JP6777521B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having an improved sipe arranged on a block of a tread portion.

Conventionally, as shown in Patent Documents 1 to 4 below, pneumatic tires in which a sipe is formed in a tread portion of a tire are known.

In the following Patent Document 1, for the purpose of facilitating the removal of pebbles caught in the lug groove, a main groove extending in the tire circumferential direction is provided on the tread surface, and a lug groove extending in the tire width direction is defined in the tire circumferential direction. Pneumatic tires for ice and snow roads, which are arranged at the same pitch, have a large number of blocks formed by the main grooves and lug grooves, and each block is provided with at least three sipes extending in the tire width direction. Each has a wide portion extending from the block surface toward the bottom of the groove, and the wide portion is provided on the sipe on the central region side rather than on the sipe on both sides in the tire circumferential direction. Pneumatic tires for deeper ice and snow roads are shown.

That is, it is shown that a wide portion is provided on the groove bottom side of the sipe, and the wide portion provided on the sipe on the central region side is deeper than the wide portion provided on the sipe on both sides in the tire circumferential direction. There is.

The following Patent Document 2 describes a circumferential groove extending in the circumferential direction and a lateral groove extending in the width direction for the purpose of improving steering stability and hydroplaning on a wet road surface while maintaining wear resistance of the block portion. In addition to partitioning the block by each of the above, a sipe extending in the tread width direction and opening to the peripheral groove at both ends is provided on the block surface, and the sipe is opened to the peripheral groove via the widening portion. , The block structure of the pneumatic tire is shown in which the depth of the widened portion is made shallower than that of the deepest portion of the sipe.

That is, it is shown that one type of sipe is provided in which widening portions are provided at both ends and the depth of the widening portion is shallower than the depth of the deepest portion of the sipe.

In Patent Document 3 below, one end is opened on the tread surface and the other end is closed for the purpose of suppressing the occurrence of heel-and-toe wear and block chipping, and further preventing cracks from the siping edge. In a tire provided with a plurality of treads, the thickness of the closed end of the sipe is set to be larger than the thickness of the open end, and the thickness of the sipe is gradually reduced from the closed end or its vicinity toward the open end. Pneumatic tires are shown in which the depth of the closed end of the sipe is greater than the depth of the open end.

That is, in a sipe with one end open and the other end closed, the opening width of the sipe on the open end side is gradually narrower than the opening width of the sipe on the closed end side, and the depth of the sipe on the closed end side is set on the open end side. It is shown to be deeper than the sipe depth.

In Patent Document 4 below, a large number of blocks are provided on the tread for the purpose of preventing step wear (calf cutting) for each calf and thus maintaining good ground contact between the tread and the icy road even after the middle stage of wear. In the inflated tire for ice and snow roads, the block is provided with three or more calfs in the tire width direction, and one end of these calfs is alternately communicated with grooves in the tire circumferential direction adjacent to both sides of the block. The two calfskin located at both outermost ends in the tire circumferential direction make the depth of the connecting portion connected to the groove in the tire circumferential direction shallower than the depth in the central region of the block width, and the groove in the tire circumferential direction. Pneumatic tires for ice and snow roads are shown, which are set to 30 to 40% of the groove depth of the tire and the width of the connecting portion is set to 5 to 15% of the width of the block.

That is, one ends of three or more sipes are alternately communicated with the tire circumferential groove, and the sipes located at both outermost ends in the tire circumferential direction set the groove depth of the connecting portion connected to the tire circumferential groove to the center of the block width. It is shown that the depth of the sipes in the region is shallower, the depth of the groove in the tire circumferential direction is set to 30 to 40%, and the width of the connecting portion is set to 5 to 15% of the width of the block.

Japanese Unexamined Patent Publication No. 11-139114 Japanese Unexamined Patent Publication No. 2001-233021 Japanese Unexamined Patent Publication No. 2-200503 Japanese Unexamined Patent Publication No. 8-216626

However, in the known techniques described in Patent Documents 1 to 4, there is a problem that the ice performance and the uneven wear suppressing performance are not compatible because the block rigidity is lowered by providing a large number of sipes.

