JP2019156025A - tire - Google Patents

Abstract

To provide a tire capable of exerting excellent ice/snow road performance and superior steering stability on a dry road surface.SOLUTION: A tire comprises a tread part 2. Plural inclined grooves 10, plural central lateral grooves 12, and plural inclined land parts 13 are provided on the tread part 2. The inclined groove extends obliquely from a first tread end Te1 on one side in a tire axial direction toward a tire equator side and ends between the tire equator and the first tread end Te1, and the central lateral groove crosses the tire equator C to communicate with the inclined groove 10. The inclined land part is partitioned between inclined grooves adjacent in a tire circumferential direction. A splice groove 15 communicating the inclined grooves 10 is provided on the inclined land part 13, and the central lateral groove 12 has a groove width wider than the width of the splice groove 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a winter tire, and more particularly, to a tire suitable for running on icy and snowy roads.

  For example, Patent Document 1 below proposes a winter tire in which a plurality of inclined lateral grooves, inner joint grooves, and center joint grooves are provided in the tread portion. The inclined lateral groove extends in an inclined manner from the outside of the ground contact end to the inner end near the tire equator. The inner joint groove joins the inclined lateral grooves adjacent in the tire circumferential direction on the tire equator side. The center joint groove is disposed on the inner side in the tire axial direction from the inner joint groove and crosses the tire equator.

JP, 2006-196288, A

  In recent years, steering stability on dry road surfaces is required even for winter tires. As a result of various experiments, the inventors have found that by improving the relationship between the groove width of the inner joint groove and the center joint groove, the performance on ice and snow roads and the driving stability on the dry road surface can be improved.

  The present invention has been devised in view of the above circumstances, and its main object is to provide a tire capable of exhibiting excellent icy and snowy road performance and driving stability on a dry road surface.

  The present invention is a tire having a tread portion, and the tread portion extends obliquely from the first tread end on one side in the tire axial direction toward the tire equator side, and includes a tire equator and the first tread end. A plurality of inclined grooves divided between the plurality of inclined grooves, the plurality of central lateral grooves that communicate with the plurality of inclined grooves across the tire equator, and the inclined grooves adjacent to each other in the tire circumferential direction. In the inclined land portion, a joint groove communicating between the inclined grooves is provided, and the central lateral groove has a larger groove width than the joint groove.

  In the tire of the present invention, the inclined land portion is provided with a plurality of joint grooves, the plurality of joint grooves include an inner joint groove provided on the most tire equator side, and the central lateral groove has a length thereof. It is desirable that the groove width is larger than the maximum groove width of the inner joint groove over the entire length.

  In the tire of the present invention, it is desirable that the central lateral groove and the inner joint groove communicate with the same position of the inclined groove.

  In the tire of the present invention, it is preferable that an angle of the inner joint groove with respect to the tire axial direction is smaller than an angle of the central lateral groove with respect to the tire axial direction.

  In the tire of the present invention, it is preferable that a difference between an angle of the central lateral groove with respect to the tire axial direction and an angle of the inner joint groove with respect to the tire axial direction is 20 ° or less.

  In the tire of the present invention, each of the plurality of central lateral grooves is preferably inclined at an angle of 5 to 25 ° with respect to the tire axial direction.

  In the tire of the present invention, it is desirable that the inclined groove has an inner end portion on the tire equator side that is interrupted without being connected to another groove.

  In the tread portion of the tire of the present invention, a plurality of inclined grooves extending obliquely from the first tread end on one side in the tire axial direction toward the tire equator side and interrupted between the tire equator and the first tread end, A plurality of central lateral grooves that respectively communicate with the plurality of inclined grooves across the tire equator and a plurality of inclined land portions divided between the inclined grooves adjacent in the tire circumferential direction are provided. The inclined land portion is provided with a joint groove that communicates between the inclined grooves. The central lateral groove has a larger groove width than the joint groove.

  Such a central transverse groove forms a large and hard snow column near the tire equator where the contact pressure is high when traveling on an icy snow road, and can provide a large snow column shear force. On the other hand, the inclined land portion is provided with a joint groove having a relatively small groove width. Therefore, the inclined land portion prevents a decrease in rigidity near the joint groove and is excessively deformed when turning on a dry road surface. As a result, the handling stability on the dry road surface can be improved.

