JP5947532B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which at least one circumferential groove extending along a tire circumferential direction is provided in a tread portion, and a land portion is partitioned in the tread portion. The present invention relates to an apparatus for suppressing uneven wear occurring at a side end.

  Conventionally, in a pneumatic tire, in order to suppress uneven wear and improve wet performance, as shown in FIGS. 8 and 9, the circumferential groove of the rib-shaped or block-shaped land portion 3 partitioned by the circumferential groove 2 is used. A plurality of sipes (so-called multi-sipes) 4 having one end in the tire width direction opening in the circumferential groove 2 and the other end terminating in the land portion 3 are arranged in the tire circumferential direction. Are arranged at intervals (see, for example, Patent Document 1). By arranging such a sipe 4 at the side end portion 3a of the land portion 3, an increase in local ground pressure to the side end portion 3a when a lateral force is input can be reduced. 3 can suppress uneven wear at the side end portions 3a and improve the wet performance by increasing the edge component.

JP 2002-362115 A

  However, in the pneumatic tire provided with the sipe as described above, the schematic diagram of FIG. 10A (in the figure, the phantom line indicates the sipe 4 during grounding and before kicking out, and the solid line indicates the sipe after kicking out. As will be described with reference to FIG. 4, the portion of the side end 3 a of the land portion 3 adjacent to the sipe 4 is easy to move when the tire rolls (that is, the amount of variation is large), and when the tire is kicked out Since a large shear strain is generated in the portion, the sipe 4 of the side portion 3a of the land portion 3 is shown in a plan view of the portion shown in the schematic diagram of FIG. In view of this, there is a problem that the portion on the traveling direction side of the tire (indicated by the slanted line in the figure) is subject to uneven wear, and the uneven wear cannot be sufficiently suppressed. In FIGS. 10A and 10B, the symbol I indicates the tire rotation direction, and the symbol R indicates the tire radial direction.

  Further, due to the weight, rigidity, dimensional variations, etc. that are inevitably generated in the manufacture of the tire, as shown in the schematic diagram of the tire side portion in FIG. 11, the side end of the land portion where the sipe is formed is shown. Wear progresses early in an unspecified part of the part, that is, a part with a fast wear rate and a part with a slow wear may be mixed over the circumference at the side end of the land. Such uneven uneven wear on the circumference of the tire not only causes poor appearance but also causes vibration and noise.

  Therefore, an object of the present invention is to sufficiently suppress the uneven wear of the side portion adjacent to the circumferential groove of the land portion partitioned by the circumferential groove, and on the circumference at the side end portion. It is an object of the present invention to provide a pneumatic tire that can suppress uneven wear.

The present invention has been made in order to solve the above-described problems. In the pneumatic tire according to the present invention, the rotation direction of the tire is specified, and at least one of the pneumatic tires extends along the tire circumferential direction in the tread portion. A plurality of sipes having one end in the tire width direction opened in the circumferential groove at a lateral end adjacent to the circumferential groove. In the pneumatic tire formed in the direction spaced apart from each other, the sipe is a cross-section along a plane parallel to the tire equatorial plane, with the outer end in the tire radial direction opening on the land surface as a reference, The extending direction from the outer end toward the inner end in the tire radial direction is inclined in a direction opposite to the rotation direction of the tire with respect to the normal of the land surface, and the inclination angle of the sipe with respect to the normal Is the outer end in the tire radial direction Become large toward the inner end of al the tire radial direction, and Ri inclination angle der 10 ° or more with respect to the normal line from the outer end of the tire radial direction, wherein the sipe is outside the tire radial direction There are two bent portions between the end and the inner end in the tire radial direction, and the inclination angle changes through the bent portion . Here, “the inclination angle of the sipe with respect to the normal increases from the outer end in the tire radial direction toward the inner end in the tire radial direction” means that the sipe inclination angle continuously increases. It means not only things but also increasing in stages.

