tire

Abstract

To provide a tire which can exhibit excellent on-snow performance while maintaining dry performance.SOLUTION: A tire has a tread part 2 with a designated rotation direction R. The tread part 2 includes a first tread end T1 and a second tread end T2. The tread part 2 is provided with: a plurality of first inclined grooves 6 which extend toward a tire equator C side from the first tread end T1 so as to be inclined to a side of the rotation direction R; a plurality of second inclined grooves 7 which extend toward the tire equator side from the second tread end T2 so as to be inclined to the side of the rotation direction R; and a first vertical groove 9 which communicates between two first inclined grooves 6 which are adjacent to each other in a tire circumferential direction. An end of the first inclined groove 6 on the tire equator C side communicates with the second inclined groove 7. An end of the second inclined groove 7 on the tire equator C side communicates with the first inclined groove 6. The first vertical groove 9 has a groove width that becomes larger toward the rotation direction R.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire. [Background technology]

[0002] Various tires suitable for driving on snow have been proposed in the past. For example, the following Patent Document 1 proposes a tire provided with a plurality of first inclined grooves and connecting grooves connecting the first inclined grooves. The first inclined grooves extend obliquely from a first tread edge on one side in the tire axial direction toward the tire equator side, and are discontinued without connecting to other grooves. The connecting groove extends between the two first inclined grooves with a constant groove width. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-193056 A Summary of the Invention [Problem to be solved by the invention]

[0004] As vehicles become more powerful, there is a demand for tires to have better snow performance. In general, one method of improving snow performance is to increase the volume of the grooves in the tread. However, this method may result in a decrease in dry performance, which is the driving performance on dry roads.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that can exhibit excellent performance on snow while maintaining dry performance. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion with a specified rotational direction, the tread portion including a first tread edge and a second tread edge, the tread portion being provided with a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator side with an inclination toward the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator side with an inclination toward the rotational direction, and a first longitudinal groove connecting two of the first inclined grooves adjacent to each other in the tire circumferential direction, the end of the first inclined groove on the tire equator side being connected to the second inclined groove, the end of the second inclined groove on the tire equator side being connected to the first inclined groove, and the groove width of the first longitudinal groove becoming larger toward the rotational direction.

[0007] In the tire of the present invention, it is preferable that the groove width of the first longitudinal groove continuously increases in the rotational direction.

[0008] In the tire of the present invention, it is preferable that the first longitudinal groove is inclined in a direction opposite to that of the first inclined groove with respect to the tire axial direction.

[0009] In the tire of the present invention, it is preferable that an angle of the first inclined groove with respect to the tire axial direction increases toward the tire equator.

[0010] In the tire of the present invention, it is preferable that the first inclined groove includes a plurality of linear groove portions extending linearly and inclined with respect to the tire axial direction.

[0011] In the tire of the present invention, it is preferable that the first inclined groove includes a first straight groove portion extending linearly and inclined from at least the first tread end in the tire axial direction, and a second straight groove portion connected to the first straight groove portion and extending linearly at a larger angle with respect to the tire axial direction than the first straight groove portion, and that at least one end of the first longitudinal groove is connected to the second straight groove portion.

[0012] In the tire of the present invention, it is preferable that the tread portion is provided with a plurality of longitudinal shallow grooves that communicate between two of the first oblique grooves adjacent to each other in the tire circumferential direction and have a depth smaller than that of the first longitudinal grooves.

[0013] In the tire of the present invention, it is preferable that the longitudinal shallow groove has a groove width increasing in a direction opposite to that of the first longitudinal groove.

[0014] In the tire of the present invention, it is preferable that the longitudinal shallow groove includes a first portion having a constant groove width and a second portion in which the groove width increases in the direction opposite to the rotational direction.

[0015] In the tire of the present invention, it is preferable that the tread portion includes a central land portion between the two first inclined grooves and sectioned on the tire equator side of the first longitudinal groove, the central land portion includes a plurality of block pieces that connect the two first inclined grooves and are sectioned into at least one longitudinal shallow groove having a depth smaller than that of the first longitudinal groove, and the plurality of block pieces include a crown block piece that is sectioned closest to the tire equator side and a middle block piece that is arranged on the first tread end side of the crown block piece.