In the present invention, the block rigidity is reduced by providing a large number of sipes by arranging two types of sipes having different groove depths in one sipes in the block and by changing the groove widths of these sipes. It is an object of the present invention to provide a pneumatic tire that achieves both ice performance and uneven wear suppression performance.

The pneumatic tire according to claim 1 of the present invention has a tire width in a tread portion of a block formed in a tire tread portion and which is divided into a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction. A plurality of sipe extending in a direction and opening at both ends thereof are formed, and the plurality of sipe is composed of a first sipe and a second sipe, and the first sipe and the second sipe are any of the above. The groove depth in the central region in the tire width direction is deeper than the groove depths at both ends in the tire width direction, and the groove depth in the central region in the tire width direction is the tire width direction of the second sipe. The groove depth of the first sipe is shallower than the groove depth of the central region, and the groove depths of both ends of the first sipe in the tire width direction are deeper than the groove depths of both ends of the second sipe in the tire width direction. The groove depth of the central region in the tire width direction is formed to be shallower than the groove depth of the main groove for partitioning the block, and the first sipes are arranged on both sides of the block in the tire circumferential direction. It is characterized by.

In the pneumatic tire according to the second aspect of the present invention, in addition to the configuration of the first aspect, the first sipe and the second sipe are alternately arranged in the tire circumferential direction in the block. It is characterized by that.

By combining the two types of sipes as described above, the sipe edges are increased, the tire rigidity is averaged, and the contact pressure with respect to the road surface is averaged, so that the edge effect of the sipes is improved and the ice performance is improved. By arranging sipe with shallow tire rigidity and shallow sipe at both ends, it is possible to suppress the collapse of the block and suppress uneven wear.

The pneumatic tire according to claim 3 of the present invention has a plurality of first sipes arranged on both sides in the tire circumferential direction in the block in addition to the configuration of claim 1, and has a central region in the tire circumferential direction. It is characterized by arranging a second sipe on the tire.

With the above configuration, in addition to the above action, the rigidity of the central region in the length direction at both ends in the block width direction is increased, whereas the rigidity of the four corners of the block is decreased, so that the grounding property is improved. Since it is improved, it has the effect of improving the turning performance on the ice road surface.

The pneumatic tire according to claim 4 according to the present invention has the configuration of claims 1 to 3 and the first sipe and the second sipe have a sipe width in the tire circumferential direction in the tire width direction. It is characterized by gradually spreading in a range of 1.5 to 3 times from the central region to both ends.

By gradually widening the sipe width from the central region to both ends of the sipe as described above, it is possible to make the edge of the sipe effective by eliminating the local rigidity difference and suppress uneven wear.

As described above, in the pneumatic tire according to the present invention, the block rigidity is averaged by the combination of the two types of sipes arranged in one block, and the decrease in the block rigidity is suppressed, so that the force applied to the ground is suppressed. It becomes uniform, an appropriate edge effect due to sipes on the ice road surface can be obtained, and the uneven wear suppressing performance by suppressing the block collapse is improved, so that both the ice road surface performance and the uneven wear suppressing effect can be achieved at the same time.

It is a schematic explanatory view of the block T (T1) which concerns on Example 1 of this invention, (a) is a plan view, (b) is a sectional view of groove A, (c) is a sectional view of groove B, (d). ) Is a sectional view taken along line EE (hatching omitted), and (e) is a sectional view taken along line FF (hatching omitted). An schematic explanatory view of the block T2 according to the second embodiment of the present invention, (a) is a plan view, (b) is a sectional view cut by a groove A, and (c) is a sectional view cut by a groove B. d) is a sectional view taken along line EE (hatching omitted), and (e) is a sectional view taken along line FF (hatching omitted). It is a schematic explanatory view of the block T3 which concerns on Example 2 of this invention, (a) is a plan view, (b) is a sectional view cut in groove A', (c) is a sectional view cut in groove B'. , (D) is a sectional view taken along line EE (hatching omitted), and (e) is a sectional view taken along line FF (hatching omitted). It is a schematic explanatory view of the block T4 which concerns on Comparative Example 1, (a) is a plan view, (b) is a sectional view cut by a groove C, (d) is a sectional view of line EE (hatching omitted), ( e) is a sectional view taken along line FF (hatching omitted). It is a schematic explanatory view of the block T5 which concerns on Comparative Example 2, (a) is a plan view, (b) is a sectional view cut by a groove B, (d) is a sectional view of line EE (hatching omitted), ( e) is a sectional view taken along line FF (hatching omitted). It is a schematic explanatory view of the block T6 which concerns on Comparative Example 3, (a) is a plan view, (b) is a sectional view cut by groove C, (c) is a sectional view cut by groove D, (d) is EE line sectional view (hatching omitted), (e) is FF line sectional view (hatching omitted).

