JP2018162051A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve performance on a snowy and icy road while keeping steering stability performance of a dry road surface.SOLUTION: A tire 1 has a shoulder land part 3, a middle land part 4 and a vertical thin groove 10 extending in a tire circumferential direction between the shoulder land part 3 and the middle land part 4 provided on a tread part 2. In the middle land part 4, a plurality of middle sipes 11 having an angle α with respect to a tire axial direction are provided. In the shoulder land part 3, a plurality of shoulder sipes 13 are provided. The shoulder sipe 13 has an inside inclined part 15 which is inclined in the tire axial direction with an angle β larger than the angle α of the middle sipe 11 on the side of the vertical thin groove 10.SELECTED DRAWING: Figure 1

Description

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

  For example, various types of tires have been proposed for the purpose of traveling on a snowy road surface or an icy road surface (hereinafter, these road surfaces may be collectively referred to as “snow / ice road surface”). A narrow slit-shaped sipe is formed in each land portion of this type of tire. Such a tire increases 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 sometimes 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.

JP 2011-42328 A

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

  The present invention provides a shoulder land portion disposed on the tread portion at the most tread end side, a middle land portion disposed adjacent to the inner side in the tire axial direction of the shoulder land portion, and the shoulder land portion and the middle land. Are provided with a plurality of middle sipes having an angle α with respect to the tire axial direction, and the shoulder land portion includes a plurality of middle sipes. The plurality of shoulder sipes are tires having an inner inclined portion that is inclined with respect to the tire axial direction at an angle β larger than the angle α of the middle sipe on the longitudinal narrow groove side. is there.

  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 that divide 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 disposed on the vertical narrow groove side, and an absolute difference between an angle of the inner portion with respect to the tire axial direction and the angle β of the inner inclined portion is determined. The value is desirably 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.

  In the tire according to the present invention, the middle land portion includes a plurality of middle lateral grooves that divide the middle land portion into a plurality of middle blocks, and an outer end of the middle lateral groove in a tire axial direction is the shoulder lateral groove. It is desirable to be provided at a position that does not overlap with the inner end of the tire 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 has a width in the tire axial direction that is larger than the average of the width in the tire axial direction. It has a wide part, and it is desirable that the inner end of the shoulder lateral groove in the tire axial direction communicates with the wide part.

  In the tire according to the present invention, the middle land portion has a plurality of middle lateral grooves 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 in which the width in the tire axial direction is minimum, the middle width groove is not provided in the minimum width portion, and the shoulder width groove It is desirable that the inner end in the tire axial direction is displaced.

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

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

  In the invention described in claim 11, it is preferable that a middle main groove extending in a zigzag manner continuously in the tire circumferential direction on the inner side in the tire axial direction of the middle land portion is provided.

  In the tire of the present invention, the tread portion is provided with a shoulder land portion, a middle land portion, and a vertical 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 during turning, the shoulder land portion and the middle land portion can support each other and have high rigidity in appearance. Therefore, the tire of the present invention can maintain the steering stability performance on the dry road surface.

  A plurality of middle sipes are provided in the middle land portion. The shoulder land portion is provided with a plurality of shoulder sipes. Each of these sipes can scratch the snow and ice road surface by its edge, thereby improving the snow and ice road performance.

  The shoulder sipe has an inner inclined portion that is inclined at an angle larger than an angle of the middle sipe with respect to the tire axial direction on the longitudinal narrow groove side. The inner slope provides a relatively long tire circumferential edge and improves turning performance on snow and ice roads. On the other hand, the inner slope part tends to reduce the tire axial rigidity of the shoulder land part.However, as described above, the shoulder land part and the middle land part are vertically arranged even at high loads by being provided on the longitudinal narrow groove side. Such inconvenience can be prevented by closing and integrating the narrow grooves.

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

It is an expanded view of the tread part of one Embodiment of this invention. It is an enlarged view of a middle land part and a shoulder land part. It is an enlarged view of a middle land part and a shoulder land part. It is the sectional view on the AA line of FIG. It is an enlarged view of a crown land part.

Hereinafter, an embodiment of the present invention 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 invention. In this embodiment, a pneumatic tire for a passenger car is shown as a preferable aspect. However, it goes without saying that the present invention can also be applied to other categories of tires 1 such as for heavy loads.

  As shown in FIG. 1, a shoulder land portion 3, a middle land portion 4, and a crown land portion 5 are provided in the tread portion 2 of the present embodiment. 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 inner side in the tire axial direction of the shoulder land portion 3. The crown land portion 5 is disposed adjacent to the inner side of the middle land portion 4 in the tire axial direction.