  In the pneumatic tire according to the present invention, when viewed in a cross section parallel to the tire equatorial plane, the sipe is based on the outer end in the tire radial direction, and the extending direction is opposite to the rotational direction of the tire (i.e., Since the slope is inclined in the direction opposite to the direction in which the shearing force is applied), the amount of fluctuation of the portion adjacent to the sipe at the side end of the land during rolling of the tire can be reduced. It is possible to reduce uneven wear occurring at the side end portion of the tire in the traveling direction side when viewed from the sipe. In addition, when a part with a fast wear rate and a slow part are generated on the side edge of the land part, the inclination angle of the sipe with the fast wear rate with respect to the normal is the sipe with the slow wear rate. However, the wear rate on the circumference is made uniform because the portion with a larger wear angle with respect to the normal line and the portion with a fast wear rate is less likely to wear than the portion with a slow wear rate.

In the pneumatic tire of the present invention, the sipe has two bent portions between an outer end in the tire radial direction and an inner end in the tire radial direction, and the inclination angle is It changes through the bent portion. According to this, when the portion facing the side portion of the land portion through the sipe is deformed at the time of ground contact, the opposing wall surfaces of the sipe forming the bent portion can be engaged with each other. The uneven wear can be further suppressed by increasing the rigidity of the portion.

  In the pneumatic tire of the present invention, it is preferable that the sipe has two bent portions. According to this, the effect of equalizing the wear rate on the circumference can be obtained twice, from the initial stage of wear to the middle stage of wear and from the middle stage of wear to the last stage of wear, and the effect on the circumference over a longer period can be obtained. Uniform wear can be suppressed.

Furthermore, in the pneumatic tire of the present invention, of the two bent portions, the one closer to the land surface is the first bent portion, the one far from the land portion surface is the second bent portion, The angle of inclination of the sipe with respect to the normal line segment connecting the outer end of the tire in the radial direction of the tire and the first bent portion is α, and the first bent portion and the second bent portion of the sipe are connected. When the inclination angle with respect to the normal of the line segment is β, and the inclination angle of the sipe with respect to the normal of the line segment connecting the second bent portion and the inner end in the tire radial direction is γ, Each inclination angle α, β and γ preferably satisfies 10 ° ≦ α ≦ 30 ° and 15 ° ≦ β ≦ 60 ° and 30 ° ≦ γ ≦ 75 °. According to this, the effect which suppresses uneven wear and the effect which makes a wear rate uniform on the periphery can be acquired more reliably.

  Furthermore, in the pneumatic tire according to the present invention, a distance along the tire circumferential direction between the outer ends in the tire radial direction of the sipes adjacent in the tire circumferential direction is L1, and the tire diameter of the sipe is When the distance along the tire circumferential direction between the outer end in the direction and the inner end in the tire radial direction is L2, it is preferable that the distances L1 and L2 satisfy L1> L2. When the sipes are close to each other, the part adjacent to the sipe is likely to be deformed and the wear is likely to progress.On the other hand, by setting the distance between the sipes to a predetermined value or more, deformation of the part between the sipes is suppressed. This is because the progress of wear can be delayed.

  Moreover, in the pneumatic tire of the present invention, of the two bent portions, the one closer to the land surface is the first bent portion, and the one far from the land surface is the second bent portion, The distance along the normal line from the outer end in the tire radial direction of the sipe to the first bent portion is D1, and the distance from the first bent portion to the second bent portion of the sipe is the normal line. The distance along the normal line from the second bent portion of the sipe to the inner end in the tire radial direction is D3, and the distance from the outer end of the sipe in the tire radial direction is D2. When the distance along the normal line to the inner end in the tire radial direction is D4, the distances D1, D2, and D3 are (D4 × 1/4) ≦ D1 ≦ (D4 × 1/2) and (D4 × 1/4) ≦ D2 ≦ (D4 × 1/2) and (D4 × 1/4) ≦ D3 ≦ (D4 × 1 / ) Is preferably satisfied. According to this, it is possible to enhance the effect of suppressing uneven wear in the early and middle periods of wear, and the wear rate on the circumference can be made uniform.