FIG. 1 shows an embodiment of the present invention (FIG. 1 is used in combination with the first embodiment), and although not shown, a main groove extending in the tire circumferential direction and a tire width direction formed in a tire tread portion of a pneumatic tire It is a plurality of blocks formed by a lug groove extending to, and T in FIG. 1 represents one of the blocks.

In this embodiment, as shown in FIG. 1A, seven rows of sipes A and B extending in the tire width direction and having both ends open are arranged on the tread portion of the block T. Note that sipes A and B are not limited to seven rows.

As shown in FIGS. 1 (b) to 1 (e), each of the sipes A and B is composed of a first sipe A and a second sipe B having different groove depths. That is, in both the first sipe A and the second sipe B, the groove depths H1 and H3 in the central region in the tire width direction (FIG. 1 (e)) are the groove depths H2 and H4 at both ends in the tire width direction. It is formed deeper than FIG. 1 (d)).

In the first sipe A, the groove depth H1 in the central region in the tire width direction is shallower than the groove depth H3 in the central region in the tire width direction of the second sipe B, and the groove depth H3 in the tire width direction of the first sipe A is The groove depths H2 at both ends are formed deeper than the groove depths H4 at both ends of the second sipe B in the tire width direction (FIGS. 1B and 1C). The first sipes A are arranged on both sides of the block T in the tire circumferential direction. The second sipe B is formed so that the groove depth H3 in the central region in the tire width direction (the one having the deepest sipe groove in this embodiment) is shallower than the groove depth H of the main groove G that partitions the block T. (Fig. 1 (c)).

The length of one of both ends in the tire width direction where the groove depths H2 and H4 are located is in the range of 4 to 25% of the total length of the sipe, that is, the length of the central region where the groove depths H1 and H3 are located. It is appropriate that the tire is 50-92% of the total length of the sipe.

It is appropriate that the groove depth H1 of the central region in the first sipe A is in the range of 50 to 90% of the groove depth H3 of the central region in the second sipe B, and both ends in the first sipe A. It is appropriate that the groove depth H2 of the portion is in the range of 110 to 150% of the groove depth H4 of both ends of the second sipe B. Further, it is appropriate that the groove depth H3 in the central region of the second sipe B is in the range of 50 to 90% of the groove depth H of the main groove G, and the groove depths at both ends of the second sipe B. It is appropriate that H4 is in the range of 40 to 80% of the groove depth H3 in the central region.

In this embodiment, the first sipe A and the second sipe B are formed so that the sipe widths in the tire circumferential direction are the same. The range of the sipe width is 0.3 to 0.6 mm. Further, as shown in FIG. 3A of Example 3 described in detail below, the range of the sipe width gradually expands in the range of 1.5 to 3 times from the central region in the tire width direction to both ends. It may be configured as. For example, the sipe width in the central region is in the range of 0.3 to 0.6 mm, and the sipe width at both ends is in the range of 0.6 to 1.5 mm.

If it deviates from the above numerical range, the uniformity of the block rigidity may decrease, and the compatibility between the ice road surface performance and the uneven wear suppression performance may decrease.

Regarding the arrangement of the first sipe A and the second sipe B, as shown in FIG. 1A, the first sipe A is arranged on both sides in the tire circumferential direction, and the first sipe A inside the first sipe A is arranged. And the second sipes B may be arranged alternately in the tire circumferential direction, and as shown in FIG. 2A of the second embodiment described in detail below, a plurality of first sipes A may be arranged in the tire circumferential direction. It may be arranged on both sides, and the second sipe B may be arranged in the central region in the tire circumferential direction.

