JP2009006770A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of suppressing a crack growing toward the center of a land part from a sipe. <P>SOLUTION: A pneumatic tire 1 includes a second rib, a shoulder rib and a center rib formed of an inside main groove and outside main groove in a tread part, and a sipe 120 and a circumferential sipe 121 in each rib (land part), wherein both ends (first circumferential sipe start end 1C and first circumferential sipe terminal end 1D)of the circumferential sipe 121 are disposed on the center line CL side from ends (first sipe end 1A, second sipe end 1B) on the most center line CL side of the sipe 120. In this way, the crack can be suppressed which is generated from the ends (first sipe end 1A, second sipe end 1B) on the most center line CL side of the sipe 120 and grown toward a tire width direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that suppresses cracks (hereinafter referred to as cracks) generated from sipes and growing in the tire width direction.

  Conventionally, in a heavy duty pneumatic tire having a rib / block (hereinafter referred to as a land portion) formed by a main groove and mounted on a steering shaft, a short interval in the tire circumferential direction is used to suppress uneven wear of the land portion. In some cases, a plurality of sipes are arranged at the edge of the land. For example, in Patent Document 1, a plurality of sipes are formed in the tire circumferential direction along the tire circumferential direction on the tire circumferential main groove sidewall surface of the rib, with one end opening in the tire circumferential main groove and the other end terminating in the rib. Thus, a technique is disclosed in which the rigidity of the rib in the vicinity of the edge portion is reduced to suppress the occurrence of rib tears (breakage such as baldness) and the uneven wear of the rib end.

JP 2003-63212 A, paragraph number 0050

  FIG. 7 is a diagram showing a crack generated from an end portion of a sipe in a conventional pneumatic tire. In the technique disclosed in Patent Document 1, when a vehicle equipped with a pneumatic tire 5 rides on a curbstone, a crack C is generated from the sipe end 5A on the land portion center side of the sipe 520 provided on the edge portion of the land portion. And the crack C grows from the sipe end 5A toward the center of the land. Then, this invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can suppress the crack which grows from the sipe toward the land center.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention includes a land portion formed by being partitioned by a main groove in a cap tread portion, and a tire circumferential direction at an edge portion of the land portion. A plurality of sipes arranged side by side, and a starting point closer to the center of the land than the first part located at the most center in the tire width direction of the land of the first sipe that is one of the sipes And a sipe in a circumferential direction having an end point on the center side of the land portion with respect to the second portion located closest to the center side in the tire width direction of the land portion of the land portion of the second sipe adjacent to the first sipe And the starting point and the ending point are a first line that passes through the first part and is parallel to the tire width direction, and a second line that passes through the second part and is parallel to the tire width direction, Of the land sectioned by Sites 1 and said second portion, characterized in that provided in the land portion can be connected by the shortest distance.

  The pneumatic tire according to the present invention has a starting point of the circumferential sipe in the land portion closer to the center of the land than the first portion closest to the center of the land of the first sipe, and is adjacent to the first sipe. The end point of the circumferential sipe is located in the land portion closer to the center of the land than the second part closest to the center of the land of the second sipe. Thereby, while generating from the site | part (1st site | part, 2nd site | part) of the most land part center side of a sipe, the crack which grows toward a center line can be suppressed.

  As a preferred aspect of the present invention, a line connecting the first part and the starting point has an angle in a range of 20 degrees to 70 degrees with respect to the first line, and the second part and It is desirable that the line connecting the end point has an angle in the range of 20 degrees to 70 degrees with respect to the second line.

  As a preferable aspect of the present invention, the distance between the start point and the straight line connecting the first part and the second part, and the distance between the end point and the straight line connecting the first part and the second part. Is preferably in the range of 2.0 mm to 5.0 mm.

  As a preferred aspect of the present invention, the circumferential sipe is formed in a curved shape in the cap tread portion, and a tangent line at a start point and an end point of the circumferential sipe is −45 degrees with respect to a line parallel to the tire circumferential direction. It is desirable to have an angle in the range of 45 degrees or more.

  As a preferred aspect of the present invention, it is desirable that the circumferential sipe has a depth in the tire radial direction of 50% or more and 100% or less with respect to a depth of the sipe in the tire radial direction.

  The pneumatic tire according to the present invention can suppress cracks growing from sipe toward the center of the land.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a pneumatic tire according to the first embodiment. In addition, although the pneumatic tire 1 which concerns on this embodiment is demonstrated as a heavy load tire used for a truck, a bus, etc., it is not limited to this. As shown in FIG. 1, the pneumatic tire 1 according to this embodiment includes a tread portion TR and sidewall portions SI and bead portions BE on both sides thereof. Further, the pneumatic tire 1 has a carcass 11 and a belt layer 12.