  According to the pneumatic tire of the present invention, the uneven wear of the side end adjacent to the circumferential groove of the land portion partitioned by the circumferential groove is sufficiently suppressed, and the circumferential edge at the side end is increased. It is possible to suppress non-uniform wear in the case.

It is an expanded view showing a part of a tread portion of a pneumatic tire of one embodiment according to the present invention. It is sectional drawing which follows the AA line in FIG. (A) is sectional drawing which shows typically the mode before kicking out (during ground contact) and after kicking out of the sipe provided in the side edge part of a land part in the pneumatic tire of FIG. (B) is a top view which shows typically the mode of the partial wear which generate | occur | produces in the side edge part of a land part in the pneumatic tire of FIG. (A) is sectional drawing which shows a part with a slow wear rate on the circumference among the side edge parts of a land part, (b) is a wear rate on the circumference among the side edge parts of a land part. It is sectional drawing which shows an early part. It is the same sectional drawing as FIG. 2 which showed the other sipe applicable to this invention. It is an expanded view which shows a part of tread part of the pneumatic tire of other embodiment according to this invention. It is an expanded view which shows a part of tread part of the pneumatic tire of further another embodiment according to this invention. It is an expanded view which shows a part of tread part of the conventional pneumatic tire. It is sectional drawing which follows the BB line in FIG. (A) is sectional drawing which shows typically the mode before kicking out (during ground contact) and after kicking out of the sipe provided in the side edge part of a land part in the pneumatic tire of FIG. (B) is a top view which shows typically the mode of the partial wear which generate | occur | produces in the side edge part of a land part in the pneumatic tire of FIG. It is a side view of a tire for explaining that a portion with early wear and a portion with slow wear occur on the circumference.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the pneumatic tire according to the embodiment of the present invention includes a conventional tire structure (not shown), for example, a pair of bead portions and a pair of sidewalls extending in the tire radial direction of the bead portions. Part and a tread part straddling between these sidewall parts, and it extends in a toroidal shape across the bead part, sidewall part and tread part, and its end part is embedded in each bead part. A carcass locked to the bead core, and a belt disposed outside the carcass in the tire radial direction. The tire structure is not limited to this, and a reinforcing layer such as a cap layer or a layer layer may be disposed on the outer side in the tire radial direction of the belt, and the ply constituting the carcass may be either a radial ply or a bias ply. good. In addition, the pneumatic tire has a specified mounting direction or rotation direction to the vehicle, and the mounting direction or rotation direction is usually formed by stamping or printing on the outer surface of the sidewall portion of the tire. However, the means for indicating the mounting direction and the rotation direction is not limited to this.

  As shown in FIG. 1, this pneumatic tire has at least one circumferential groove 2 extending in the tire circumferential direction in the tread portion 1, and four circumferential grooves 2 in the illustrated example. Five rib-shaped land portions 3 are defined. Here, the circumferential groove 2 is shown as extending linearly, but it may be wavy or zigzag extending along the tire circumferential direction. In the figure, the symbol I indicates the rotation direction of the tire.

  Further, the pneumatic tire is adjacent to the circumferential groove 2 and extends in the tire circumferential direction. At least one of the side end portions 3a of the land portion 3, in this case, the both side end portions 3a, one end thereof is circumferential. A plurality of sipes (also referred to as multi-sipes) 4 that open in the directional groove 2 and terminate in the land portion 3 at the other end are disposed at intervals in the tire circumferential direction. Here, “sipe” means a narrow groove having a groove width that at least partially closes when the tire contacts the ground, and the groove width can be set to 0.5 mm to 2 mm, for example. “At the time of ground contact” is an industrial standard that is valid for the area where tires are produced and used. In Japan, JAMAT (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARD MANUAL, in the United States, the tires are filled with the air pressure (maximum air pressure) corresponding to the maximum load capacity in the air pressure-load capacity correspondence table defined in YEAR BOOK of TRA (THE TIRE and RIM ASSOCATION INC.). It means a state of pressing against a flat surface with a load of 80%.