By combining two types of sipes with different groove depths as described above, the sipe edges are increased and the tire rigidity is averaged, and the first sipes A and A'on both sides in the tire circumferential direction at both ends in the tire width direction are Since the groove depth is made deeper than the groove depth of the second sipes B and B', the contact pressure with respect to the road surface is averaged, so that the edge of the sipes is effective and the turning performance is improved. By arranging sipe with shallow ends, the block collapse is suppressed, which has the effect of suppressing uneven wear.

In order to average the tire rigidity, the grooves of the first sipe A and the second sipe B may be symmetrical as shown in FIGS. 1 (b) and 1 (c), or the first The number of columns of the sipe A and the second sipe B may be equal to each other or the difference thereof may be reduced.

Example 1 of the present invention will be described below based on FIG. 1 used in the description of the above examples.

The groove depth H of the main groove G located outside the width direction of the block T1 in the first embodiment is 9 mm. In the first sipe A, the groove depth H1 in the central region in the tire width direction is 5.5 mm, the groove depth H2 at both ends in the tire width direction is 4.5 mm, and the sipe width w1 is 0.3 mm. The groove depth H3 in the central region in the tire width direction of the second sipe B is 6.5 mm, the groove depth H4 at both ends in the tire width direction is 3.5 mm, and the sipe width is the sipe width w1 of the first sipe A. It is 0.3 mm, which is the same as.

Then, in the first embodiment, as shown in FIG. 1A, the first sipes A are arranged in rows on both sides of the block T1 in the tire circumferential direction, and the first sipes A and the first sipes A are arranged therein. The second sipes B and the second sipes B are alternately arranged in the tire circumferential direction. That is, from one side of the block in the tire circumferential direction, the first sipe A, the second sipe B, the first sipe A, the second sipe B, the first sipe A, and the second sipe B , 7 rows of sipes are arranged in the order of the first sipes A.

Example 2 of the present invention will be described below with reference to FIG.

In the second embodiment, the groove configurations of the first sipe A and the second sipe B are the same as those in the first embodiment, and the arrangement of the sipe A and B is different from that of the first embodiment.

That is, the groove depth H of the main groove G located outside the width direction of the block T2 in the second embodiment is 9 mm. In the first sipe A, the groove depth H1 in the central region in the tire width direction is 5.5 mm, the groove depth H2 at both ends in the tire width direction is 4.5 mm, and the sipe width w1 is 0.3 mm. The groove depth H3 in the central region in the tire width direction of the second sipe B is 6.5 mm, the groove depth H4 at both ends in the tire width direction is 3.5 mm, and the sipe width is the sipe width w1 of the first sipe A. It is 0.3 mm, which is the same as.

Then, in the second embodiment, as shown in FIG. 2A, a plurality of first sipes A are arranged in two rows on each side of the block T2 in the tire circumferential direction, and the second sipes are arranged in the inner side thereof. B is arranged in three rows in the central region in the tire circumferential direction. That is, from one side of the block in the tire circumferential direction, the first sipe A, the first sipe A, the second sipe B, the second sipe B, the second sipe B, and the first sipe A , 7 rows of sipes are arranged in the order of the first sipes A.

Example 3 of the present invention will be described below with reference to FIG.

In the third embodiment, the arrangement of the first sipe A'and the second sipe B'is the same as that of the first embodiment, and the groove configuration of each sipe A'and B'is different from that of the first embodiment. , The sipe width in the tire circumferential direction is configured to gradually widen from the central region in the tire width direction to both ends.

That is, the groove depth H of the main groove G located outside the width direction of the block T3 in the third embodiment is 9 mm. In the first sipe A', the groove depth H1 in the central region in the tire width direction is 5.5 mm, the groove depth H2 at both ends in the tire width direction is 4.5 mm, and the sipe width w1 in the central region in the tire width direction is 0. It is .3 mm, and both ends in the tire width direction gradually widen from the sipe width w1 in the central region in the tire width direction, and the sipe width w2 at the sipe opening end is 0.6 mm, which is twice the sipe width w1. In the second sipe B', the groove depth H3 in the central region in the tire width direction is 6.5 mm, the groove depth H4 at both ends in the tire width direction is 3.5 mm, and the sipe width w1 in the central region in the tire width direction is 0. It is .3 mm, and both ends in the tire width direction gradually expand from the sipe width w1 in the central region in the tire width direction, and the sipe width w2 at the sipe opening end is 0.6 mm, which is twice the sipe width w1.