It is an expanded view of the tread part of the tire of one embodiment of the present invention. It is an enlarged view of the 1st tread part of FIG. It is an enlarged view of the outline of a 1st intermediate joint groove. It is the sectional view on the AA line of FIG. It is an enlarged view of the outline of a sloping groove, a center horizontal groove, and a joint groove. It is an enlarged view of an inclined land part. It is the BB sectional view taken on the line of FIG. It is an expanded view of the tread part of the tire of other embodiments of the present invention. It is an expanded view of the tread part of the tire of other embodiments of the present invention. It is an expanded view of the tread part of the tire of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of the tread portion 2 of the tire 1 of the present embodiment. As FIG. 1 shows, the tire 1 of this embodiment is used suitably as a winter pneumatic tire for passenger cars, for example. In another aspect of the present invention, the tire 1 can be used as, for example, a heavy-duty pneumatic tire or a non-pneumatic tire that is not filled with pressurized air inside the tire.

  The tire 1 of the present embodiment includes, for example, a directional pattern in which the rotation direction R is designated. The rotation direction R is displayed by a character or a symbol on, for example, a sidewall portion (not shown).

  The tire 1 of the present embodiment has a tread portion 2 between a first tread end Te1 and a second tread end Te2. The tread portion 2 includes a first tread portion 2A between the tire equator C and the first tread end Te1, and a second tread portion 2B between the tire equator C and the second tread end Te2. The first tread portion 2A and the second tread portion 2B are configured substantially line-symmetrically except that they are displaced in the tire circumferential direction. Therefore, each configuration of the first tread portion 2A can be applied to the second tread portion 2B.

  In the case of a pneumatic tire, the first tread end Te1 and the second tread end Te2 are the ground contact positions on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in a normal state and grounded on a plane with a camber angle of 0 °. is there. The normal state is a state in which the tire is assembled on the normal rim and is filled with the normal internal pressure, and further, there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

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

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

  “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. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The tread portion 2 is provided with a plurality of inclined grooves 10. The inclined groove 10 includes, for example, a first inclined groove 10A provided in the first tread portion 2A and a second inclined groove 10B provided in the second tread portion 2B. The first inclined groove 10A extends obliquely from the first tread end Te1 toward the tire equator C side. The second inclined groove 10B extends obliquely from the second tread end Te2 toward the tire equator C side. The second inclined groove 10B has substantially the same configuration as the first inclined groove 10A. For this reason, unless otherwise specified, the configuration of the first inclined groove 10A can be applied to the second inclined groove 10B. Each of the inclined grooves 10 forms a long snow column extending obliquely with respect to the tire axial direction when traveling on snow and shears it to obtain a large snow traction.

  In a desirable mode, each inclined slot 10A and 10B inclines in the first arrival side of rotation direction R toward tread edge Te1 and Te2 toward tire equator C side. However, the present invention is not limited to such an embodiment.

  FIG. 2 shows an enlarged view of the first tread portion 2A. As shown in FIG. 2, the inclined groove 10 is preferably curved so that, for example, an angle θ <b> 1 with respect to the tire axial direction gradually increases toward the tire equator C side. The angle θ1 is preferably, for example, 0 to 80 °. Such an inclined groove 10 can exert a snow column shear force also in the tire axial direction when traveling on snow.

  The inclined groove 10 is interrupted without crossing the tire equator C. For this reason, the first inclined groove 10A is interrupted between the tire equator C and the first tread end Te1. The second inclined groove 10B is interrupted between the tire equator C and the second tread end Te2. In a more desirable mode, the inclined groove 10 has an inner end portion on the tire equator C side that is interrupted without being connected to other grooves. Such an inclined groove 10 is useful for maintaining the rigidity in the vicinity of the tire equator C and improving the steering stability on the dry road surface.