  The carcass 11 is formed of a fiber coated with rubber or a cord layer formed of steel, and forms a skeleton of the pneumatic tire 1. The carcass 11 is stretched over the bead core 14 of the bead part BE from both sides of the tread part TR via the sidewall part SI. The carcass 11 serves as a pressure vessel when the pneumatic tire 1 is filled with air and supports a load applied to the pneumatic tire 1 by its internal pressure.

  The belt layer 12 is provided on the outer periphery in the tire radial direction than the carcass 11 in the tread portion TR. The belt layer 12 is a reinforcing layer provided in the circumferential direction of the carcass 11 and applies a tightening force to the carcass 11 to increase the rigidity of the tread portion TR, and at the time of traveling of the vehicle on which the pneumatic tire 1 is mounted. The shock is mitigated and the trauma generated in the tread portion TR is prevented from reaching the carcass 11.

  The tread portion TR includes an under tread 15, a cap tread 16, a main groove 17, and a rib 18. The under tread 15 is provided on the outer peripheral side in the tire radial direction from the belt layer 12. The cap tread 16 is provided on the outer periphery in the tire radial direction than the under tread 15. A tread surface is formed on the outer peripheral surface of the cap tread 16, that is, the surface that contacts the road surface during traveling. Furthermore, an inner main groove 17a and an outer main groove 17b are formed on the tread surface along the tire circumferential direction. Thereby, a plurality of ribs 18 as land portions are formed in the tread portion TR by the inner main groove 17a and the outer main groove 17b.

  The sidewall portion SI has a side tread 19. The side tread 19 prevents trauma generated in the sidewall portion SI from reaching the carcass 11.

  The bead portion BE includes a bead core 14 and a bead filler 14a. The bead core 14 is formed by winding a bead wire 14b, which is a steel wire, in a ring shape. The bead core 14 supports the tension of the carcass 11 generated by the internal pressure of the pneumatic tire 1.

  The bead filler 14 a is disposed in a space formed by the carcass 11 and the bead core 14. Specifically, the bead filler 14 a is disposed in a space formed by the carcass 11 before being folded, the bead core 14, and the carcass 11 after being folded when the carcass 11 is folded at the bead core 14. The bead filler 14a fixes the carcass 11 to the bead core 14 and adjusts the shape of the bead portion BE. Furthermore, the bead filler 14a increases the rigidity of the bead portion BE.

  FIG. 2 is a plan view of the tread portion of the pneumatic tire according to the first embodiment, and FIG. 3 is a plan view in which the vicinity of the sipe according to the first embodiment is enlarged. Unless otherwise noted, the plan view means a view when the tread portion TR that is the circumferential surface of the pneumatic tire 1 is developed on a plane. The equator line SL is a center line in the tire width direction, and the direction away from the equator line SL is defined as the outer side, and the direction toward the equator line SL is defined as the inner side. The tread portion TR of the pneumatic tire 1 according to the present embodiment includes a center rib 18a, a second rib 18b, a shoulder rib 18c, an inner main groove 17a, an outer main groove 17b, a sipe 120, and a circumferential sipe 121. And having.

  The center rib 18a is a land portion formed by the two inner main grooves 17a. A center line CL in the tire width direction of the center rib 18a (a center line in the tire width direction of each rib 18 is referred to as a center line CL) coincides with the equator line SL. Further, the second rib 18b is formed by the outer main groove 17b and the inner main groove 17a located outside the inner main groove 17a. Further, a shoulder rib 18c is formed on the outer side of the second rib 18b by the outer main groove 17b.

  The sipe 120 has tires on the outer edge and the inner edge of the shoulder rib 18c in the tire width direction, that is, in the vicinity of the outer main groove 17b and the edge near the shoulder rib 18c, which is a portion far from the equator line SL (see FIG. 2). A plurality are provided along the circumferential direction. As a result, the rigidity in the vicinity of the edge portion of the rib 18 is reduced, so that uneven wear of the shoulder rib 18c that is most likely to cause uneven wear can be suppressed. Furthermore, the sipe 120 is also provided at the edge portion of the center rib 18a and the edge portion of the second rib 18b. Note that the sipe 120 is a sipe having one end opened on the inner main groove 17a or the outer main groove 17b or the side surface of the shoulder portion.