  In the illustrated example, the sipe 4 extends linearly, but may extend while being curved or bent on the development view of the tread. Further, in the illustrated example, the sipe 4 is arranged in parallel to the tire width direction, but may be arranged to be inclined at 60 ° or less with respect to the tire width direction. Further, as shown in FIG. 1, the sipes 4 are preferably arranged at regular intervals in the tire circumferential direction.

  And in this pneumatic tire, as shown in FIG. 2, the sipe 4 is a cross section along a plane parallel to the tire equator plane E, as shown in FIG. The extending direction from the outer end toward the inner end in the tire radial direction is inclined in the direction opposite to the tire rotation direction with respect to the normal m of the land surface, and the sipe 4 is inclined with respect to the normal m The angle θ is formed to increase stepwise from the outer end in the tire radial direction toward the inner end in the tire radial direction.

More specifically, the sipe 4 has two bent portions 4a and 4b between an outer end in the tire radial direction and an inner end in the tire radial direction, and the inclination angle θ is determined by the bent portions 4a and 4b. It will change over time. That is, of the two bent portions 4a and 4b, the one closer to the land surface is the first bent portion 4a, and the one far from the land surface is the second bent portion 4b. the inclination angle θ with respect to the normal of a line connecting the end and the first bent portion 4a and alpha, of the sipe 4, the inclination angle θ with respect to the normal of a line connecting the first bent portion 4a and the second bent portion 4b Is β, and the inclination angle θ of the sipe 4 with respect to the normal line of the second bending portion 4b and the inner end in the tire radial direction is γ, these inclination angles α, β and γ are α <Β <γ is satisfied. The outer end of the sipe 4 in the tire radial direction and the first bent portion 4a, the first bent portion 4a and the second bent portion 4b, and the second bent portion 4b and the inner end in the tire radial direction are all straight. It consists of parts 4c, 4d and 4e.

  In the pneumatic tire having such a configuration, a cross section parallel to the tire equatorial plane E is schematically shown, as shown in FIGS. 3 (a) and 3 (b), in which the side end portion 3a of the land portion 3 is schematically shown. Looking at the sipe 4 with respect to the outer end in the tire radial direction, the extending direction is the direction opposite to the tire rotation direction I (that is, the direction opposite to the direction in which the shearing force acts and the tire traveling direction). Therefore, the amount of fluctuation of the side end 3a of the land portion 3 adjacent to the sipe 4 during tire rolling can be reduced, and the side end 3a of the land portion 3 can be reduced. In addition, it is possible to reduce uneven wear that occurs in a portion of the tire in the traveling direction side as viewed from the sipe 4 (indicated by hatching in FIG. 3B). Moreover, as already demonstrated with reference to FIG. 11, when the part with a fast wear rate and the slow part generate | occur | produce on the periphery in the side edge part 3a of the land part 3, the sipe 4 of a part with a fast wear rate generate | occur | produced. The inclination angle θ with respect to the normal m (see FIG. 4B) is larger than the inclination angle θ with respect to the normal m of the sipe 4 where the wear rate is slow (see FIG. 4A), and the wear rate is high. Since the portion is less likely to be worn than the portion having a low wear rate, the wear rate on the circumference is made uniform.

  Therefore, the uneven wear of the side end 3a adjacent to the circumferential groove 2 of the land portion 3 partitioned by the circumferential groove 2 is sufficiently suppressed, and the unevenness on the circumference at the side end 3a is suppressed. It becomes possible to suppress uniform wear.

  Further, in the above embodiment, since each sipe 4 is provided with two bent portions 4a and 4b, and through the bent portions 4a and 4b, the inclination angle θ of the sipe 4 with respect to the normal m is changed. The effect of making the wear rate uniform on the circumference is the effect of normal tire wear from the beginning to the middle of wear (wear from about 1/3 of the length of the sipe 4 in the depth direction) and from the middle to the end of wear. (Wear up to about 2/3 of the length in the depth direction of the sipe 4) can be obtained twice, and uneven wear on the circumference can be suppressed over a longer period.