  The distance L1 in the tire axial direction from the inner end of the inclined groove 10 (meaning the inner end in the tire axial direction of the groove center line, hereinafter the same) to the tire equator is, for example, 2.0 of the tread width TW. % To 7.0% is desirable. The tread width TW is a distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

  The inclined groove 10 desirably has a groove width that gradually increases from the tire equator C side toward the tire axial direction outer side, for example. The maximum groove width W1 of the inclined groove 10 is preferably, for example, 3.0% to 5.0% of the tread width TW. In the case of a winter tire for passenger cars, the depth of the inclined groove 10 is, for example, 6.0 to 12.0 mm, and preferably 8.0 to 9.0 mm.

  The tread portion 2 of the present embodiment is provided with a plurality of central lateral grooves 12. The central lateral groove 12 communicates with the inclined groove 10 across the tire equator C. More specifically, the central lateral groove 12 includes a first central lateral groove 12A and a second central lateral groove 12B.

  The first central lateral groove 12A is inclined in the same direction as the first inclined groove 10A. The first central lateral groove 12A branches from the first inclined groove 10A and extends in the tire axial direction, and is continuous with the second inclined groove 10B.

  The second central lateral groove 12B is inclined in the same direction as the second inclined groove 10B (shown in FIG. 1). The second central lateral groove 12B branches from the second inclined groove 10B and extends in the tire axial direction, and is continuous with the first inclined groove 10A. The first central lateral grooves 12A and the second central lateral grooves 12B are alternately provided in the tire circumferential direction. With such an arrangement of the central lateral groove 12, a multidirectional snow column shearing force can be obtained, and an excellent icy and snowy road performance is exhibited.

  The tread portion 2 is provided with an inclined land portion 13. The inclined land portion 13 is divided between adjacent inclined grooves 10 in the tire circumferential direction. The inclined land portion 13 of the present embodiment includes, for example, a region divided between the first central lateral groove 12A and the second central lateral groove 12B.

  As shown in FIG. 1, the inclined land portion 13 is divided, for example, between the first inclined land portion 13A divided between the plurality of first inclined grooves 10A and the plurality of second inclined grooves 10B. Second inclined land portion 13B. The second inclined land portion 13B has substantially the same configuration as the first inclined land portion 13A. For this reason, unless otherwise specified, the configuration of the first inclined land portion 13A can be applied to the second inclined land portion 13B.

  As shown in FIG. 2, the inclined land portion 13 is provided with a plurality of joint grooves 15 that communicate between the adjacent inclined grooves 10 in the tire circumferential direction. The joint groove 15 includes an inner joint groove 16 provided on the most tire equator C side, an intermediate joint groove 17 disposed on the first tread end Te1 side with respect to the inner joint groove 16, and a first tread end Te1 side most. And an outer joint groove 18 arranged.

  The central lateral groove 12 has a larger groove width than the joint groove 15. Such a central lateral groove 12 forms a large and hard snow column near the tire equator C where the contact pressure is high when traveling on an icy and snowy road, and can provide a large snow column shear force. On the other hand, since the slope land portion 13 is provided with the joint groove 15 having a relatively small groove width, the slope land portion prevents a decrease in rigidity in the vicinity of the joint groove 15 and is excessive when turning on a dry road surface. Therefore, it is possible to improve the steering stability on the dry road surface.

  The central lateral groove 12 of the present embodiment has, for example, a constant groove width over the entire length. Further, it is desirable that the central lateral groove 12 has a groove width W3 that is larger than the maximum groove width W4 of the inner joint groove 16 over the entire length thereof. In a more desirable aspect, the central lateral groove 12 has a larger groove width than any of the plurality of joint grooves 15. Thereby, the effect mentioned above is exhibited reliably.

  The groove width W3 of the central lateral groove 12 is, for example, preferably 1.30 times or more, more preferably 1.40 times or more, and preferably 1.70 times or less of the maximum groove width W4 of the inner joint groove 16. Preferably it is 1.60 times or less. Such a central lateral groove 12 is useful for improving the snow / snow road performance and the steering stability on the dry road surface in a well-balanced manner.

  The groove width W3 of the central lateral groove 12 of this embodiment is larger than the groove width of the inner end portion of the inclined groove 10, for example. Further, the groove width W3 of the central lateral groove 12 is smaller than the maximum groove width W1 of the inclined groove 10, for example. Such a central lateral groove 12 can improve the snow and snow road performance while suppressing uneven wear near the tire equator C.