  The “tread end” Te is a normal load obtained by applying a normal load to a flat tire with a camber angle of 0 degrees on a normal tire 1 in a normal state in which a normal rim is assembled and filled with a normal internal pressure. It is determined as the ground contact position on the outermost side in the tire axial direction in the loaded state. In the normal state, the distance in the tire axial direction between the tread ends Te and Te is determined as the tread contact width TW. When there is no notice in particular, the dimension of each part of the tire 1 is a value measured in a normal state.

  The “regular rim” is a rim determined 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, “ETRTO” Then "Measuring Rim".

  “Normal internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JATIMA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. It is “Maximum load capacity” for JATMA and “TIRE LOAD” for TRA. The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in ETRTO.

  The tread portion 2 is provided with a main groove 6 extending 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 inward in the tire axial direction of the middle land portion 4. The middle main groove 7 divides the middle land portion 4 and the crown land portion 5 in this embodiment. The crown main groove 8 extends on the inner side in the tire axial direction of the crown land portion 5. In this embodiment, the crown main groove 8 divides the pair of crown land portions 5 and 5.

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

  The crown main groove 8 extends linearly in the tire circumferential direction, for example. Such a crown main groove 8 maintains high rigidity in the tire circumferential direction of the crown land portion 5 in the vicinity of the tire equator C where a large contact pressure acts, and thus improves uneven wear resistance. The main groove 6 is not limited to such an embodiment.

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

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

  The vertical thin 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 thin 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 consequently 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 joins the middle main groove 7 and the vertical narrow groove 10. The middle sipe 11 is inclined to one side (upward 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 greater than 0 degrees, for example. Since such a middle sipe 11 provides an edge in the tire circumferential direction, the turning performance on snowy and ice roads is enhanced. When the angle α is excessively large, provision of edges in the tire circumferential direction becomes excessively large, and there is a concern that the straight running stability performance on snowy and ice roads may be deteriorated. For this reason, the angle α is preferably 5 to 20 degrees.

  The middle sipes 11 alternately have first middle sipes 11a and second middle sipes 11b having a depth greater than that of the first middle sipes 11a in the tire circumferential direction. Such a middle sipe 11 can improve the snow / ice road performance due to the edge while suppressing a decrease in 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 depth of the middle main groove 7. The depth of the second middle sipe 11b is desirably 70% to 80% of the depth of the middle main groove 7.

  In the present embodiment, the middle sipe 11 extends in a zigzag shape. Such a middle sipe 11 maintains the rigidity of the middle land portion 4 high in appearance because the land portions on both sides of the sipe support each other when a load is applied during turning. In the present specification, the angle of the sipe extending in a zigzag shape with respect to the tire axial direction is an angle between the zigzag amplitude center line n and the tire axial direction line. Further, the sipe of the present embodiment is not limited to a zigzag shape.

  Each middle sipe 11 is formed with the same tire circumferential pitch P1. Thereby, since the tire circumferential rigidity between the middle sipes 11, 11 is made uniform, the uneven wear resistance performance is improved.

  The shoulder land portion 3 is provided with a plurality of shoulder sipes 13. Such a shoulder sipe 13 scratches the snow and ice road surface by its edge, thereby improving the snow and ice road performance.

  In this embodiment, the shoulder sipe 13 extends from the longitudinal groove 10 toward the outer side in the tire axial direction. Such a shoulder sipe 13 provides a large edge. In addition, the shoulder sipe 13 is not limited to such an aspect, For example, the shoulder sipe 13 may be spaced apart from the vertical thin groove 10 to the outer side in the tire axial direction.

  In the present embodiment, each shoulder sipe 13 includes an inner inclined portion 15 disposed on the longitudinal groove 10 side and an outer inclined portion 16 disposed on the outer side in the tire axial direction than the inner inclined portion 15.

  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 edge in the tire circumferential direction, and improves turning performance on snowy and ice roads. On the other hand, the inner inclined portion 15 is easy to reduce the rigidity of the shoulder land portion 3 in the tire axial direction. However, as described above, by providing the shoulder land portion 3 on the vertical narrow groove 10 side, The land portion 4 is integrated by closing the vertical narrow groove 10. For this reason, the above inconveniences can be prevented.

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

  In order to effectively exhibit the above-described action, the difference (β−α) between the angle β and the angle α is preferably, for example, 5 to 25 degrees. Further, the angle β is preferably 20 to 30 degrees, for example.