[0016] In the tire of the present invention, it is preferable that the crown block piece is provided with a plurality of crown sipes extending along the tire axial direction.

[0017] In the tire of the present invention, it is preferable that the middle block piece is provided with a plurality of middle sipes inclined in a direction opposite to that of the first inclined groove with respect to the tire axial direction. Effect of the Invention

[0018] By adopting the above-mentioned configuration, the tire of the present invention can exhibit excellent performance on snow while maintaining dry performance. [Brief description of the drawings]

[0019] [Figure 1] 1 is a development view of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of the contour of the first inclined groove of FIG. 1; [Diagram 3] 3 is a cross-sectional view taken along the length direction of a fourth straight groove portion of FIG. 2. FIG. [Figure 4] FIG. 2 is an enlarged view of the first longitudinal groove of FIG. [Diagram 5] FIG. 2 is an enlarged view of the central land portion and the outer land portion of FIG. [Figure 6] FIG. 2 is a development view of a tread portion of a tire of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 according to this embodiment (hereinafter, may be simply referred to as a "tire"). As shown in Fig. 1, the tire 1 according to this embodiment is, for example, a pneumatic tire for winter use, and is preferably for passenger cars. However, the tire 1 of the present invention is not limited to such an embodiment.

[0021] The tire 1 of the present embodiment has, for example, a directional pattern in which a rotational direction R is specified. The rotational direction R is indicated, for example, by letters or symbols on a sidewall portion (not shown).

[0022] The tread portion 2 of the tire 1 of this embodiment includes a first tread edge T1 and a second tread edge T2. The tread portion 2 also includes a first tread portion 2A between the tire equator C and the first tread edge T1, and a second tread portion 2B between the tire equator C and the second tread edge T2. The first tread portion 2A and the second tread portion 2B are substantially configured to be line-symmetrical about the tire equator C, except that they are misaligned in the tire circumferential direction. Therefore, at least each configuration of the first tread portion 2A described below can be applied to the second tread portion 2B.

[0023] The first tread edge T1 and the second tread edge T2 are the axially outermost contact points when the tire 1 in a normal state is loaded with a normal load and contacts a flat surface with a camber angle of 0°.

[0024] "Normal condition" means, in the case of a pneumatic tire for which various standards are established, that the tire is mounted on a normal rim, inflated to the normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established or a non-pneumatic tire, the normal condition means a standard use condition according to the intended use of the tire, and a state in which no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal condition.

[0025] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "Design Rim," and in the case of ETRTO, it is called a "Measuring Rim."

[0026] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system on which the tire is based. In the case of JATMA, it is the "maximum air pressure." In the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." In the case of ETRTO, it is the "INFLATION PRESSURE."

[0027] In the case of a pneumatic tire for which various standards are established, the "normal load" is the load that each standard specifies for each tire in the standard system including the standard on which the tire is based. For JATMA, it is the "maximum load capacity", for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is the "LOAD CAPACITY". In addition, in the case of a tire for which various standards are not established or a non-pneumatic tire, the "normal load" refers to the load acting on one tire in the standard mounting state of the tire. The "standard mounting state" refers to a state in which the tire is mounted on a standard vehicle according to the intended use of the tire, and the vehicle is stationary on a flat road surface in a drivable state.

[0028] The tread portion 2 is provided with a plurality of first inclined grooves 6 and a plurality of second inclined grooves 7. The first inclined grooves 6 extend at least from the first tread edge T1 toward the tire equator C with an inclination toward the rotational direction R. The second inclined grooves 7 extend at least from the second tread edge T2 toward the tire equator C with an inclination toward the rotational direction R. In addition, the tread portion 2 is provided with a first longitudinal groove 9 that communicates between the two first inclined grooves 6.

[0029] The end of the first inclined groove 6 on the tire equator C side is connected to the second inclined groove 7. The end of the second inclined groove 7 on the tire equator C side is connected to the first inclined groove 6. The first longitudinal groove 9 has a groove width that increases in the rotational direction R. By adopting the above-mentioned configuration, the tire of the present invention can exhibit excellent performance on snow while maintaining dry performance. The following mechanism is presumed to be the reason for this.