  In the present embodiment, each of the first central lateral groove 12A and the second central lateral groove 12B has the above-described groove width. In a more desirable mode, the first central lateral groove 12A and the second central lateral groove 12B have the same groove width. Such an arrangement of the central lateral groove 12 is useful for further suppressing uneven wear near the tire equator C.

  Each central lateral groove 12 extends linearly, for example. However, the central lateral groove 12 is not limited to such an embodiment. For example, each of the plurality of central lateral grooves 12 is preferably inclined at an angle θ2 of 5 to 25 ° with respect to the tire axial direction. Such a central lateral groove 12 can be expected to have a large snow traction.

  For example, the inner joint groove 16 is located on the tire equator C side with respect to the center position (not shown) of the first tread portion 2A in the tire axial direction. The inner joint groove 16 of the present embodiment is, for example, a distance L2 from the outer end in the tire axial direction (meaning the end of the groove center line on the outer side in the tire axial direction, hereinafter the same) to the tire equator C. The width is desirably 0.10 to 0.14 times the width TW.

  In a more desirable mode, the central lateral groove 12 and the inner joint groove 16 communicate with the same position of the inclined groove 10. Accordingly, it is desirable that the central lateral groove 12 and the inner joint groove 16 extend so as to be smoothly continuous via the inclined groove 10. Note that “smoothly continuous” includes at least an aspect in which when one groove portion is virtually extended, the groove portion intersects with an end portion of the other groove portion. Such an inner joint groove 16 can form a long snow column in the tire axial direction together with the central lateral groove 12 when traveling on an icy and snowy road, and can enhance on-snow traction.

  The inner joint groove 16 extends linearly, for example. For example, the inner joint groove 16 is disposed at an angle θ3 of 80 to 90 ° with respect to the tire circumferential direction. Such an inner seam 16 helps to increase snow traction. When the inner joint groove 16 is inclined with respect to the tire axial direction, it is desirable that the inner joint groove 16 is inclined in the direction opposite to the inclined groove 10.

  The angle θ11 (not shown) of the inner joint groove 16 with respect to the tire axial direction is preferably smaller than the angle θ2 of the central lateral groove 12 with respect to the tire axial direction, for example. The difference between the angle θ2 of the central lateral groove 12 with respect to the tire axial direction and the angle θ11 of the inner joint groove 16 with respect to the tire axial direction is preferably 20 ° or less, for example. Such an inner joint groove 16 can enhance the traction on snow together with the central lateral groove 12.

  For example, one or a plurality of intermediate joint grooves 17 are arranged. In the present embodiment, two intermediate joint grooves 17 are provided between the inner joint groove 16 and the outer joint groove 18. The intermediate joint groove 17 includes a first intermediate joint groove 17A on the tire equator C side and a second intermediate joint groove 17B on the first tread end Te1 side. For example, each intermediate joint groove 17 is preferably inclined in a direction opposite to the communicating inclined groove 10.

  For example, each of the first intermediate joint groove 17A and the second intermediate joint groove 17B is preferably located closer to the tire equator C side than the center position in the tire axial direction of the first tread portion 2A. In the present embodiment, for example, in the first intermediate joint groove 17A, it is desirable that the distance L3 from the outer end in the tire axial direction to the tire equator C is 0.14 to 0.18 times the tread width TW. In the second intermediate joint groove 17B, for example, the distance L4 from the outer end in the tire axial direction to the first tread end Te1 is desirably 0.20 to 0.30 times the tread width TW. A relatively large contact pressure acts on the first intermediate joint groove 17A and the second intermediate joint groove 17B of the present embodiment when traveling on an icy and snowy road, and a hard snow column can be formed.

  The intermediate joint groove 17 is formed with a smaller angle θ4 with respect to the tire circumferential direction than the inner joint groove 16. When the intermediate joint groove 17 is bent, the angle θ4 is an angle with respect to the tire circumferential direction of an imaginary straight line connecting both ends of the groove center line. The angle θ4 of the intermediate joint groove 17 is desirably 30 to 50 °, for example.

