JP5342622B2 - Pneumatic tire - Google Patents

Abstract

PURPOSE: A pneumatic tire is provided to improve driving performance on icy roads while maintaining steering stability on dry roads by controlling the angle, the number, and the end position of sipping lines in sipping groups. CONSTITUTION: A pneumatic tire comprises a landing part(5) and multiple sipping groups(13). The landing part is formed in between a ground terminal and circumferential grooves(3a,3b). The edge(9) of the landing part is formed along the circumferential grooves or the ground terminal. The sipping groups are formed along the circumference of a tire and comprise at least three sipping lines in the landing parts. The angle of the sipping groups gradually increases, going from a sipping line(12s) arranged in one side of the tire to a sipping line arranged in the other side thereof. The end position(12e) of the sipping lines is adjacent to the edge(9b) of the landing part.

Description

  The present invention relates to a pneumatic tire capable of improving running performance on an icy snow road while maintaining steering stability on a dry road.

  Conventionally, in order to improve running performance on icy and snowy roads, pneumatic tires are known in which edge components are increased by providing sipings extending parallel to each other on land portions of a tread portion. As related techniques, there are Patent Documents 1 and 2 below.

JP 2006-51891 A JP 2006-160107 A

  However, the pneumatic tire as described above has a problem that the rigidity of the land portion is likely to be lowered due to a large number of sipings, and the steering stability on the dry road surface is lowered.

  The present invention has been devised in view of the actual situation as described above, and specifies the siping arrangement angle, the number, and the terminal position of the siping group extending from the land portion edge of the land portion formed in the tread portion. The main purpose is to provide a pneumatic tire capable of improving the running performance on an icy and snowy road while maintaining the steering stability on a dry road surface.

  According to the first aspect of the present invention, the tread portion is provided with a plurality of circumferential grooves extending continuously in the tire circumferential direction, and between the ground contact end and the circumferential groove and the circumferential groove. A pneumatic tire in which a land portion is formed, wherein the land portion has a land portion edge along the circumferential groove or the ground contact end of the land portion, and at least one side of the land portion edge A plurality of siping groups comprising three or more sipings extending in the tire portion in the tire circumferential direction, extending at an angle of 10 to 80 ° with respect to the tire axial direction and inclined in the same direction, The angle gradually increases from the siping disposed on one side of the tire circumferential direction toward the siping disposed on the other side, and the end position of the siping approaches the land portion edge on the other side of the land portion. It is characterized by that.

  In the invention according to claim 2, the land portion is provided with a circumferential narrow groove extending in a zigzag manner by alternately providing an inclined portion on one side and an inclined portion on the other side with respect to the tire circumferential direction, 2. The pneumatic tire according to claim 1, wherein in the siping group, an end position of the siping is arranged corresponding to an inclination direction of the inclined portion on the one side or the other side adjacent to the end position and the tire axial direction. It is.

  According to a third aspect of the present invention, the siping group includes a first siping group extending from the land portion edge on the one side and a second siping group extending from the land portion edge on the other side. The pneumatic tire according to claim 1 or 2, wherein the two siping groups are alternately provided in the tire circumferential direction.

  The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the land portion edge has a zigzag shape.

  In the pneumatic tire of the present invention, the tread portion is provided with a plurality of circumferential grooves extending continuously in the tire circumferential direction, so that the land portion is between the ground contact end and the circumferential groove and between the circumferential grooves. Is formed. The land portion has a land portion edge along the circumferential groove or the ground contact end of the land portion, and is at an angle of 10 to 80 ° with respect to the tire axial direction from the land portion edge on at least one side and the same A plurality of siping groups consisting of three or more sipings extending in the direction and terminating in the land portion are provided in the tire circumferential direction. In the siping group, the angle gradually increases from the siping disposed on one side in the tire circumferential direction toward the siping disposed on the other side, and the end position of the siping is on the land edge on the other side. Get closer.

  Such a pneumatic tire is provided with a siping group composed of sipings extending from the land edge to the tire axial direction at an angle of 10 to 80 ° and inclined in the same direction. Such siping is useful for improving the running performance on an icy road by exhibiting a balanced edge effect in both the tire circumferential direction and the tire axial direction. Moreover, since the length of the longitudinal direction of siping can be enlarged by making the said angle 10 degrees or more, a big edge effect is exhibited. Moreover, since the inclination of siping is the same direction, it is suppressed that siping crosses mutually and it prevents that the rigidity of a crown land part falls too much.