[0030] In the tire 1 of the present invention, the end of the first inclined groove 6 on the tire equator C side is connected to the second inclined groove 7, and the end of the second inclined groove 7 on the tire equator C side is connected to the first inclined groove 6, so that a solid snow pillar can be formed at the connecting part of the inclined grooves, and by shearing this, a large reaction force (hereinafter sometimes referred to as snow pillar shear force) can be obtained.

[0031] In addition, since the groove width of the first longitudinal grooves 9 increases in the rotational direction R, the rotation of the tire can be used to firmly compress the snow pillars within the first longitudinal grooves 9 in the groove length direction, resulting in a larger snow pillar shear force.

[0032] The above-mentioned effects can be obtained without depending on an increase in groove volume. Therefore, dry performance can be maintained. It is presumed that this mechanism allows the present invention to exhibit excellent on-snow performance while maintaining dry performance.

[0033] A more detailed configuration of this embodiment will be described below. Each configuration described below shows a specific aspect of this embodiment. Therefore, it goes without saying that the present invention can achieve the above-mentioned effects even if it does not have the configuration described below. In addition, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-mentioned characteristics, an improvement in performance according to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a composite improvement in performance according to each configuration can be expected.

[0034] Fig. 2 shows an enlarged view of the outline of the first inclined groove 6 in Fig. 1. Note that sipes arranged in the land portion are omitted in Fig. 2. As shown in Fig. 2, the first inclined groove 6 includes, for example, a transverse first inclined groove 6a that crosses the tire equator C, and a non-transverse first inclined groove 6b that does not cross the tire equator C and communicates with the second inclined groove 7.

[0035] For example, the angle of the first inclined grooves 6 with respect to the tire axial direction becomes larger toward the tire equator C. Such first inclined grooves 6 provide snow column shear forces in multiple directions, which helps to improve traction performance and cornering performance on snow.

[0036] The first inclined groove 6 desirably includes a plurality of straight groove portions 10 that extend linearly and inclined with respect to the tire axial direction. In a more preferable embodiment, the first inclined groove 6 of the present embodiment is composed of a plurality of straight groove portions 10 and does not include a curved groove edge. Compared to an inclined groove composed of curved groove edges, such a first inclined groove 6 can increase the area of ​​the land portion while maintaining the frictional force generated by the groove edge.

[0037] The first inclined groove 6 includes, for example, a first straight groove portion 11, a second straight groove portion 12, a third straight groove portion 13, and a fourth straight groove portion 14. The first straight groove portion 11 extends linearly, for example, from at least the first tread edge T1 at an angle in the tire axial direction. The second straight groove portion 12 is continuous with the first straight groove portion 11 and extends linearly at a larger angle with respect to the tire axial direction than the first straight groove portion 11. The third straight groove portion 13 is continuous with the second straight groove portion 12 and extends linearly at a larger angle with respect to the tire axial direction than the second straight groove portion. The fourth straight groove portion 14 is continuous with the third straight groove portion 13 and extends linearly at a larger angle with respect to the tire axial direction than the third straight groove portion 13.

[0038] The angle of the first straight groove portion 11 with respect to the tire axial direction is, for example, 5 to 15°. The length of the first straight groove portion 11 (the so-called periphery length along the length direction of the groove) is 25% to 40% of the total length of the first inclined groove 6 from the first tread edge T1 to the end on the tire equator C side (also the periphery length). Hereinafter, in this specification, unless otherwise specified, the length of a groove or groove portion refers to the so-called periphery length along its length direction.

[0039] The angle of the second straight groove portions 12 with respect to the tire axial direction is, for example, 30 to 40°. The length of the second straight groove portions 12 is shorter than the length of the first straight groove portions 11, and is, for example, 15% to 30% of the total length of the first inclined grooves 6.

[0040] The angle of the third straight groove portions 13 with respect to the tire axial direction is, for example, 50 to 60°. The length of the third straight groove portions 13 is greater than the length of the second straight groove portions 12, and is, for example, 25% to 40% of the total length of the first inclined grooves 6.