By the way, in the said embodiment, it is preferable that the said inclination | tilt angles (alpha), (beta), and (gamma) satisfy | fill 10 degrees <= (alpha) <= 30 degrees and 15 degrees <= (beta) <= 60 degrees and 30 degrees <= γ <= 75 degrees. The reason is that if the inclination angle α is less than 0 °, the portion of the side end portion 3a of the land portion 3 adjacent to the sipe 4 is easily deformed when the tire rolls, and uneven wear of the portion increases. This is because if the inclination angle exceeds 30 °, the effect of increasing the effect of suppressing uneven wear through an inflection point after the initial wear is diminished. Also, if the inclination angle β is less than 15 °, the difference in the effect of suppressing uneven wear from the initial stage of wear becomes small, and if the inclination angle β exceeds 60 °, the effect of suppressing the uneven wear from the middle period of uneven wear becomes small. Because. Furthermore, if the inclination angle γ is less than 30 °, the difference in the effect of suppressing uneven wear from the middle stage of wear becomes small, and if the inclination angle γ exceeds 75 °, it becomes difficult to satisfy L1> L2.

  Further, the distance along the tire circumferential direction between the outer ends in the tire radial direction of the sipe 4 adjacent in the tire circumferential direction (distance between the sipe 4) is L1, and the outer end of the sipe 4 in the tire radial direction and the tire diameter. When the distance along the tire circumferential direction between the inner ends of the direction is L2, it is preferable that the distances L1 and L2 satisfy L1> L2. This is because when the distances L1 and L2 are L1 ≦ L2, the distance between the sipe 4 is small, the portion between the sipe 4 is easily deformed, and the effect of suppressing uneven wear is reduced.

  Furthermore, in the above embodiment, the distance along the normal line m from the outer end of the sipe 4 in the tire radial direction to the first bent portion 4a is D1, and the sipe 4 has the first bent portion 4a to the first bent portion 4a. 2 A distance along the normal m to the bent portion 4b is D2, and a distance along the normal m from the second bent portion 4b of the sipe 4 to the inner end in the tire radial direction is D3. When the distance along the normal m from the outer end in the tire radial direction to the inner end in the tire radial direction is D4, the distances D1, D2, and D3 are (D4 × 1/4) ≦ D1 ≦ (D4 × 1/2) and (D4 × 1/4) ≦ D2 ≦ (D4 × 1/2) and (D4 × 1/4) ≦ D3 ≦ (D4 × 1/2) are preferably satisfied. When D1, D2, or D3 is less than D4 × 1/4, the effect of increasing the uneven wear suppression effect in the initial stage, middle stage, and end stage is reduced step by step, and D1, D2, or D3 is D4 * 1/2. This is because if one of D1, D2, and D3 exceeds 1, the other distance becomes smaller, and the effect of increasing the uneven wear suppression effect in the initial stage, middle stage, and end stage in stages decreases.

  Preferably, the depth D4 of each sipe 4 is in the range of 60 to 95% of the groove depth of the circumferential groove. Thereby, the partial wear suppression effect can be maintained until the end of wear.