  In addition, since the siping group is formed by three or more sipings terminating in the land portion, it suppresses an excessive rigidity decrease in the land portion, and maintains a stable driving performance on a dry road, while providing a large edge effect. Concentrate and improve friction performance on ice to further improve running performance.

  Further, the siping group is configured such that the angle gradually increases from the siping disposed on one side in the tire circumferential direction toward the siping disposed on the other side, and the end position of the siping is a land on the other side of the land portion. Close to the edge. That is, since the pneumatic tire of the present invention is provided with siping at different angles, the edge effect is exhibited according to the turning angles in multiple directions. Further, the siping having the large angle is formed to have a longer length in the longitudinal direction than the siping having the small angle. That is, siping with a large angle secures a large edge component in the tire circumferential direction, and thus can improve the straight running stability. Moreover, the rigidity of the central portion of the crown land portion can be reduced by providing the end position of the siping having a large angle on the other land portion edge side of the land portion. Thereby, the deformation in the tire axial direction of adjacent sipings becomes flexible, and the edge effect is effectively exhibited up to the end position of siping. Therefore, the pneumatic tire of the present invention further improves the running performance on icy roads.

It is an expanded view of the tread part which shows one Embodiment of this invention. It is the elements on larger scale of FIG. It is the elements on larger scale of FIG. 3 is a development view of a tread portion of Comparative Example 1. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire of this embodiment (hereinafter, simply referred to as “tire”) can be suitably used as a studless tire for a passenger car, for example, and the tread portion 2 includes a tire. A pair of crown circumferential grooves 3 disposed on both sides of the equator C and continuously extending in the tire circumferential direction; and a pair of shoulder circumferential grooves 4 extending continuously outside the crown circumferential groove 3 in the tire circumferential direction; The crown land portion 5 extending continuously in the tire circumferential direction between the crown circumferential grooves 3, 3, the middle land portion 6 between the crown circumferential groove 3 and the shoulder circumferential groove 4, and the shoulder A shoulder land portion 7 disposed between the circumferential groove 4 and the ground contact Te is divided.

  When the groove width of the crown circumferential groove 3 and the shoulder circumferential groove 4 (the groove width perpendicular to the longitudinal direction of the groove, hereinafter the same applies to other grooves) is reduced, the snow column shear force on the snow road On the contrary, when the groove width is increased, the rigidity of the land portion and the ground contact area may be reduced, and the handling stability on the dry road may be reduced. From such a viewpoint, the groove width of the crown circumferential groove 3 is about 1.0 to 7.0% of the tread grounding width TW, and the shoulder circumferential groove 4 is 2.2 of the tread grounding width TW. About 5 to 7.0% is preferable. From the same viewpoint, the groove depth (not shown) of the crown circumferential groove 3 and the shoulder circumferential groove 4 is preferably 7.0 to 12.5 mm.

  Further, since the crown land portion 5 extends on the tire equator C, a large ground pressure acts. For this reason, when the width of the crown land portion 5 in the tire axial direction is reduced, the rigidity is lowered and the steering stability on the dry road surface tends to be lowered. On the contrary, when the width is increased, the snow discharge performance is lowered. There is a fear. Accordingly, the width (maximum width) of the crown land portion 5 in the tire axial direction is preferably about 15.0 to 22.0% of the tread ground contact width TW.

  Similarly, in order to balance the rigidity of the land portion and the snow discharge performance, the width (maximum width) of the middle land portion 6 in the tire axial direction is 18.0 to 28.0% of the tread ground contact width TW, The width (maximum width) of the shoulder land portion 7 in the tire axial direction is preferably 10.0 to 18.0% of the tread ground contact width TW.

  Here, the “tread contact width” TW is a contact end Te when a normal load is loaded on a normal rim that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to a flat surface. The distance in the tire axial direction between Te. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA and “Design Rim” for TRA. For ETRTO, use "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA and table for TRA. The maximum value described in TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES is "INFLATION PRESSURE" for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, the “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum load capacity” for JATMA and “TIRE” for TRA. The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” in the case of ETRTO.

  The crown land portion 5 has a land portion edge 9 along the crown circumferential groove 3. The middle land portion 6 has a middle land portion edge 10a along the crown circumferential groove 3 on the inner side in the tire axial direction and a middle land portion edge 10b along the shoulder circumferential groove 4 on the outer side in the tire axial direction. The shoulder land portion 7 has a shoulder land portion edge 11a along the shoulder circumferential groove 4 on the inner side in the tire axial direction and a shoulder land portion edge 11b along the ground contact end Te on the outer side in the tire axial direction.