[0041] The angle of the fourth straight groove portion 14 with respect to the tire axial direction is, for example, 55 to 65°. The length of the fourth straight groove portion 14 is shorter than the length of the third straight groove portion 13, and is, for example, 5% to 15% of the total length of the first inclined groove 6.

[0042] The traction performance and turning performance on snow can be improved in a well-balanced manner by the above-mentioned arrangement of the straight groove portions 10. However, the first inclined grooves 6 are not limited to such an arrangement of the straight groove portions 10.

[0043] The first linear groove portion 11 extends with a constant groove width, for example. The groove width W1 of the first linear groove portion 11 is, for example, 3.0% to 6.0% of the tread width TW (shown in FIG. 1). Such a first linear groove portion 11 helps to improve performance on snow while maintaining dry performance. The tread width TW is the axial distance from the first tread edge T1 to the second tread edge T2 in the normal state.

[0044] The groove width of the first inclined grooves 6 decreases from the second straight groove portion 12 toward the fourth straight groove portion 14. The groove width of the first inclined grooves 6 at the end portion on the tire equator C side is 25% to 50% of the groove width W1 of the first straight groove portion 11. This increases the rigidity of the tread portion 2 in the vicinity of the tire equator C, improving dry performance.

[0045] In addition, the groove width of the transverse first inclined groove 6a at the end portion on the tire equator C side is smaller than the groove width of the non-transverse first inclined groove 6b at the end portion on the tire equator C side. This makes it easier to disperse the frequency band of noise generated by the first inclined groove 6, improving noise performance.

[0046] In order to enhance the above-mentioned effect, the length of the third straight groove portion 13 of the transverse first inclined groove 6a is greater than the length of the third straight groove portion 13 of the non-transverse first inclined groove 6b. Also, the groove width of the third straight groove portion 13 of the transverse first inclined groove 6a decreases toward the tire equator C. In contrast, the third straight groove portion 13 of the non-transverse first inclined groove 6b extends with a constant groove width.

[0047] FIG. 3 shows a cross-sectional view along the length of the fourth straight groove portion 14 of this embodiment. As shown in FIG. 3, the fourth straight groove portion 14 desirably includes a raised portion 19 whose depth decreases toward the end of the first inclined groove 6 on the tire equator C side. The raised portion 19 includes, for example, a bottom surface that extends at an incline with respect to the ground contact surface of the tread portion 2. The length of the raised portion 19 is, for example, 5% to 15% of the length of the first inclined groove 6. The minimum depth d1 of the raised portion 19 is, for example, 20% to 40% of the maximum depth of the fourth straight groove portion 14. Such a raised portion 19 increases the rigidity of the tread portion 2 near the tire equator C to improve dry performance, and is useful for suppressing snow from clogging in the first inclined groove 6.

[0048] As shown in FIG. 1, a distance L1 in the tire axial direction from the tire equator C to the first longitudinal groove 9 is, for example, 20% to 30% of the tread width TW.

[0049] 2, the first longitudinal grooves 9 are inclined in the opposite direction to the first inclined grooves 6 with respect to the tire axial direction. The angle of the first longitudinal grooves 9 with respect to the tire axial direction is, for example, larger than the angle of the fourth straight groove portions 14 with respect to the tire axial direction, and is, for example, 80 to 90°. Such first longitudinal grooves 9 are useful for improving cornering performance on snow.

[0050] It is desirable that at least one end of the first vertical groove 9 communicates with the second straight groove portion 12. More specifically, an end 9a of the first vertical groove 9 on the rotation direction R side communicates with the first straight groove portion 11 and the second straight groove portion 12 of the first inclined groove 6 so as to straddle them, and an end 9b of the first vertical groove 9 on the opposite side of the rotation direction R communicates with the second straight groove portion 12 of the first inclined groove 6.

[0051] Fig. 4 shows an enlarged view of the first vertical groove 9. As shown in Fig. 4, it is desirable that the groove width of the first vertical groove 9 continuously increases in the rotational direction R. This makes it easier for snow to be compacted inside the first vertical groove 9.