  The sipes 120 are preferably provided at intervals of about 3.0 mm to 5.0 mm. Furthermore, in the pneumatic tire 1 according to the present embodiment, the sipe 120 is provided at the edge portion of all the ribs 18, but it is sufficient that the sipe 120 is provided at at least one edge portion.

  In FIG. 3, the plurality of sipes 120 have the same shape without individual differences, but for convenience of explanation, the sipe 120 includes a first sipe 120a and a second sipe 120b adjacent to the first sipe 120a. It is assumed that it is configured. Similarly, the circumferential sipe 121 is described as including a first circumferential sipe 121a and a second circumferential sipe 121b adjacent to the first circumferential sipe 121a.

  The circumferential sipe 121 is a sipe provided along the tire circumferential direction, and is a sipe having a depth equivalent to that of the sipe 120. Unless otherwise noted, the depth means the length in the tire radial direction, that is, the length in the thickness direction of the tread portion TR. In addition, the circumferential sipe 121 according to the present embodiment has a depth equivalent to that of the sipe 120, but the depth can be appropriately changed within a range of 50% to 100% of the depth of the sipe 120. If the depth of the circumferential sipe 121 is 50% or more of the depth of the sipe 120, the depth of the circumferential sipe 121 disappears earlier than the sipe 120 is consumed when the wear of the tread portion TR advances. It can be suppressed from disappearing. Moreover, if the depth of the circumferential sipe 121 is 100% or less of the depth of the sipe 120, an excessive strength reduction of the rib 18 can be suppressed. That is, it is preferable that the depth of the circumferential sipe 121 is set within a range in which the sipe 120 and the circumferential sipe 121 disappear or lose their functions at the same time when the wear of the tread portion TR progresses.

  As shown in FIG. 3, the end of the first sipe 120a closest to the center line CL is defined as a first sipe end 1A. The end of the second sipe 120b closest to the center line CL is defined as a second sipe end 1B. The first circumferential sipe 121a is a closed sipe, and has a first circumferential sipe starting end 1C at an end portion on the first sipe 120a side and a first circumferential sipe terminating end 1D at an end portion on the second sipe 120b side. The second circumferential sipe 121b has a second circumferential sipe starting end 1E at the end on the second sipe 120b side. Unless otherwise specified, these end portions refer to a point where the center line and the groove wall in the width direction of the sipe groove intersect for the sake of convenience. Further, the first circumferential sipe starting end 1C, the first circumferential sipe terminating end 1D, and the second circumferential sipe starting end 1E according to the present embodiment correspond to a starting point and an ending point in the claims.

  In FIG. 3, for convenience of explanation, a straight line passing through the first sipe end 1A and parallel to the tire width direction is a line L11, and a straight line passing through the second sipe end 1B and parallel to the tire width direction is a line L12. The line segment connecting the portion 1A and the first circumferential sipe start end 1C is a line L13, and the line segment connecting the second sipe end portion 1B and the first circumferential sipe end 1D is a line L14, the first sipe end portion 1A and the second sipe. A straight line passing through the end 1B is a line L15, a narrow angle formed by the line L11 and the line L13 is an angle θ11, and a narrow angle formed by the line L12 and the line L14 is an angle θ12. In FIG. 3, lines L11 to L15 are indicated by broken lines.

  The first circumferential sipe starting end 1C and the first circumferential sipe terminating end 1D are provided in the tread portion TR (see FIG. 1) on the center line CL side with respect to the line L15. Specifically, the first circumferential sipe starting end 1C is 2.0 mm away from the line L15 (distance D11 in FIG. 3) on the tread portion TR on the center line CL side, and the first circumferential sipe terminating end 1D is 2 from the line L15. Provided in the tread portion TR on the center line CL side that is 0.0 mm apart (distance D12 in FIG. 3). The first circumferential sipe starting end 1C and the first circumferential sipe terminating end 1D according to the present embodiment are provided at a distance of 2.0 mm from the line L15, but may be in a range of 2.0 mm to 5.0 mm. . If the distance between the first circumferential sipe start end 1C and the first circumferential sipe end 1D and the line L15 is 2.0 mm or more, the distance between the first sipe end 1A and the first circumferential sipe start end 1C and the second sipe The distance between the first sipe end 1A and the first circumferential sipe start end 1C or the second sipe end 1B and the first circumferential direction due to a decrease in the distance between the end 1B and the first circumferential sipe end 1D. It is possible to suppress a decrease in strength of the land portion between the sipe end 1D. On the other hand, if the distance between the first circumferential sipe starting end 1C and the first circumferential sipe terminating end 1D and the line L15 is 5.0 mm or less, the crack C generated from the first sipe end 1A or the second sipe end 1B. The growth toward the center line CL can be suppressed early.