  As shown well in FIG. 2, the crown land portion 5 has a siping extending from one land portion edge 9a (right side in the figure) to the tire axial direction at an angle θ1 of 10 to 80 ° and inclined in the same direction. A siping group 13 consisting of 12 is provided. Such a siping 12 is useful for improving the running performance on an icy road by exhibiting an edge effect with good balance in both the tire circumferential direction and the tire axial direction. Further, siping having an angle of 10 ° or more exhibits a large edge effect because the length in the longitudinal direction is increased. When the angle θ1 is less than 10 ° or exceeds 80 °, the edge component in the tire circumferential direction or the edge component in the tire axial direction becomes small, and the edge effect cannot be exhibited in a well-balanced manner. For this reason, the angle θ1 is preferably 45 ° or more, and preferably 70 ° or less. Moreover, since the inclination of the siping 12 is made the same direction, it is suppressed that the siping 12 cross | intersects each other and it prevents that the rigidity of the crown land part 5 falls excessively.

  The siping group 13 includes three or more semi-open type sipings 12 that terminate in the crown land portion 5. Such a siping group 13 composed of three or more sipings 12 exerts a large edge effect in a concentrated manner, and increases the frictional force on ice to further improve the running performance. From this point of view, the siping group 13 is preferably composed of four or more sipings 12 and is desirably composed of six or less sipings 12. Moreover, the siping 12 can suppress the excessive rigidity fall of the crown land part 5 by setting it as a semi-open type.

  Further, the siping group 13 (right side in the figure) of the present embodiment is arranged from the siping 12s arranged on one side (lower side in the figure) to the other side (upper side in the figure). The angle θ1 gradually increases toward 12t, and the terminal position 12e of the siping 12 approaches the other land portion edge 9b (left side in the figure) of the crown land portion 5. As described above, the crown land portion 5 is provided with the sipings of different angles closely, so that the edge effect is exhibited according to the multidirectional turning angle. Further, the siping 12t having a large angle θ1 is formed with the length La larger than that of the siping 12s having a small angle θ1. Therefore, a large edge component in the tire circumferential direction is ensured by siping with a large angle, and the straight running stability is particularly improved. Further, since the end position 12e of the siping having a large angle θ1 is provided on the other land portion edge 9b side of the crown land portion 5, the rigidity of the central portion of the crown land portion 5 can be reduced. Thereby, the deformation of the adjacent siping in the tire axial direction becomes flexible, and the edge effect is effectively exhibited up to the end position 12e of the siping 12. Therefore, the pneumatic tire of the present invention further improves the running performance on icy roads.

  Further, the siping group 13 of the present embodiment is formed so that the tire circumferential direction in which the siping 12 extends toward the end position 12e and the tire circumferential direction in which the angle θ1 of the siping 12 gradually increases are different. That is, in FIG. 2, the siping group 13a extending from the land portion edge 9a on one side extends from top to bottom toward the end position 12e, while the angle θ1 of the siping 12 gradually increases from bottom to top. Yes. In such a siping group 13, the tire circumferential direction distance Lb between the sipings 12 adjacent to each other in the tire circumferential direction decreases toward the inner side of the crown land portion 5. However, the rigidity of the entire land is made uniform. Thereby, the fall of the crown land portion 5 is suppressed, and the running performance on the icy road is further improved. Note that the siping group 13 is not limited to such an embodiment. For example, the tire circumferential direction in which the siping 12 extends and the tire circumferential direction in which the angle θ1 gradually increases are formed in the same direction. May be. Such a siping group 13 can also exhibit an edge effect according to the above-described multidirectional turning angles.

  Further, the tire circumferential direction distance Lb increases toward the land portion edge 9 side of the crown land portion 5. Thereby, the rigidity fall of the land part edge 9 with a low rigidity inherently is suppressed.

  In addition, the siping 12 which comprises the siping group 13 of this embodiment shall be formed in the tire circumferential direction length of each end position 12e, 12e of the siping 12 adjacent to the tire circumferential direction within 2 mm.

  In this embodiment, the siping group 13 includes a first siping group 13a extending from the one land portion edge 9a, and a second siping group 13b extending from the other land portion edge 9b (left side in the figure). It is comprised including. The first and second siping groups 13a and 13b are alternately provided in the tire circumferential direction. Thereby, the edge effect is exhibited in a balanced manner at both side edges 9a, 9b of the crown land portion 5.