  Each end portion of the intermediate joint groove 17 of the present embodiment is desirably displaced from the end portion of the intermediate joint groove 17 provided in the inclined land portion 13 adjacent in the tire circumferential direction. In other words, it is desirable that a plurality of three-way paths are formed by the intermediate joint groove 17 and the inclined groove 10. Such an intermediate joint groove 17 is useful for suppressing a decrease in rigidity of the tread portion 2 and improving steering stability on a dry road surface.

  FIG. 3 is an enlarged view of the outline of the first intermediate joint groove 17A as a diagram for explaining the intermediate joint groove 17. FIG. As shown in FIG. 3, the intermediate joint groove 17 of the present embodiment desirably has at least one bent portion 20, for example. In a more desirable mode, the intermediate joint groove 17 of the present embodiment includes, for example, two bent portions 20 that are convex in opposite directions. Such an intermediate splicing groove 17 is useful for forming a hard snow column, and as a result, the snow and snow road performance is improved.

  The intermediate joint groove 17 has, for example, a pair of main inclined portions 21 and a sub inclined portion 22 therebetween. The main inclined portion 21 extends, for example, from the inclined groove 10 at an angle θ5 of 45 to 55 ° with respect to the tire circumferential direction.

  The sub inclined part 22 has a length smaller than the main inclined part 21, for example. For example, the sub-inclined portion 22 is inclined in the opposite direction to the main inclined portion 21. The angle θ6 of the auxiliary inclined portion 22 with respect to the tire circumferential direction is preferably larger than the angle θ5 of the main inclined portion 21, for example. Specifically, the angle θ6 of the sub-inclined portion 22 is desirably, for example, 65 to 80 °.

  As shown in FIG. 2, for example, the outer joint groove 18 is located closer to the first tread end Te1 side than the center position of the first tread portion 2A in the tire axial direction. In the outer joint groove 18, for example, the distance L5 from the outer end in the tire axial direction to the first tread end Te1 is preferably 0.10 to 0.20 times the tread width TW.

  The outer joint groove 18 extends linearly, for example. For example, the outer joint groove 18 is preferably inclined in the opposite direction to the inclined groove 10. In other words, the outer joint groove 18 is inclined in the same direction as the intermediate joint groove 17. The outer joint groove 18 preferably has an angle θ7 with respect to the tire circumferential direction larger than that of the intermediate joint groove 17, for example. More specifically, the angle θ7 of the outer joint groove 18 is at least larger than the angle θ5 (shown in FIG. 3) of the main inclined portion 21 of the intermediate joint groove 17. In a desirable mode, the angle θ7 of the outer joint groove 18 is larger than the angle θ4 of an imaginary straight line connecting both ends of the groove center line of the intermediate joint groove 17. Thereby, the block divided by the outer joint groove 18 is likely to be appropriately deformed in the tire circumferential direction. Therefore, when running on an icy snow road, the snow in the inclined groove 10 is further compacted, and excellent icy and snowy road performance is obtained.

  In order to exhibit the above-described effect while maintaining the steering stability on the dry road surface, in a further desirable mode, the outer joint groove 18 has a smaller angle with respect to the tire circumferential direction than the inner joint groove 16. The angle θ7 of the outer joint groove 18 is preferably 60 to 70 °, for example.

  Each of the joint grooves 16 to 18 described above preferably has a groove width W2 that is 0.20 to 0.30 times the maximum groove width W1 of the inclined groove 10, for example. Each of the joint grooves 16 to 18 can improve the steering stability on the dry road surface and the ice / snow road performance in a well-balanced manner.

  FIG. 4 is a cross-sectional view of the outer joint groove 18 taken along the line AA as a diagram showing the cross-sectional shape of the joint groove 15. As shown in FIG. 4, it is desirable that the joint groove 15 has a maximum depth d2 that is, for example, 0.55 to 0.70 times the depth d1 of the inclined groove 10.

  In a desirable mode, it is desirable that the bottom surface of the joint groove 15 is raised at both end portions 15a in the tire axial direction. The depth d3 of the end portion 15a is preferably 0.65 to 0.80 times the maximum depth d2 of the joint groove 15, for example. Such a joint groove 15 can further enhance the steering stability on the dry road surface.