  For example, the angle θ11 and the angle θ12 are set to 30 degrees. Note that the angle θ11 and the angle θ12 according to the present embodiment are set to 30 degrees, but may be in the range of 20 degrees to 70 degrees. Further, the angle θ11 and the angle θ12 may not be the same angle. If the angle θ11 and the angle θ12 are 20 degrees or more, the distance between the first circumferential sipe end 1D of the first circumferential sipe 121a and the second circumferential sipe starting end 1E of the second circumferential sipe 121b becomes small. Accordingly, the strength reduction of the rib 18 between the first circumferential sipe end 1D and the second circumferential sipe starting end 1E can be suppressed. On the other hand, if the angle θ11 and the angle θ12 are 70 degrees or less, the crack C generated from the second sipe end 1B passes between the first circumferential sipe end 1D and the second circumferential sipe start 1E. The possibility of growing toward the center line CL can be suppressed. More preferably, if the angle θ11 and the angle θ12 are set in the range of 30 degrees or more and 60 degrees or less, the strength of the land portion is reduced between the first circumferential sipe end 1D and the second circumferential sipe start end 1E. It is possible to achieve both suppression and suppression of the crack C growing toward the center line CL.

  In the present embodiment, the crack C generated from the second sipe end 1B grows toward the center line CL. At this time, the crack C grows in the direction of about 45 degrees with the line L12. As the growth of the crack C proceeds, the crack C reaches the first circumferential sipe 121a or the second circumferential sipe 121b and opens in the groove of each circumferential sipe 121. Thereby, the growth toward the tire width direction of the crack C generated from the first sipe end 1A can be suppressed. Similarly, also in the crack C generated from the second sipe end 1B, the growth of the crack C in the tire width direction can be suppressed.

  FIG. 4 is an enlarged plan view showing the vicinity of a circumferential sipe according to a modification of the first embodiment. In addition, about the structure, effect | action, and effect which are common in Embodiment 1, the overlapping description is abbreviate | omitted and the same code | symbol is attached | subjected.

  As shown in FIG. 4, the sipe 120 of the pneumatic tire 2 includes a first sipe 120a and a second sipe 120b having a different length from the first sipe 120a, and the first sipe 120a and the second sipe. 120b may be alternately arranged.

  For example, the difference between the length of the first sipe 120a and the length of the second sipe 120b is set so that the angle θ23 is 15 degrees. The difference between the length of the first sipe 120a and the length of the second sipe 120b according to the present embodiment is set so that the angle θ23 is 15 degrees, but the angle θ23 is greater than −20 degrees and less than 20 degrees. (The angle θ23 = 0 ° is the first embodiment). Note that, unless otherwise specified, + − attached to an angle indicates that one side of a reference line (in this case, the center line CL) is + and the other side is − between two straight lines forming the angle.

  FIG. 5 is an enlarged plan view of the vicinity of a sipe according to a modification of the first embodiment. As shown in FIG. 5, the pneumatic tire 3 according to the modification of the present embodiment is different from the sipe according to the above-described embodiment in the difference between the length of the first sipe 120a and the length of the second sipe 120b. A sipe 120 having an angle θ23 set to 50 degrees may be provided, and a circumferential sipe 121 configured in a curved manner may be provided in the vicinity of the sipe 120. In addition, about the structure, effect | action, and effect which are common in the above-mentioned embodiment, the overlapping description is abbreviate | omitted and the same code | symbol is attached | subjected.

  For example, the difference between the length of the first sipe 120a and the length of the second sipe 120b is set so that the angle θ23 is 50 degrees. The difference between the length of the first sipe 120a and the length of the second sipe 120b according to the present embodiment is set so that the angle θ23 is 50 degrees, but the angle θ23 is greater than −90 degrees and less than 90 degrees. It is sufficient that the difference is an angle in the range.

  For example, the angle θ34 and the angle θ35 are set to 10 degrees. The angle θ34 according to the present embodiment is set to 15 degrees, but may be in the range of −45 degrees to 45 degrees. Further, the circumferential sipe 121 is formed in a substantially S shape. The circumferential sipe 121 according to the present embodiment may have a shape other than a substantially S shape, or may be a free curve.