  Furthermore, in this embodiment, the siping 12 of the first siping group 13a and the siping 12 of the second siping group 13b are inclined in opposite directions. That is, the siping 12 of the first siping group 13a is tilted upward to the right, while the siping 12 included in the second siping group 13b is tilted downward to the right. As a result, the edge effect is exhibited in a well-balanced manner during straight travel and turning.

  Moreover, since the siping 12 of this embodiment is formed linearly, the rigidity of the crown land portion 5 is not excessively lowered. The sipe width of such a sipe 12 is desirably about 0.2 to 1.0 mm in order to ensure a good balance between running performance on an icy road and steering stability on a dry road. Note that the siping 12 is not limited to such an embodiment, and may be a zigzag shape or a wave shape as long as the above-described effect is exhibited.

  Further, the crown land portion 5 has alternately inclined portions 14a on one side (in the present embodiment, right-handed inclination) and inclined portions 14b on the other side (in the present embodiment, rising to the left) in the tire circumferential direction. By being provided, the circumferential narrow groove 14 extending in a zigzag shape is provided. Such a circumferential narrow groove 14 exhibits the edge effect of the groove edge of the circumferential narrow groove 14 and helps to improve the running performance on an icy road.

  In the siping group 13, the end position 12e of the siping 12 is inclined in the inclined portion 14a on one side or the inclined portion 14b on the other side of the circumferential narrow groove 14 adjacent to the end position 12e in the tire axial direction. Are arranged corresponding to In the present embodiment, the end position 12e1 of the first siping group 13a is arranged corresponding to the inclination direction of the other inclined portion 14b adjacent in the tire axial direction, and the end position 12e2 of the second siping group 13b. Are arranged corresponding to the inclination direction of the inclined portion 14a on one side adjacent to the tire axial direction. Such a siping group 13 ensures the length La and exerts a large edge effect. The “corresponding to the direction of inclination of the inclined portion” means that the shortest distance Lc between each terminal position 12e and the circumferential narrow groove 14 is constant, as well as the shortest distance Lc in the siping group 13. It is assumed that the ratio Lcm / Lcn between the maximum value Lcm and the minimum value Lcn (both not shown) is 2.0 or less.

  Further, the shortest distance Lc secures the flexibility of the central portion of the crown land portion 5 and secures the edge effect in the vicinity of the terminal position 12e of the siping 12, while suppressing an excessive decrease in rigidity on the dry road. In order to maintain the steering stability, it is preferably 0.5 mm or more, more preferably 1.0 mm or more, and preferably 4.0 mm or less, more preferably 3.0 mm or less.

  When the circumferential narrow groove 14 is formed in a straight line, the edge effect is strongly exerted only with respect to the arrangement angle of the circumferential narrow groove 14, and the edge effect with respect to other directions is relatively Undesirably small. From such a viewpoint, the inclined portion 14a on one side of the present embodiment is formed in an arc shape that is smoothly convex toward the land portion edge 9b on the other side, and the inclined portion 14b on the other side is formed on the one side. It is formed in an arc shape that is smoothly convex toward the land portion edge 9a on the side.

  In such a circumferential narrow groove 14, the ratio Ld between the chord length Ld of the inclined portions 14a and 14b on one side and the other side and the shortest distance Le from the chord to the apex X of the inclined portions 14a and 14b. / Le is preferably in the range of 5.0 to 8.0. Thereby, while exhibiting the edge effect of the groove edge of the circumferential narrow groove 14 in multiple directions, the decrease in rigidity of the crown land portion 5 is suppressed, and the running performance on the icy road and the steering stability on the dry road are improved. Improve in a balanced manner.

  Further, in the circumferential narrow groove 14 of the present embodiment, the inner end 14ae of the inclined portion 14a on one side is terminated on the inclined portion 14b on the other side, and the inner end 14be of the inclined portion on the other side is It terminates on the side inclined portion 14a. Such a circumferential narrow groove edge 14 is useful for reducing the rigidity of the central portion of the crown land portion 5 and making the rigidity of the entire land portion uniform while maintaining high rigidity in the vicinity of the land portion edge 9. Thereby, the circumferential direction narrow groove 14 of this embodiment prevents the crown land part 5 from falling, and improves the running performance on an icy road.