[0052] The first opening width W2 of the first longitudinal groove 9 relative to the first inclined groove 6 on the side of the rotation direction R is preferably 120% or more, more preferably 125% or more, and preferably 140% or less, more preferably 135% or less of the second opening width W3 of the first longitudinal groove 9 relative to the first inclined groove 6 on the opposite side of the rotation direction R of the first longitudinal groove 9. The angle θ1 between one groove edge and the other groove edge of the first longitudinal groove 9 is 3 to 7°. This allows the first longitudinal groove 9 to form a hard snow column while maintaining the rigidity of the land portion around the first longitudinal groove 9. Therefore, the on-snow performance is improved while maintaining the dry performance.

[0053] In order to further enhance the above-mentioned effects, it is desirable that the first opening width W2 and the second opening width W3 are larger than the groove width of the third straight groove portion 13 and the groove width of the second straight groove portion 12. In addition, it is desirable that the second opening width W3 is smaller than the groove width of the first straight groove portion 11.

[0054] As shown in Fig. 2, the tread portion 2 is provided with a plurality of longitudinal shallow grooves 20 that communicate between two adjacent first inclined grooves 6 in the tire circumferential direction and have a depth smaller than that of the first longitudinal groove 9. The depth of the longitudinal shallow grooves 20 is, for example, half or less of the depth of the first longitudinal groove 9. Specifically, the depth of the longitudinal shallow grooves 20 is preferably 25% or more, more preferably 30% or more, and preferably 40% or less, more preferably 35% or less of the depth of the first longitudinal groove 9. Such longitudinal shallow grooves 20 improve the dry performance and the on-snow performance in a well-balanced manner.

[0055] The longitudinal shallow groove 20 has a groove width that increases in the opposite direction to the first longitudinal groove 9. In this embodiment, the longitudinal shallow groove 20 includes a first portion 20a having a constant groove width and a second portion 20b whose groove width increases in the opposite direction to the rotational direction R. The second portion 20b is connected to the opposite side of the rotational direction R to the first portion 20a. Such a longitudinal shallow groove 20 allows snow to be easily discharged from the second portion 20b side, and can prevent snow from clogging inside.

[0056] The opening width W5 of the first inclined groove 6 in the second portion 20b is 1.5 to 2.5 times the groove width W4 of the first portion 20a. The length of the second portion 20b is, for example, half or less of the total length of the longitudinal shallow groove 20, and preferably 20% to 30% of the total length of the longitudinal shallow groove 20.

[0057] The longitudinal shallow grooves 20 include an outer longitudinal shallow groove 21 arranged closer to the first tread edge T1 than the first longitudinal groove 9, and an inner longitudinal shallow groove 22 arranged closer to the tire equator C than the first longitudinal groove 9. In this embodiment, one outer longitudinal shallow groove 21 is arranged between two first oblique grooves 6, and one or two inner longitudinal shallow grooves 22 are arranged.

[0058] As shown in FIG. 1, the tread portion 2 includes a central land portion 25 between the two first inclined grooves 6 and positioned closer to the tire equator C than the first longitudinal groove 9, and an outer land portion 26 between the two first inclined grooves 6 and positioned closer to the first tread end T1 than the first longitudinal groove 9.

[0059] Fig. 5 shows an enlarged view of the central land portion 25 and the outer land portion 26. As shown in Fig. 5, the central land portion 25 includes a plurality of block pieces divided into at least one longitudinal shallow groove 20. The plurality of block pieces include a crown block piece 27 divided closest to the tire equator C, and a middle block piece 28 arranged closer to the first tread edge T1 than the crown block piece 27.

[0060] The central land portion 25 in this embodiment includes a first central land portion 25a constituted by one crown block piece 27 and one middle block piece 28 by arranging one vertical shallow groove 20, and a second central land portion 25b constituted by one crown block piece 27 and two middle block pieces 28 by arranging two vertical shallow grooves 20.