  The outer inclined portion 16 is connected to the outer end in the tire axial direction of the inner inclined portion 15 and is inclined with respect to the inner inclined portion 15. Thereby, since the shoulder sipe 13 provides the edge of a different angle with respect to a tire axial direction, snow and ice road performance is improved. In the present embodiment, the outer inclined portion 16 has an angle γ in the tire axial direction that is smaller than the angle β. Such an outer inclined portion 16 increases the scratching force caused by the edge in the tire axial direction, and improves the straight running stability performance on snowy and ice roads.

  In order to effectively exhibit the above-described action, the angle γ of the outer inclined portion 16 is preferably 15 ° or less, for example, 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 greater than the length L2 of the inner inclined portion 15 in the tire axial direction. Thereby, the fall of the tire axial direction rigidity of the shoulder land part 3 is suppressed. In order to improve the turning performance on the snowy and ice road 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 is formed with the same tire circumferential pitch P2. As a result, the tire circumferential rigidity between the shoulder sipes 13 and 13 is made uniform, so that uneven wear resistance is improved.

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

  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. Thereby, the fall of the rigidity of the shoulder land part 3 is suppressed. The length L3 of the shoulder slot 18 is more preferably 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 that divide the shoulder land portion 3 into a plurality of shoulder blocks 3A. The inner end 20i in the tire axial direction of the shoulder lateral groove 20 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 disposed on the vertical narrow groove 10 side and an outer portion 22 disposed on the outer side in the tire axial direction of the inner portion 21.

  The inner portion 21 extends along the inner inclined portion 15 in the present embodiment. In the present embodiment, the outer portion 22 extends along the outer inclined portion 16. Thereby, since the tire circumferential direction 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, the uneven wear resistance performance is improved. In this 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 an aspect in which the angle is 0 degrees. 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 an edge having a different angle with respect to the tire axial direction depending on the groove edge, thereby improving snow and ice road performance.

  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 desirably 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. Performance may deteriorate. For this reason, the absolute value | β−θ1 | is more preferably 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-described 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 degrees, and more preferably less than or equal to 2 degrees.

  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 preferably small. Thereby, the above-described action is further effectively exhibited. 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 a uniform width portion 22a having 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. The gradually increasing portion 22b is included. Such an outer portion 22 discharges snow and ice accumulated in the outer portion 22 to the outside of the tread end Te more smoothly while maintaining the rigidity of the shoulder land portion 3 high.

  4 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 4, in this embodiment, the groove depth d <b> 1 of the inner part 21 is formed smaller than the groove depth d <b> 2 of the outer part 22. Thereby, snow, ice, etc. can be discharged | emitted smoothly to the outer side of the tread end Te, maintaining the rigidity of the shoulder land part 3. FIG. The groove depth d1 of the inner part 21 is desirably 70% to 95% of the groove depth d2 of the outer part 22, for example. Moreover, 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, 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 in the present embodiment. Such a middle lateral groove 24 improves the snow / ice road performance because the edge of the groove scratches the snow / ice road surface.

  Each middle lateral groove 24 extends along the middle sipe 11 in this embodiment. Accordingly, the rigidity in the tire circumferential direction 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 high uneven wear resistance is maintained.

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

  The outer end 24e of the middle lateral groove 24 in the tire axial direction is preferably provided at a position that 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 enhanced, so that the steering stability performance on the dry road surface is further maintained. The term “does not overlap” means that the outer end of one groove edge 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 is located on the other side.

  The outer end 24e of the middle lateral groove 24 is located at a central portion 25 including an intermediate position 3c in the tire circumferential direction of the shoulder block 3A. Thereby, the above-mentioned operation is enhanced. The central portion 25 is an area within a range of 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 has a middle outer portion 24a communicating with the vertical narrow groove 10, and a groove depth that joins the middle outer portion 24a and the middle main groove 7 and is larger than the middle outer portion 24a. The middle inner part 24b having As a result, snow, ice, and the like in the middle lateral groove 24 are smoothly discharged into the middle main groove 7 having a large groove width, so that snow and ice road performance is improved. Moreover, since such a middle horizontal groove 24 suppresses the fall of the rigidity of the middle land part 4, the steering stability performance on a dry road surface is maintained high.