  In addition, by such a circumferential narrow groove 14, the crown land portion 5 of the present embodiment has one crown circumferential groove 3 a (right side in the figure), one inclined portion 14 a adjacent to the tire circumferential direction, 14a and the crown land piece 5a on the one side (right side in the figure) surrounded by the inclined part 14b on the other side, the crown circumferential groove 3b on the other side (left side in the figure), and the other adjacent in the tire circumferential direction The side inclined portions 14b and 14b and the other side crown land portion 5b (left side in the figure) surrounded by the one side inclined portion 14a are alternately arranged in the tire circumferential direction.

  In the crown land portion pieces 5a and 5b, the virtual siping 12Y (indicated by a broken line) intersects the circumferential narrow groove 14 by extending the siping 12t having the largest angle θ1 in the siping group 13 in the length direction thereof. ) And the inclined surface portions 14a and 14b adjacent to the virtual siping 12Y, the surface area Sa of the crown land pieces 5a and 5b on which the virtual siping 12Y is formed (assuming that the entire siping 12 is filled) The surface area is preferably 23% or more, more preferably 25% or more, and preferably 37% or less, more preferably 35% or less. When the surface area Sa is increased, the sipings 12 are excessively dense, the rigidity of the portion is deteriorated, and the steering stability on the dry road may be deteriorated. On the other hand, when the surface area Sa is reduced, the rigidity of this portion is lowered and the block is likely to fall down, and the running performance on an icy road may be deteriorated.

  The groove width of the circumferential narrow groove 14 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and preferably 1.5 mm or less, in order to effectively exhibit the above-described action. More preferably, it is 1.0 mm or less.

  Moreover, the land portion edge 9 of the crown land portion of the present embodiment has a zigzag shape. As shown in FIG. 3, the land edge 9 is mainly composed of an arcuate curve that protrudes toward the tire equator C side and extends at an angle α1 in the range of 0 to 30 °, for example, with respect to the tire circumferential direction. The circumferential pieces 15 and the axial pieces 16 constituted by straight lines extending at an angle α2 in the range of, for example, 0 to 10 ° with respect to the tire axial direction are alternately arranged. The land edge 9 has an intersection 17 where the circumferential piece 15 and the axial piece 16 intersect. The intersection 17 includes a first intersection 17 s that forms a corner-shaped corner portion with the circumferential piece 15 and the axial piece 16, and a projection with a corner that protrudes with the circumferential piece 15 and the axial piece 16. And a second intersection point 17t constituting the part. Thereby, the land portion edge 9 exhibits an edge effect both in the tire axial direction and in the tire circumferential direction. In the case where the circumferential piece 15 and / or the axial piece 16 are curved, the tangent lines may be in the range of the angles α1 and α2.

  Further, in the circumferential piece 15 of the present embodiment, the first circumferential piece 15a and the second circumferential piece 15b having a tire circumferential length longer than the first circumferential piece 15a are alternately arranged. Is provided. Thereby, the land portion edge 9 of the present embodiment is smaller than the small pitch P1 in which the tire circumferential pitch between the first intersections 17a and 17b adjacent in the tire circumferential direction is small, and larger than the small pitch P1. Large pitches P2 are alternately formed. Such a land portion edge 9 can enhance the edge effect while suppressing a decrease in rigidity of the land portion edge 9.

  Further, in order to ensure the rigidity balance between the one land portion edge 9a and the other land portion edge 9b, the small pitch P1a formed on the one land portion edge 9a is opposed to the tire axial direction. It is desirable that a small pitch on the other side is not formed on the land portion edge 9b on the other side (indicated by a broken line).

  Further, one end 12a of each siping 12 (opening portion between the siping 12 and the crown circumferential groove 3) excludes the intersection 17 in the land portion edge 9 in order not to excessively reduce the rigidity of the crown land portion 5. It is desirable to open at a position.

  Further, the siping 12 of the present embodiment is provided with a cross siping 21 that intersects substantially vertically. Thereby, the water supply / drainage performance of the siping 12 and the rigidity of each land part can be adjusted. In the present embodiment, a total of two cross sipings 18 are provided, one at each end of each siping 12.

  Further, in the present embodiment, as shown in FIG. 1, the middle land portion 6 has a middle slope that connects the crown circumferential groove 3 and the shoulder circumferential groove 4 while being inclined with respect to the tire axial direction. The middle block 8R is provided in the tire circumferential direction by separating the grooves 19 in the tire circumferential direction at an angle of 10 to 50 ° with respect to the tire axial direction.