[0061] Each block piece is provided with a plurality of sipes. Each sipe of this embodiment extends, for example, in a zigzag shape in a plan view of the tread. Each sipe may extend linearly. In this specification, the term "sipe" refers to a cut element having a small width, and the width between two inner walls is 1.5 mm or less. The width of the sipe is preferably 0.2 to 1.2 mm, more preferably 0.5 to 1.0 mm. The width of the sipe of this embodiment is within the above range throughout its entire depth direction. The sipe may be connected to a chamfered opening or a flask bottom having a width larger than the above range.

[0062] The crown block piece 27 is provided with a plurality of crown sipes 31 extending along the tire axial direction. The crown sipes 31 are arranged such that, for example, an imaginary line connecting both ends of the crown sipes 31 forms an angle of 5° or less with respect to the tire axial direction. The edges of such crown sipes 31 provide a large frictional force in the tire circumferential direction.

[0063] The middle block piece 28 is provided with a plurality of middle sipes 32. The middle sipes 32 are inclined, for example, in the opposite direction to the first inclined grooves 6 with respect to the tire axial direction. The angle of the imaginary line connecting both ends of the middle sipes 32 with respect to the tire axial direction is smaller than the angles of the first longitudinal grooves 9 and the longitudinal shallow grooves 20 with respect to the tire axial direction, and is, for example, 40 to 50°. Such middle sipes 32 improve traction performance and cornering performance on snow in a well-balanced manner.

[0064] The outer land portion 26 is provided with a plurality of outer sipes 33. The outer sipes 33 are inclined, for example, in the same direction as the first inclined grooves 6 with respect to the tire axial direction. In a desirable embodiment, the angle difference between an imaginary line connecting both ends of the outer sipes 33 and the first straight groove portion 11 is set to 5° or less. Moreover, the angle of the imaginary line with respect to the tire axial direction is set to, for example, 5 to 15°.

[0065] In order to improve the dry performance and the performance on snow in a well-balanced manner, the land ratio Lr of the tread portion 2 of this embodiment is desirably, for example, 55% to 70%, as shown in Fig. 1. In this specification, the "land ratio" refers to the ratio Sb / Sa of the actual total contact area Sb to the total area Sa of the virtual contact area in which all the grooves and sipes are filled.

[0066] From the same viewpoint, it is desirable that the rubber hardness Ht of the tread rubber forming the tread portion 2 is, for example, 45 to 65°. In this specification, the "rubber hardness" is a hardness measured by a durometer type A in an environment of 23°C in accordance with JIS-K6253.

[0067] Although the tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and can be modified and carried out in various aspects. EXAMPLES

[0068] Pneumatic tires of size 205 / 55R16 having the basic tread pattern of FIG. 1 were prototyped based on the specifications of Table 1. As a comparative example, a tire in which the first longitudinal grooves a extend with a constant groove width as shown in FIG. 6 was prototyped. The comparative tire was substantially the same as the tire shown in FIG. 1 except for the above-mentioned points. The dry performance and snow performance of each test tire were tested. The common specifications and test methods of each test tire are as follows. Test vehicle: 2000cc displacement, front-wheel drive Test tire mounting position: All wheels Rim: 16×6.5 Tire pressure: Front wheel 240kPa, rear wheel 220kPa

[0069] <Dry performance> The driving performance of the test vehicle when it was driven on a dry road surface was evaluated by the driver. The results are given as a score based on the comparative example being 100, with a higher score indicating better dry performance.

[0070] <Snow performance> The driving performance of the test vehicle when it was driven on snowy roads was evaluated by the driver. The results are given as a score based on the comparative example being 100, with a higher score indicating better performance on snow. The test results are shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, the test results confirmed that the tires of the examples exhibited excellent performance on snow while maintaining dry performance. [Explanation of symbols]

[0073] 2 Tread section 6 1st inclined groove 7 2nd inclined groove 9 First vertical groove T1 First tread edge T2 Second tread edge R Rotation direction

Claims

1. A tire having a tread portion with a specified rotation direction, The tread portion includes a first tread edge and a second tread edge, The tread portion is provided with a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator at an incline toward the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator at an incline toward the rotational direction, and a first longitudinal groove communicating between two of the first inclined grooves adjacent to each other in the tire circumferential direction, An end portion of the first inclined groove on the tire equator side is connected to the second inclined groove, An end portion of the second inclined groove on the tire equator side is connected to the first inclined groove, The first longitudinal groove has a groove width that increases in the rotational direction, The first inclined grooves include a transverse first inclined groove that crosses the tire equator and a non-transverse first inclined groove that does not cross the tire equator and is connected to the second inclined groove, a groove width at an end portion of the transverse first inclined groove on the tire equator side is smaller than a groove width at an end portion of the non-transverse first inclined groove on the tire equator side; tire.