  Preferably, the distance along the tire width direction from one end opening in the circumferential groove 22 to the other end terminating in the land portion 3 of each sipe 4 is W1, and the width of the land portion 3 (tire width direction). 1) ≦ W1 / W2 ≦ 1/4, where W2 is the distance along the line. The sipe 4 interval L1 and the distance W1 preferably satisfy 0.2 ≦ L1 / W1 ≦ 5. By setting the length W1 of the sipe 4 and the sipe 4 interval L1 in this way, uneven wear resistance can be obtained more reliably. If W1 / W2 is less than 1/30, the rigidity of the circumferential edge portion of the land portion 3 cannot be sufficiently reduced, and there is a possibility that uneven wear cannot be sufficiently suppressed. If it exceeds 4, the rigidity of the land portion 3 may be excessively lowered and the steering stability may be impaired, and in addition, a sipe 4 end tear may occur. In addition, when L1 / W1 is less than 0.2, the rigidity of the land portion 3 may be excessively reduced due to the denseness of the sipe 4, and the steering stability may be impaired, and if L1 / W1 exceeds 5, There is a possibility that the side end portion 3a of the portion 3 is too rigid and the uneven wear cannot be sufficiently suppressed.

  While the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the claims. For example, the sipe 4 may not have a bent portion, and as shown in FIG. 5, the inclination angle θ with respect to the normal m increases from the outer end in the tire radial direction toward the inner end in the tire radial direction. You may comprise so that it may increase continuously. In addition, when the inclination angle θ of the sipe 4 continuously changes, the inclination angle θ indicates an angle formed by a tangent at the intersection of the straight line parallel to the tire radial direction and the sipe 4 with the tire radial direction. According to such a configuration, the effect of suppressing uneven wear can be continuously enhanced from the initial stage of wear to the end stage. The sipe 4 may have three or more bent portions. Moreover, although the land part 3 was demonstrated as the rib-shaped land part 3 in the said embodiment, only the land part 3 arrange | positioned at both shoulder sides is made into the rib-shaped land part 3 as shown in FIG. The center-side land portion 3 sandwiched between the land-like portions 3 may be constituted by a plurality of block-like land portions 3, or a plurality of land portions 3 arranged on both shoulder sides as shown in FIG. It is good also as the rib-shaped land part 3 comprised by the block-shaped land part 3, and the land part 3 pinched | interposed into these block-shaped land parts 3 is good. Furthermore, the sipe 4 does not need to be provided in all the land portions 3, and the sipe 4 may be provided in only one land portion 3.

Next, a pneumatic tire according to the invention (tires of Examples 1 to 6 ) and a pneumatic tire as a comparison (tires of Comparative Examples 1 and 2 ) were prototyped and tested for uneven wear resistance. To do. The tires of Examples 1 to 6 and the tires of Comparative Examples 1 and 2 are pneumatic radial tires having a tire size of 295 / 75R22.5, and the test was performed on a rim having a size of 8.25 × 22.5. The inside pressure (760 kPa) based on the TRA standard was filled inside.

Here, the tires of Examples 1 to 6 and Comparative Example 2 have the tread pattern shown in FIGS. 1 and 2 in the tread portion, and detailed specifications are as shown in Table 1.

  The tire of Comparative Example 1 has the tread pattern shown in FIGS. 8 and 9 in the tread portion, and detailed specifications are as shown in Table 1.

In the performance test for uneven wear resistance performance, each test tire was run under a speed of 70 km / h (constant) on a wear drum tester set to simulate actual running conditions until the tires were actually worn. The amount of uneven wear (step amount) at the side edge of the land adjacent to the circumferential groove during 25% wear, 40% wear, 50% wear, 65% wear and 75% wear It was performed by measuring. In addition, at 25% wear, 40% wear, 50% wear, 65% wear and 75% wear, what percentage of the groove depth of the entire tread decreased with respect to the new groove main groove depth? Judge with.
The results are shown in Table 2. The uneven wear resistance performance in Table 2 is based on the result (average value) at 50% of the tire of Comparative Example 1 being 100, and the results (average value) of the tires of Examples 1 to 6 and Comparative Example 2 are indexed. The smaller the value, the better the uneven wear resistance at the side edge of the land. Further, the non-uniform wear resistance performance shown in Table 2 shows the portion with the largest uneven wear amount on the circumference (the portion with the fastest wear development) and the smallest uneven wear amount at the time of 50% wear of the tire of Comparative Example 1. The difference from the portion (the portion where wear progresses slowly) is set to 100, and the difference between the portion with the largest amount of uneven wear and the portion with the smallest amount of uneven wear on the circumference for Examples 1 to 6 and Comparative Example 2 is an index. The smaller the numerical value, the more the uneven wear that occurs on the circumference is suppressed.