  In order to effectively exhibit such an action, the groove depth d3 of the middle outer portion 24a is desirably 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. Accordingly, 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 width in which the width Wm in the tire axial direction is smaller than the average width in the tire axial direction. Part 4b. In the present specification, the average of the width 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 inner end 20i of the shoulder lateral groove 20 in the tire axial direction communicates with the wide portion 4a of the present embodiment. As a result, the shoulder block 3A in the vicinity of the shoulder lateral groove 20 having relatively low rigidity is adjacent to the wide part 4a having relatively high rigidity in the tire axial direction, so that the large collapse of the shoulder land portion 3 is suppressed. Therefore, steering stability performance and uneven wear resistance performance on dry road surfaces 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 where the groove edge 7a on the outer side in the tire axial direction of the middle main groove 7 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 middle width groove 24 is not provided in the minimum width portion 26. Further, the inner end 20 i of the shoulder lateral groove 20 in the tire axial direction is displaced from the minimum width portion 26. Thereby, in the middle land part 4, since the rigidity fall of the minimum width part 26 is suppressed, uneven wear-proof 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, the crown land portion 5 is provided with a plurality of crown lateral grooves 30, crown lug grooves 31, and crown sipes 32 in the present embodiment.

  Each of the crown lateral grooves 30 joins the crown main groove 8 and the middle main groove 7 to divide the crown land portion 5 into a plurality of crown blocks 5A. In this embodiment, the crown lateral groove 30 is inclined in one direction 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.

  An outer end 30e in the tire axial direction of the crown lateral groove 30 communicates with a protruding position 35 where a groove edge 7b on the inner side in the tire axial direction of the middle main groove 7 protrudes outward in the tire axial direction. Thereby, since the rigidity of the crown land portion 5 in the tire axial direction is made uniform along the tire circumferential direction, uneven wear resistance 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 in the tire circumferential direction rigidity of the crown land portion 5.

  The crown lug groove 31 of the present embodiment is inclined at a greater angle than the crown lateral groove 30 with respect to the tire axial direction. The crown lug groove 31 provides a relatively long edge in the tire circumferential direction, and improves the turning performance on snowy 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 in 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 and improves turning performance on a snowy and ice road.

  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 continues 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 outer side in the tire axial direction and terminates in the crown block 5A. The third crown sipe 32C extends from the middle main groove 7 toward the inside in the tire axial direction and terminates in the crown block 5A. The crown sipe 32 is not limited to such a mode.

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

  As mentioned above, although embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention is not limited to exemplary embodiment, and can be deform | transformed and implemented in a various aspect.

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

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

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

  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 the dry road surface as compared with the tires of the comparative examples. Further, the uneven wear resistance performance is also maintained high.

DESCRIPTION OF SYMBOLS 1 Tire 2 Tread part 3 Shoulder land part 4 Middle land part 10 Longitudinal groove 11 Middle sipe 13 Shoulder sipe 15 Inner inclination part

Claims (11)

A shoulder land portion disposed on the tread portion at the most tread end side, a middle land portion disposed adjacent to the inner side in the tire axial direction of the shoulder land portion, and between the shoulder land portion and the middle land portion Is provided with a vertical narrow groove extending in the tire circumferential direction,
The middle land portion is provided with a plurality of middle sipes having an angle α with respect to the tire axial direction,
The shoulder land portion is provided with a plurality of shoulder sipes,
The plurality of shoulder sipes are tires having, on the longitudinal narrow groove side, an inner inclined portion that is inclined with respect to the tire axial direction at an angle β larger than the angle α of the middle sipe.   The tire according to claim 1, wherein 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 part arranged on the vertical narrow groove side,
The tire according to claim 2, wherein an absolute value of a difference between an angle of the inner portion with respect to a 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 tire according to claim 3, wherein the outer portion is inclined with respect to the inner portion. 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 any one of claims 2 to 4, wherein an outer end of the middle lateral groove in the tire axial direction is provided at a position not overlapping with an 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 repeats increasing and decreasing in the tire circumferential direction, and has a width in the tire axial direction that is larger than the average of the width in the tire axial direction,
The tire according to any one of claims 2 to 5, wherein an inner end of the shoulder lateral groove in the tire axial direction communicates with the wide portion. 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 any one of claims 2 to 6, wherein an outer end of the middle lateral groove in the tire axial direction is located at a central portion including an intermediate position of the shoulder block in the tire circumferential direction. The middle land portion has a minimum width portion where the width in the tire axial direction is minimum,
The tire according to claim 7, wherein the middle lateral groove is not provided in the minimum width portion, and an inner end of the shoulder lateral groove in the tire axial direction is displaced. 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 8, wherein the outer inclined portion is inclined with respect to the inner inclined portion.   The tire according to any one of claims 1 to 9, wherein the middle sipe alternately includes first middle sipe and second middle sipe having a depth greater than that of the first middle sipe.   The tire according to any one of claims 1 to 10, wherein a middle main groove extending in a zigzag manner continuously in the tire circumferential direction on the inner side in the tire axial direction of the middle land portion is provided.

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