  A more detailed configuration of each groove will be described. FIG. 5 shows an enlarged view of the contours of the inclined groove 10, the central lateral groove 12 and the joint groove 15. As shown in FIG. 5, the intersection of the groove center line of the inclined groove 10 and the extended line of the groove center line of the outer joint groove 18 connected to the first arrival side in the rotation direction R of the inclined groove 10 is the first intersection 26. It is said. In order to improve the steering stability on the dry road surface and the snowy and snowy road performance with a good balance, the first distance L6 in the tire axial direction between the first tread end Te1 and the first intersection 26 is, for example, 0 of the tread width TW. It is desirable that it is 24 to 0.30 times.

  The intersection point between the groove center line of the inclined groove 10 and the extended line of the groove center line of the first intermediate joint groove 17A connected to the first arrival side of the inclined groove 10 in the rotation direction R is defined as a second intersection point 27. The second distance L7 in the tire axial direction between the first intersection 26 and the second intersection 27 is preferably, for example, 0.10 to 0.17 times the tread width TW.

  The intersection point between the extension line of the groove center line of the first central lateral groove 12A and the groove center line of the second inclined groove 10B is defined as a third intersection point 28. The third distance L8 in the tire axial direction between the second intersection point 27 and the third intersection point 28 is preferably, for example, 0.12 to 0.19 times the tread width TW.

  The first straight line 31 extending from the intersection 10e between the first tread end Te1 and the groove center line of the inclined groove 10 to the first intersection 26 is inclined, for example, at an angle θ8 of 5 to 25 ° with respect to the tire axial direction. Is desirable. As a result, the inclined groove 10 can form a long snow column in the tire axial direction, particularly in the vicinity of the first tread end Te1, thereby obtaining a large snow traction.

  The second straight line 32 extending from the second intersection point 27 to the third intersection point 28 is preferably inclined, for example, at an angle θ9 of 32 to 52 ° with respect to the tire axial direction.

  The intersection point between the groove center line of the inclined groove 10 and the extended line of the groove center line of the central lateral groove 12 that is continuous to the tire equator C side of the inclined groove 10 is a fourth intersection point 29. The third straight line 33 extending from the second intersection point 27 to the fourth intersection point 29 is preferably inclined at an angle θ10 of 51 to 71 ° with respect to the tire axial direction, for example.

  FIG. 6 shows an enlarged view of the inclined land portion 13. As shown in FIG. 6, the inclined land portion 13 is divided including, for example, a crown block 35, a plurality of middle blocks 36, and a shoulder block 37.

  The crown block 35 includes, for example, a region partitioned by the inner joint groove 16 and the inclined grooves 10 on both sides, and a region partitioned between the first central lateral groove 12A and the second central lateral groove 12B. The crown block 35 of the present embodiment has, for example, a tread surface surrounded by the first end edge 35a, the second end edge 35b, and the third end edge 35c. The first end edge 35a is, for example, in the rotational direction. It is convex on the first arrival side of R. The second end edge 35b is, for example, arranged on the rear arrival side of the rotation direction R with respect to the first end edge 35a, and is recessed on the first arrival side. The third end edge 35c connects the first end edge 35a and the second end edge 35b. Thereby, the crown block 35 has a substantially U-shaped tread surface.

  The crown block 35 is preferably provided with at least one crown lug sipe 38, for example. The crown lag sipe 38 has, for example, one end communicating with one of the grooves and the other end interrupted in the block. The crown lag sipe 38 extends, for example, in the tire axial direction. Such a crown lug sipe 38 can provide a frictional force, for example, on a hard-pressed snow road surface while maintaining the rigidity of the crown block 35. In the present specification, sipe means a cut having a width of less than 1.5 mm.

  The middle block 36 includes, for example, a first middle block 36A, a second middle block 36B, and a third middle block 36C. For example, the first middle block 36A is divided between the inner joint groove 16 and the first intermediate joint groove 17A. For example, the second middle block 36B is divided between the first intermediate joint groove 17A and the second intermediate joint groove 17B. For example, the third middle block 36C is divided between the second intermediate joint groove 17B and the outer joint groove 18.