  In the present embodiment, the distance D11 and the distance D12 are the same distance, but the distance D11 and the distance D12 may be set to different distances. At this time, it is preferable to set the angle θ34 and the angle θ35 to be larger than −45 degrees and smaller than 45 degrees. Thereby, generation | occurrence | production of the crack newly generated from the both ends (1st circumferential sipe starting end 1C, 1st circumferential sipe starting end 1D, 2nd circumferential sipe starting end 1E) of the circumferential sipe 121 can be suppressed.

  In the pneumatic tire 3 according to the present embodiment, the circumferential sipe 121 is formed in a curved shape in the tread portion TR, and a line L36 that is a tangent line at the first circumferential sipe starting end 1C of the circumferential sipe 121 and the circumferential sipe. A line L37 that is a tangent to the first circumferential sipe end 121 of the first circumferential direction has an angle in a range of −45 degrees to 45 degrees with respect to a center line CL that is a line parallel to the tire circumferential direction.

  With the above configuration, the pneumatic tire 3 according to the present embodiment is configured even when the sipe 120 includes the first sipe 120a and the second sipe 120b having different lengths in a range satisfying −90 <angle θ23 <90. The occurrence of cracks newly generated from the end of the circumferential sipe 121 can be suppressed while producing the same effect as that of the pneumatic tire according to the above-described embodiment. Moreover, since the circumferential sipe is provided in a curved shape, it can be flexibly handled by changing the design of the tread portion TR.

  FIG. 6 is an enlarged plan view of the vicinity of a sipe according to a modification of the first embodiment. As shown in FIG. 6, the pneumatic tire 4 according to the modification of the present embodiment may include a sipe 120 having an inclination with respect to the center line CL, instead of the sipe according to the above-described embodiment. In addition, about the structure, effect | action, and effect which are common in the above-mentioned embodiment, the overlapping description is abbreviate | omitted and the same code | symbol is attached | subjected.

Table 1 is a table showing results of running experiments in which the uneven wear resistance and crack resistance of the pneumatic tire according to Example 1 were examined. The size of the pneumatic tire according to each example used in the running test is common to 295 / 80R22.5. Further, in this embodiment, each pneumatic tire is mounted on a 2-D4 vehicle via a JATMA standard rim, and a running experiment is performed with the maximum air pressure and maximum load specified by JATMA.

  Note that the pneumatic tire according to Experimental Example 1 to Experimental Example 6 is the same as the pneumatic tire 1 according to the first embodiment, in which the sipe is formed at the edge of the shoulder rib 18c on the inner side in the tire width direction and the second rib 18b on the outer side in the tire width direction. 120 and a circumferential sipe 121 were provided. In providing the circumferential sipe 121, the angle θ11 (= angle θ12) and the depth ratio of the circumferential sipe 121 to the depth of the sipe 120 were varied. In the pneumatic tires according to Experimental Example 1 to Experimental Example 6, as a common setting, the first circumferential sipe starting end 1C, the first sipe end 1A, and the second sipe end 1B, which are the starting points of the circumferential sipe 121, are used. The distance D11 between the first sipe end 1D, which is the end point of the circumferential sipe 121, and the straight line connecting the first sipe end 1A and the second sipe end 1B is 3 mm. 0.0 mm. Further, in the pneumatic tire according to the conventional example, only the sipe was provided at the edge portion, similarly to the pneumatic tire according to Experimental Example 1 to Experimental Example 6.

  In Table 1, the uneven wear resistance performance is obtained by relatively evaluating the uneven wear amount generated in the pneumatic tire according to each experimental example, where the uneven wear amount generated in the pneumatic tire in the conventional example is 100. At this time, the larger the value shown in Table 1, the better the uneven wear resistance performance. The running test of uneven wear resistance performance was performed by running 60,000 km at a predetermined course at 80 km / h and measuring the amount of uneven wear generated on the shoulder rib after running. The crack resistance performance is a relative evaluation of the number of cracks generated in the pneumatic tire according to each experimental example, with the number of cracks generated in the pneumatic tire of the conventional example being 100. At this time, the larger the value shown in Table 1, the better the crack resistance performance. In addition, the running experiment of the crack resistance performance was performed by repeating the entry and exit of a vehicle equipped with each pneumatic tire at a predetermined angle 10 times with respect to the step provided in the course.

