIG. 1 were prototyped based on the specifications in Table 1, and the snow and ice road performance, steering stability performance on dry road surface, and uneven wear resistance performance of each test tire were tested. .. The main common specifications and test methods for each test tire are as follows.
Height of each main groove: 10 mm
Tread ground contact width TW: 176 mm

<Snow and ice road performance / steering stability performance on dry roads>
Each test tire was mounted on all wheels of a four-wheel drive vehicle with a displacement of 3600 cc under the following conditions. Then, the test driver ran the test course on the snow-ice road surface and the dry asphalt road surface, and the traction, running stability, and turning characteristics at this time were evaluated by the sensuality of the test driver. The result is displayed with a score of 100 in Comparative Example 1. The larger the number, the better.
Rim: 6.5J
Internal pressure: 390kPa (front wheels), 350kPa (rear wheels)

<Uneven wear resistance>
Using the above vehicle, the test tire was run 10,000 km on a test course on a dry asphalt road surface, and then the difference in the amount of wear due to heel and toe wear was measured in the shoulder block and the middle block. The result is displayed as an index with the value of Comparative Example 1 as 100 using the reciprocal of the measured value. The larger the number, the better.
The test results and the like are shown in Table 1.

As a result of the test, it was confirmed that the tires of the examples had improved snow and ice road performance while maintaining the steering stability performance on a dry road surface as compared with the tires of the comparative example. In addition, the uneven wear resistance is also maintained high.

1 Tire 2 Tread part 3 Shoulder land part 4 Middle land part 10 Vertical groove 11 Middle sipe 13 Shoulder sipe 15 Inner slope

Claims (7)

In the tread portion, the shoulder land portion arranged on the most tread end side, the middle land portion arranged adjacent to the inside of the shoulder land portion in the tire axial direction, and between the shoulder land portion and the middle land portion. Is provided with vertical grooves that extend in the tire circumferential direction.
A plurality of middle sipes having an angle α with respect to the tire axial direction are provided on the middle land portion.
A plurality of shoulder sipes are provided on the shoulder land portion.
It said plurality of shoulder sipes, the longitudinal narrow groove side, have a inner inclined portion inclined with respect to the tire axial direction by said angle α greater angle than the Midorusaipu beta,
The shoulder land portion is provided with a plurality of shoulder lateral grooves that divide the shoulder land portion into a plurality of shoulder blocks.
The shoulder lateral groove has an inner portion arranged on the vertical narrow groove side.
The absolute value of the difference between the angle of the inner portion with respect to the tire axial direction and the angle β of the inner inclined portion is 5 degrees or less.
The shoulder lateral groove has an outer portion on the outer side in the tire axial direction of the inner portion.
The outer portion is inclined with respect to the inner portion.
tire. The middle land portion has a plurality of middle lateral grooves that divide the middle land portion into a plurality of middle blocks.
The tire according to claim 1 , wherein the outer end of the middle lateral groove in the tire axial direction is provided at a position where it does not overlap with the inner end of the shoulder lateral groove in the tire axial direction in the tire circumferential direction. The middle land portion has a wide portion in which the width in the tire axial direction repeatedly increases and decreases in the tire circumferential direction and has a width in the tire axial direction larger than the average width in the tire axial direction.
The tire according to claim 1 or 2 , wherein the inner end of the shoulder lateral groove in the tire axial direction communicates with the wide portion . In the tread portion, the shoulder land portion arranged on the most tread end side, the middle land portion arranged adjacent to the inner side of the shoulder land portion in the tire axial direction, and between the shoulder land portion and the middle land portion. Is provided with vertical grooves that extend in the tire circumferential direction.
A plurality of middle sipes having an angle α with respect to the tire axial direction are provided on the middle land portion.
A plurality of shoulder sipes are provided on the shoulder land portion.
The plurality of shoulder sipes have an inner inclined portion inclined in the tire axial direction at an angle β larger than the angle α of the middle sipe on the vertical narrow groove side.
The shoulder land portion is provided with a plurality of shoulder lateral grooves that divide the shoulder land portion into a plurality of shoulder blocks.
The middle land portion has a plurality of middle lateral grooves that divide the middle land portion into a plurality of middle blocks.
The outer end of the middle lateral groove in the tire axial direction is located at the central portion including the intermediate position in the tire circumferential direction of the shoulder block.
The middle land portion has a minimum width portion that minimizes the width in the tire axial direction.
The middle lateral groove is not provided in the minimum width portion, and the inner end of the shoulder lateral groove in the tire axial direction is displaced.
tire. The shoulder sipe has an outer inclined portion on the outer side in the tire axial direction of the inner inclined portion.
The tire according to any one of claims 1 to 4, wherein the outer inclined portion is inclined with respect to the inner inclined portion. The tire according to any one of claims 1 to 5, wherein the middle sipe has a first middle sipe and a second middle sipe having a depth larger than that of the first middle sipe alternately in the tire circumferential direction. The tire according to any one of claims 1 to 6, wherein a middle main groove extending in a zigzag shape continuously in the tire axial direction inside the middle land portion in the tire axial direction is provided.

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