  Each middle block 36 is preferably provided with, for example, a middle sipe 39 that completely crosses the block. Each middle sipe 39 of this embodiment is inclined in the same direction as the intermediate joint groove 17, for example.

  The shoulder block 37 is divided, for example, between the outer joint groove 18 and the first tread end Te1. The shoulder block 37 is provided with an outer lug groove 40 and a plurality of shoulder sipes 41, for example.

  For example, the outer lug groove 40 extends from one of the adjacent inclined grooves 10 and is interrupted in the inclined land portion 13. Such an outer lug groove 40 can improve the snow and snow road performance while maintaining the rigidity of the shoulder block 37.

  For example, the outer lug groove 40 is inclined in the same direction as the outer joint groove 18 and extends linearly. The outer lug groove 40 of the present embodiment extends, for example, along the outer joint groove 18. Such an outer lug groove 40 serves to make the rigidity distribution of the shoulder block 37 uniform and maintain steering stability on a dry road surface.

  For example, the outer lug groove 40 preferably overlaps with the outer joint groove 18 in the tire axial direction. Thereby, snow traction is further enhanced.

  FIG. 7 shows a cross-sectional view of the outer lug groove 40 taken along the line BB. As shown in FIG. 7, the outer lug groove 40 has, for example, a maximum depth d4 that is 0.50 to 0.65 times the depth d1 of the inclined groove 10.

  It is desirable that the outer lug groove 40 has a raised bottom surface, for example, at an end portion 40a continuous with the inclined groove 10. The depth d5 of the end portion 40a is preferably, for example, 0.65 to 0.75 times the maximum depth d4. Such an outer lug groove 40 can maintain the rigidity of the shoulder block 37, and as a result, can improve the driving stability on the dry road surface.

  As shown in FIG. 6, the shoulder sipe 41 includes, for example, a first shoulder sipe 41A and a second shoulder sipe 41B. For example, the first shoulder sipe 41A is provided between the outer joint groove 18 and the outer lug groove 40, and completely crosses the block. The first shoulder sipe 41A is inclined, for example, in the same direction as the outer joint groove 18, and extends along the outer joint groove 18 in the present embodiment.

  For example, one end of the second shoulder sipe 41B is connected to the inclined groove 10, and the other end extends to the first tread end Te1. Such a second shoulder sipe 41B can moderately reduce the rigidity of the shoulder block 37 and enhance the wandering performance.

  The second shoulder sipe 41B desirably includes, for example, an inclined sipe portion 43 and a horizontal sipe portion 44. For example, the inclined sipe portion 43 extends obliquely from the inclined groove 10. For example, the inclined sipe portion 43 is inclined in the same direction as the outer lug groove 40 and extends along the outer lug groove 40 in the present embodiment. It is desirable that the inclined sipe part 43 extends in a zigzag shape, for example. The inclined sipe portion 43 can maintain the apparent rigidity of the shoulder block 37 by engaging the sipe walls during tire traveling.

  The lateral sipe portion 44 is connected to the outer side in the tire axial direction of the inclined sipe portion 43 and extends to the first tread end Te1 along the tire axial direction. The horizontal sipe portion 44 extends, for example, linearly. In the second shoulder sipe 41B, the lateral sipe portion 44 allows shear deformation in the tire axial direction of the shoulder block 37 even if the sipe walls contact each other. For this reason, it becomes easy to discharge snow from the inclined groove 10 when traveling on an icy and snowy road.

  In the present embodiment, it is desirable that the sipe provided in each block is formed in a zigzag shape except for the lateral sipe portion 44 of the second shoulder sipe 41B. Such a sipe can maintain the apparent rigidity of each block, and as a result, can improve the steering stability on the dry road surface.

  As shown in FIG. 1, the land ratio Lr of the tread portion 2 of the present embodiment is preferably 60% or more, more preferably 65% or more, preferably 80% or less, more preferably 75% or less. . Thereby, the steering stability on the dry road surface and the snowy and snowy road performance are improved in a well-balanced manner. In this specification, the “land ratio” is a ratio Sb / Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact surface in which each groove and sipe are all filled.