  In the pneumatic tire according to any of the experimental examples, both the uneven wear resistance and the crack resistance performance are improved as compared with the pneumatic tire in the conventional example. In particular, the running test results of the pneumatic tires according to Experimental Example 3, Experimental Example 4, and Experimental Example 5 were good. That is, if the angle θ11 (angle θ12) is set in the range of 20 degrees or more and 70 degrees or less, the uneven wear resistance performance and crack resistance performance of the pneumatic tire are the same as those of the conventional pneumatic tire. Improved than crack performance. In particular, the running test results of the pneumatic tires according to Experimental Example 3, Experimental Example 4, and Experimental Example 5 are better than those of the pneumatic tires according to Experimental Example 1, Experimental Example 2, and Experimental Example 6. there were. From this result, it can be seen that the angle θ11 (angle θ12) is more preferably set in the range of 30 degrees or more and 60 degrees or less. Further, if the depth ratio of the circumferential sipe 121 to the depth of the sipe 120 is set in a range of 50% or more and 100% or less, the uneven wear resistance and the crack resistance performance of the pneumatic tire are the same as the conventional pneumatic. This improves the uneven wear resistance and crack resistance of the tire. Further, the depth ratio of the circumferential sipe 121 to the depth of the sipe 120 is more preferably set in a range of 70% or more and 100% or less.

  As described above, the pneumatic tire according to the present invention is useful as a pneumatic tire that can suppress the crack C growing from the sipe toward the center of the land portion.

1 is a cross-sectional view of a pneumatic tire according to Embodiment 1. FIG. 3 is a plan view of a tread portion of the pneumatic tire according to Embodiment 1. FIG. It is the top view which expanded and displayed the sipe vicinity which concerns on Embodiment 1. FIG. FIG. 9 is a plan view showing an enlarged vicinity of a sipe according to a modification of the first embodiment. FIG. 9 is a plan view showing an enlarged vicinity of a sipe according to a modification of the first embodiment. FIG. 9 is a plan view showing an enlarged vicinity of a sipe according to a modification of the first embodiment. It is a figure which shows the crack which generate | occur | produces from the edge part of the sipe in the conventional pneumatic tire.

Explanation of symbols

1, 2, 3, 4, 5 Pneumatic tire 11 Carcass 12 Belt layer 14 Bead core 14a Bead filler 14b Bead wire 15 Under tread 16 Cap tread 17 Main groove 17a Inner main groove 17b Outer main groove 18 Rib 18a Center rib 18b Second rib 18c Shoulder Rib 19 Side tread 120 Sipe 120a First sipe 120b Second sipe 121 Circumferential sipe 121a First circumferential sipe 121b Second circumferential sipe 1A First sipe end 1B Second sipe end 1C First circumferential sipe start 1D 1st circumferential sipe end 1E 2nd circumferential sipe start 520 sipe 5A sipe end C crack TR tread part SI sidewall part BE bead part SL equatorial line CL center line D11 distance D12 distance D21 distance L11 to L15 line L36 line L37 line θ11 angle θ12 angle θ23 angle θ34 angle θ35 angle

Claims (5)

A land portion formed by being separated by a main groove in the cap tread portion;
A sipe provided in a plurality in the tire circumferential direction at the edge portion of the land portion,
The first sipe, which is one of the sipe, has a starting point on the center side of the land portion rather than the first portion located on the most central side in the tire width direction of the land portion, and the first sipe A circumferential sipe having an end point on the center side of the land portion relative to the second portion located on the most central side in the tire width direction of the land portion of the second sipe adjacent to the sipe;
With
The start point and the end point are land defined by a first line passing through the first part and parallel to the tire width direction, and a second line passing through the second part and parallel to the tire width direction. A pneumatic tire characterized in that the pneumatic tire is provided on a land portion that can connect the first portion and the second portion with a shortest distance.   The line connecting the first part and the start point has an angle in the range of 20 degrees to 70 degrees with respect to the first line, and the line connecting the second part and the end point is 2. The pneumatic tire according to claim 1, wherein the pneumatic tire has an angle in a range of 20 degrees to 70 degrees with respect to the second line.   The distance between the start point and the straight line connecting the first part and the second part and the distance between the end point and the straight line connecting the first part and the second part are 2.0 mm or more and 5 respectively. The pneumatic tire according to claim 1 or 2, wherein the range is 0.0 mm or less.   The circumferential sipe is formed in a curved shape in the cap tread portion, and a tangent line at a start point and an end point of the circumferential sipe is an angle in a range of −45 degrees to 45 degrees with respect to a line parallel to the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 3, characterized by comprising:   The circumferential sipe has a depth in the tire radial direction of 50% or more and 100% or less with respect to a depth of the sipe in a tire radial direction. Pneumatic tire described in 2.

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