  In the middle block 8R, the inner block edge 8i on the inner side in the tire axial direction has a circular arc shape that is convex and smooth on the inner side in the tire axial direction, and the outer block edge 8e on the outer side in the tire axial direction has a zigzag shape. Such a middle block 8R helps to ensure drainage and snow drainage by the inner block edge 8i, and the edge effect is exerted by the outer block edge 8e to improve running performance on ice roads. To help.

  Further, the middle inclined groove 20 has a smaller angle with respect to the tire axial direction toward the outer side in the tire axial direction. For this reason, the groove edge of the middle inclined groove 19 exhibits an edge effect in multiple directions, and the lateral force caused by turning of the vehicle is used to effectively remove water and snow in the crown circumferential groove 3 in the tire axial direction. Can lead to the outside. Therefore, drainage and running performance on icy and snowy roads can be improved.

  Further, as shown in FIG. 1, in the present embodiment, the shoulder land portion 7 is provided with shoulder lateral grooves 20 extending at an angle of 0 to 5 ° in the tire axial direction so as to be spaced apart in the tire circumferential direction. A substantially pentagonal shoulder block 7R is provided in the tire circumferential direction.

  Further, the middle block 6R and the shoulder block 7R are provided with sipings 21a to 21c that are opened by the crown circumferential groove 3 or the shoulder circumferential groove 4, so that the drainage property and snow in the middle land portion 6 and the shoulder land portion 7 are provided. Improve driving performance on roads and ice. Note that the sipings 21a to 21c of the present embodiment have different inclination directions and exhibit multi-directional edge effects.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, it cannot be overemphasized that this invention can be changed into various aspects, without being limited to said specific embodiment.

  A pneumatic tire of size 225/65 / R17 having the basic structure of FIG. 1 was prototyped based on the specifications in Table 1, and the braking performance on ice and the steering stability performance on a dry road surface of each sample tire were tested. The test method is as follows.

<Ice braking performance>
Each test tire is mounted on all wheels of a 2000cc vehicle under a 17 × 7.0J rim and an internal pressure of 200kPa, and full braking is applied during straight running at 40km / h on an icy road test course. The distance until the vehicle stopped was measured. The result is an index in which the reciprocal of the value of the stopping distance of the tire of Comparative Example 1 (prior art) is 100, and a larger value is better.

<Steering stability>
Under the same conditions as described above, on the dry asphalt road surface test course, steering response characteristics, rigidity, handling stability characteristics such as grips, and riding comfort were evaluated by the driver's sensuality. A comparative example 1 is displayed with a score of 100, and a larger numerical value is better.

  As a result of the test, it can be confirmed that the on-ice stability performance and the steering stability performance of the tire of the example are significantly improved as compared with Comparative Example 1.

2 tread portion 3 crown circumferential groove 9 land portion edge 9a land portion edge 9b on one side land portion edge C on the other side C tire equator 12 siping 12s siping 12t disposed on one side siping 12e disposed on the other side End position 13 Siping group Te Grounding end

Claims (4)

A pneumatic tire in which a land portion is formed between a ground contact end and the circumferential groove and by providing a plurality of circumferential grooves extending continuously in the tire circumferential direction in the tread portion. There,
The land portion has a land portion edge along the circumferential groove or a ground contact edge of the land portion, and at least an angle of 10 to 80 degrees with respect to the tire axial direction from the land portion edge on the one side and the same A plurality of siping groups consisting of three or more sipings terminating in the land and extending in the direction of the direction are provided in the tire circumferential direction,
In the siping group, the angle gradually increases from the siping disposed on one side of the tire circumferential direction toward the siping disposed on the other side, and the end position of the siping is a land on the other side of the land portion. Pneumatic tire characterized by approaching the edge The land portion is provided with a circumferential narrow groove extending in a zigzag manner by alternately providing an inclined portion on one side with respect to the tire circumferential direction and an inclined portion on the other side,
2. The pneumatic tire according to claim 1, wherein in the siping group, an end position of the siping is arranged corresponding to an inclination direction of the inclined portion on the one side or the other side adjacent to the end position and the tire axial direction. . The siping group includes a first siping group extending from the land portion edge on the one side, and a second siping group extending from the land portion edge on the other side,
The pneumatic tire according to claim 1 or 2, wherein the first and second siping groups are alternately provided in a tire circumferential direction.   The pneumatic tire according to claim 1, wherein the land edge has a zigzag shape.

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