From the above results, it was confirmed that the tires of Examples 1 to 6 to which the present invention was applied exhibited superior uneven wear resistance performance as compared with the tires of Comparative Examples 1 and 2 . In addition, it was confirmed that the tires of Examples 1 to 6 to which the present invention was applied were prevented from being unevenly worn on the circumference as compared with the tire of Comparative Example 1.

  Thus, according to the present invention, the uneven wear of the side end adjacent to the circumferential groove of the land portion partitioned by the circumferential groove is sufficiently suppressed, and the circumferential unevenness at the side end is not achieved. It has become possible to provide a pneumatic tire capable of suppressing excessive wear.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Circumferential groove 3 Land part 3a Side edge part of land part 4 Sipe 4a 1st bending part 4b 2nd bending part I Rotation direction of tire R Tire radial direction

Claims (4)

A tire rotation direction is designated, and a tread portion is provided with a land portion defined by at least one circumferential groove extending along the tire circumferential direction, and the land portion is adjacent to the circumferential groove. In the pneumatic tire in which a plurality of sipes whose one ends in the tire width direction are opened in the circumferential groove are provided at intervals in the tire circumferential direction at the side ends,
The sipe has a cross-section along a plane parallel to the tire equatorial plane, and the extending direction from the outer end toward the inner end in the tire radial direction is based on the outer end in the tire radial direction opening on the land surface. The inclination of the sipe with respect to the normal to the normal of the land surface is inclined in the tire radial direction from the outer end of the tire radial direction. It increases toward the end, and Ri inclination angle der 10 ° or more with respect to the normal line from the outer end of the tire radial direction, wherein the sipe has an outer end of the tire radial direction of the tire radial direction A pneumatic tire having two bent portions between the inner end and the inclined angle changes through the bent portions . Of the two bent portions, the one closer to the land surface is the first bent portion, the one far from the land surface is the second bent portion, and the outer end of the sipe in the tire radial direction and the first and the inclination angle with respect to the normal line of the line segment connecting the first bent portion and the alpha, the sipe, the angle of inclination with respect to the normal line of the line segment connecting the first bent portion and the second bend and β When the inclination angle with respect to the normal to the line segment connecting the second bent portion and the inner end in the tire radial direction of the sipe is γ, the inclination angles α, β, and γ are 10 ° ≦ The pneumatic tire according to claim 1 , wherein α ≦ 30 ° and 15 ° ≦ β ≦ 60 ° and 30 ° ≦ γ ≦ 75 ° are satisfied. The distance along the tire circumferential direction between the outer ends in the tire radial direction of the sipes adjacent to each other in the tire circumferential direction is L1, and the outer end in the tire radial direction and the inner end in the tire radial direction of the sipes are The pneumatic tire according to claim 1 or 2 , wherein each distance L1, L2 satisfies L1> L2, where L2 is a distance along the tire circumferential direction. Of the two bent portions, the one closer to the land surface is the first bent portion, the one far from the land surface is the second bent portion, and the first of the sipe from the outer end in the tire radial direction is the first bent portion. The distance along the normal line to the first bent portion is D1, and the distance of the sipe along the normal line from the first bent portion to the second bent portion is D2, and the sipe The distance along the normal from the two bent portions to the inner end in the tire radial direction is D3, and the sipe is along the normal from the outer end in the tire radial direction to the inner end in the tire radial direction. The distances D1, D2 and D3 are (D4 × 1/4) ≦ D1 ≦ (D4 × 1/2) and (D4 × 1/4) ≦ D2 ≦ (D4 × 1 / 2) and (D4 × 1/4) ≦ D3 satisfies ≦ a (D4 × 1/2), the pneumatic according to claim 1 or 2 I hate.

Images