Then, in the third embodiment, as shown in FIG. 3A, the first sipe A'is arranged one row on each side of the block T3 in the tire circumferential direction, and the first sipe A'is arranged in the inside thereof. 'And the second sipe B'are arranged alternately in the tire circumferential direction. That is, from one side of the block in the tire circumferential direction, the first sipe A', the second sipe B', the first sipe A', the second sipe B', the first sipe A', Seven rows of sipe are arranged in the order of the second sipe B'and the first sipe A'.

Although illustration and description are omitted, the first sipe A'and the second sipe B'may be arranged as in the second embodiment.

[Comparative Example 1]
Comparative Example 1 will be described below with reference to FIG.

The groove depth H of the main groove G located outside the width direction of the block T4 in Comparative Example 1 is 9 mm. The groove depth of the sipe C is a uniform depth in which the groove depth does not change from one end to the other end in the tire width direction, and the groove depth H3 is the same as the groove depth H3 of the second sipe B in the first embodiment. The sipe width w1 is 0.3 mm (for easy comparison, the sipe groove depth and the sipe width are designated by the same reference numerals as those in the first embodiment).

Then, in Comparative Example 1, as shown in FIG. 4A, all the same sipes C are arranged in a total of 7 rows in the tire circumferential direction in the block T4.

The main difference from each embodiment of the present invention is that the sipe C in Comparative Example 1 has a uniform depth in which the groove depth does not change in the tire width direction in one sipe, and all the sipe C in each row are the same. This is a sipe C of the above, and the groove depth does not change in the tire circumferential direction.

[Comparative Example 2]
Comparative Example 2 will be described below with reference to FIG.

The groove depth H of the main groove G located outside the width direction of the block T5 in Comparative Example 2 is 9 mm. The sipe B has the same groove depth configuration as the second sipe B in the first embodiment, the groove depth H3 in the central region in the tire width direction is 6.5 mm, and the groove depth H4 at both ends in the tire width direction. Is 3.5 mm, and the sipe width w1 is 0.3 mm (for easy comparison, the sipe, the groove depth, and the sipe width are designated by the same reference numerals as those in the first embodiment).

Then, in Comparative Example 2, as shown in FIG. 5A, only the same sipes B are arranged in a total of 7 rows in the tire circumferential direction in the block T5.

The main difference from Example 1 according to the present invention is that the sipe B in Comparative Example 2 has a groove depth that changes in one sipe as in Example 1, but only the same sipe B in each row. It is a sipe that is arranged and the groove depth does not change in the tire circumferential direction.

[Comparative Example 3]
Comparative Example 3 will be described below with reference to FIG.

The groove depth H of the main groove G located outside the width direction of the block T6 in Comparative Example 3 is 9 mm. The sipe C has the same groove configuration as the sipe C in Comparative Example 1, has a uniform groove depth that does not change from one end to the other end in the tire width direction, and the groove depth H3 is the second in Example 1. It is 6.5 mm, which is the same as H3 of the sipe B, and the sipe width w1 is 0.3 mm (for easy comparison, the groove depth and the sipe width are given the same reference numerals as those of Comparative Example 1). The sipe D has a uniform groove depth that does not change from one end to the other end in the tire width direction, and the groove depth H1 is 5.5 mm, which is the same as the groove depth H1 of the first sipe A in the first embodiment. The sipe width w1 is 0.3 mm (for easy comparison, the groove depth and the sipe width are designated by the same reference numerals as those in the first embodiment).

Then, in Comparative Example 3, as shown in FIG. 6A, sipe D is arranged one row at a time on both sides of the block T6 in the tire circumferential direction, and sipe C and sipe D are arranged therein in the tire circumferential direction. It is arranged alternately in. That is, seven rows of sipes are arranged in the order of sipes D, sipes C, sipes D, sipes C, sipes D, sipes C, and sipes D from one side of the block in the tire circumferential direction.