  From the same viewpoint, the rubber hardness Ht of the tread rubber forming the tread portion 2 is preferably 45 ° or more, more preferably 55 ° or more, preferably 70 ° or less, more preferably 65 ° or less. In the present specification, the “rubber hardness” is hardness according to durometer type A in an environment of 23 ° C. in accordance with JIS-K6253.

  8 and 9 are developed views of the tread portion 2 of the tire 1 according to another embodiment of the present invention. 8 and 9, elements common to the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted here.

  In the embodiment shown in FIG. 8, each joint groove 15 extends linearly. In such an embodiment, since each joint groove 15 exhibits excellent drainage performance, for example, excellent performance can be exhibited on a road surface in which snow and water are mixed.

  In the embodiment shown in FIG. 9, not only the intermediate joint groove 17 but also the inner joint groove 16 and the outer joint groove 18 have two bent portions that protrude in opposite directions. Such an inner joint groove 16 and an outer joint groove 18 help to form a hard snow column, and as a result, the performance of ice and snow roads is improved.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, and can be carried out by changing to various modes.

A pneumatic tire of size 205 / 55R16 having the basic tread pattern of FIG. 1 was manufactured based on the specifications in Table 1. As a comparative example, as shown in FIG. 10, a tire in which the groove width of the central lateral groove is smaller than the groove width of the inner joint groove was experimentally manufactured. The test stability of each test tire on the dry road surface and the snow / ice road performance were tested. The common specifications and test methods for each test tire are as follows.
Tread contact width: 160mm
Groove depth of inclined groove: 8.5mm
Land ratio: 70%
Tread rubber hardness Ht: 65
Rims: 16 x 6.5
Tire internal pressure: 200kPa
Test vehicle: 2000cc displacement, front-wheel drive vehicle Test tire mounting position: all wheels

<Operation stability on dry road>
The driving stability of the test vehicle when traveling on a dry road course was evaluated by the driver's sensuality. A result is a score which makes a comparative example 100, and shows that the steering stability on a dry road surface is excellent, so that a numerical value is large.

<Ice and snow road performance>
The driving performance when driving on an icy and snowy road with the test vehicle was evaluated by the driver's sensuality. A result is a score which makes the comparative example 100, and shows that the snowy and snowy road performance is excellent, so that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tires of the examples exhibited excellent icy and snowy road performance and driving stability on dry road surfaces.

2 Tread portion 10 Inclined groove 12 Central lateral groove 13 Inclined land portion 15 Joint groove C Tire equator Te1 First tread end

Claims (7)

A tire having a tread portion,
The tread portion includes a plurality of inclined grooves extending obliquely from the first tread end on one side in the tire axial direction toward the tire equator and interrupted between the tire equator and the first tread end, and the tire equator. A plurality of central lateral grooves that cross each other and communicate with the plurality of inclined grooves, and a plurality of inclined land portions divided between the inclined grooves adjacent in the tire circumferential direction are provided,
The inclined land portion is provided with a connecting groove communicating between the inclined grooves,
The central lateral groove has a larger groove width than the joint groove.
tire. The inclined land portion is provided with a plurality of the joint grooves,
The plurality of joint grooves include an inner joint groove provided on the most tire equator side,
The tire according to claim 1, wherein the central lateral groove has a groove width that is larger than a maximum groove width of the inner joint groove over the entire length thereof.   The tire according to claim 2, wherein the central lateral groove and the inner joint groove communicate with the same position of the inclined groove.   The tire according to claim 2 or 3, wherein an angle of the inner joint groove with respect to the tire axial direction is smaller than an angle of the central lateral groove with respect to the tire axial direction.   The tire according to claim 4, wherein a difference between an angle of the central lateral groove with respect to the tire axial direction and an angle of the inner joint groove with respect to the tire axial direction is 20 ° or less.   The tire according to any one of claims 1 to 5, wherein each of the plurality of central lateral grooves is inclined at an angle of 5 to 25 degrees with respect to a tire axial direction.   The tire according to any one of claims 1 to 6, wherein the inclined groove has an inner end portion on a tire equator side that is interrupted without being connected to another groove.

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