The main difference from Example 1 according to the present invention is that the sipe C and sipe D in Comparative Example 3 are sipe whose groove depth does not change in the tire width direction in any one sipe.

[Comparative test]
Next, with respect to the pneumatic tire according to the present invention, comparative tests were conducted on Examples 1 to 3 and Comparative Examples 1 to 3 described above under the following conditions. The results are shown in Table 1 below.

Test tire size: 195 / 65R15
Test item Ice performance: Each tire was mounted on the vehicle, the vehicle ran at 40 km / h on the ice road surface, stopped from 40 km / h, that is, the braking distance of 0 km was measured. The result of Comparative Example 1 is evaluated by an index of 100, and the larger the index, the better the ice braking performance.

Uneven wear: Each tire was mounted on a vehicle, and the amount of step wear (step between sipes due to wear) when traveling 8000 km on a dry road surface was measured. The result of Comparative Example 1 is evaluated by an index of 100, and the larger the index, the better the result.

[Results of comparative test]
(1) Ice performance Compared to Comparative Example 1 in which only sipes C in which the groove depth does not change are arranged, sipes A, B, A', B'in which the groove depths in the tire width direction and the tire circumferential direction change are used. The ice performance of the arranged Examples 1 to 3 was improved. Probably the change in groove depth at both ends of sipes A, B, A', B'in the tire width direction and the groove depth in the tire central region, and the groove depth of sipes A, B, A', B'in the tire circumferential direction. It is probable that the change improved the land edge effect of the block between each sipe.

In Example 3 in which sipes A'and B'with widened sipes widths at both ends in the tire width direction were arranged, the ice performance was further improved as compared with Example 1. It is considered that the edge effect of the sipe at both ends in the tire width direction was further improved by changing the sipe angle at both ends in the tire width direction of the sipe A'and B'in the tire width direction with respect to the sipe angle in the central region. Be done.

In Example 2 in which a plurality of sipes A are arranged at both ends in the tire circumferential direction, the ice performance is improved as compared with Comparative Example 1, but Example 1 in which sipes A and B are alternately arranged and sipes A'and B'are used. The ice performance was lower than that of Example 3 in which they were alternately arranged. Probably because the change in the edge angle due to the alternating arrangement of sipes with different groove depths has decreased, the edge effect is reduced.

In Comparative Example 2, since the sipe A whose groove depth changes in the tire width direction is arranged, the ice performance is improved as compared with the comparative example 1, but since all the same sipe A are arranged instead of the alternate arrangement. The ice performance is lower than that of Example 1.

In Comparative Example 3, sipes C and D having different groove depths are alternately arranged, but since the groove depth does not change in the tire width direction, the ice performance is lower than that of Comparative Example 1 even in the alternate arrangement. ing.

As described above, in the first to third embodiments, the groove depths H2 of the first sipes A and A'on both sides in the tire circumferential direction at both ends in the tire width direction are set to the groove depths of the second sipes B and B'. Since the tire is deeper than H4, the contact pressure with respect to the road surface is averaged, so that the edge of the sipe is effective and the turning performance is improved, so that the groove depth H3 on both sides in the tire circumferential direction at both ends in the tire width direction works. Does not change in the tire circumferential direction Sipe C in Comparative Example 1 and groove depths H4 on both sides in the tire circumferential direction at both ends in the tire width direction do not change in the tire circumferential direction Sipe B in Comparative Example 2 and both ends in the tire width direction. The ice performance was improved as compared with the sipes C and D of Comparative Example 3 in which sipes D having a groove depth H1 shallower than the groove depth C arranged inward in the tire circumferential direction were arranged on both sides of the tire circumferential direction. The result was.

(2) Suppression of uneven wear Compared to Comparative Example 1 in which only Sipe C whose groove depth does not change is arranged, two types in which the groove depth changes in the tire width direction and the groove depth in the tire circumferential direction differs. In Examples 1 to 3 in which the sipes A, B, A', and B'are arranged, the effect of suppressing uneven wear was improved. Probably, the groove depth of sipes A, B, A', B'changes in the tire width direction, and the groove depth also differs in the tire circumferential direction, so that the rigidity of the tire is dispersed and the local rigidity difference is eliminated. It is probable that this was due to the fact that

In Example 1 in which sipes A and B were alternately arranged, the effect of suppressing uneven wear was improved as compared with Example 2 in which a plurality of sipes A were arranged on both sides in the tire circumferential direction. Probably because the alternating arrangement of sipes A and B made it possible to further disperse the rigidity of the tire and eliminate the local rigidity difference as compared with Example 2 in which a plurality of sipes A were arranged on both sides in the tire circumferential direction. It is considered to be.

In Example 3 in which sipe A'and B'with widened sipe widths at both ends in the tire width direction were alternately arranged, the effect of suppressing uneven wear was improved as compared with Example 1 in which sipe A and B were alternately arranged. Probably because the sipe width at both ends in the tire width direction was widened, the rigidity in the tire circumferential direction at both ends in the tire width direction of the block decreased, so that the difference in rigidity from the central region became smaller, and the overall rigidity of the tire became even higher. It is considered that this is because the tires were dispersed and the local rigidity difference could be eliminated.

In Comparative Example 2, both ends in the tire width direction are shallow and only the sipe A having a deep central region is arranged, so that the rigidity of both ends of the block in the tire circumferential direction is high and the rigidity of the block central region is low, so that it is local. Due to the difference in rigidity, the effect of suppressing uneven wear was lower than that of Comparative Example 1.

In Comparative Example 3, by alternately arranging two types of sipes C and D having different groove depths, the dispersibility of rigidity is improved and the effect of suppressing uneven wear is improved as compared with Comparative Example 1. Since the groove depth in the width direction has not changed, the tire rigidity is not dispersed and a local rigidity difference occurs in the tire width direction, so that the effect of suppressing uneven wear is lower than in Example 1.

Further, as in Examples 1 to 3, the groove depths H2 of the first sipes A and A'on both sides in the tire circumferential direction at both ends in the tire width direction are set from the groove depths H4 of the second sipes B and B'. It is considered that one of the factors for suppressing uneven wear is that the contact pressure with respect to the road surface is averaged and the turning performance is improved.

From the above test results, it was found that Examples 1 to 3 achieved both ice performance and suppression of uneven wear, and Comparative Examples 1 to 3 were carried out in either ice performance or suppression of uneven wear. It was found to be lower than in Examples 1 to 3, and it was found that both ice performance and suppression of uneven wear could not be achieved.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

T, T1, T2, T3, T4, T5, T6 ... Blocks A, B, A', B', C, D ... Sipe H1, H2, H3, H4 ... Sipe groove depth G・ ・ ・ Main groove depth w1, w2 ・ ・ ・ Sipe width

Claims (4)

A plurality of sipes extending in the tire width direction and opening at both ends are formed in the tread portion of the block formed in the tire tread portion and divided by a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction. Has been formed and
The plurality of sipes consist of a first sipe and a second sipe.
In both the first sipe and the second sipe, the groove depth in the central region in the tire width direction is deeper than the groove depth in both ends in the tire width direction.
The groove depth of the tire width direction central region of the first sipe is shallower than the groove depth of the tire width direction central region of the second sipe, and both ends of the first sipe in the tire width direction The groove depth is deeper than the groove depth at both ends of the second sipe in the tire width direction.
The second sipe is formed so that the groove depth in the central region in the tire width direction is shallower than the groove depth of the main groove that partitions the block.
The first sipe is a pneumatic tire characterized in that the first sipes are arranged on both sides of the block in the circumferential direction of the tire. The pneumatic tire according to claim 1, wherein in the block, the first sipe and the second sipe are alternately arranged in the tire circumferential direction. The pneumatic tire according to claim 1, wherein a plurality of first sipes are arranged on both sides in the tire circumferential direction in the block, and a second sipes are arranged in a central region in the tire circumferential direction. The first sipe and the second sipe are characterized in that the sipe width in the tire circumferential direction gradually widens in a range of 1.5 to 3 times from the central region in the tire width direction to both ends. The pneumatic tire according to any one of claims 1 to 3.

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