2. A tire as described in claim 1, wherein the tread portion has a plurality of shallow longitudinal grooves that connect two adjacent first inclined grooves in the tire circumferential direction and have a depth smaller than that of the first longitudinal grooves.

3. A tire having a tread portion with a specified rotation direction, The tread portion includes a first tread edge and a second tread edge, The tread portion is provided with a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator at an incline toward the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator at an incline toward the rotational direction, and a first longitudinal groove communicating between two of the first inclined grooves adjacent to each other in the tire circumferential direction, An end portion of the first inclined groove on the tire equator side is connected to the second inclined groove, An end portion of the second inclined groove on the tire equator side is connected to the first inclined groove, The first longitudinal groove has a groove width that increases in the rotational direction, The tread portion is provided with a plurality of longitudinal shallow grooves that communicate between two of the first inclined grooves adjacent to each other in the tire circumferential direction and have a depth smaller than that of the first longitudinal grooves, The longitudinal shallow groove has a groove width increasing in an opposite direction to the first longitudinal groove. tire.

4. A tire having a tread portion with a specified rotation direction, The tread portion includes a first tread edge and a second tread edge, The tread portion is provided with a plurality of first inclined grooves extending from at least the first tread edge toward the tire equator at an incline toward the rotational direction, a plurality of second inclined grooves extending from at least the second tread edge toward the tire equator at an incline toward the rotational direction, and a first longitudinal groove communicating between two of the first inclined grooves adjacent to each other in the tire circumferential direction, An end portion of the first inclined groove on the tire equator side is connected to the second inclined groove, An end portion of the second inclined groove on the tire equator side is connected to the first inclined groove, The first longitudinal groove has a groove width that increases in the rotational direction, The tread portion is provided with a plurality of longitudinal shallow grooves that communicate between two of the first inclined grooves adjacent to each other in the tire circumferential direction and have a depth smaller than that of the first longitudinal grooves, The longitudinal shallow groove includes a first portion having a constant groove width and a second portion whose groove width increases in a direction opposite to the rotation direction. tire.

5. A tire as described in any one of claims 1 to 4, wherein the groove width of the first longitudinal groove increases continuously in the rotational direction.

6. A tire as described in any one of claims 1 to 5, wherein the first longitudinal groove is inclined in a direction opposite to that of the first inclined groove with respect to the tire axial direction.

7. A tire as described in any one of claims 1 to 6, wherein the angle of the first inclined groove with respect to the tire axial direction increases toward the tire equator.

8. A tire as described in any one of claims 1 to 7, wherein the first inclined groove includes a plurality of straight groove portions extending linearly and inclined with respect to the tire axial direction.

9. The first inclined groove includes at least a first straight groove portion extending linearly from the first tread end at an incline in the tire axial direction, and a second straight groove portion connected to the first straight groove portion and extending linearly at an angle larger than that of the first straight groove portion with respect to the tire axial direction, The tire according to claim 1 , wherein at least one end of the first longitudinal groove is connected to the second linear groove portion.

10. the tread portion includes a central land portion that is partitioned between the two first inclined grooves and is located closer to the tire equator than the first longitudinal grooves, The central land portion includes a plurality of block pieces that communicate between the two first inclined grooves and are divided into at least one longitudinal shallow groove having a depth smaller than that of the first longitudinal groove, 10. The tire according to claim 1, wherein the plurality of block pieces include a crown block piece that is sectioned closest to the tire equator and a middle block piece that is arranged closer to the first tread end than the crown block piece.

11. The tire according to claim 10 , wherein the crown block piece is provided with a plurality of crown sipes extending axially along the tire.

12. The tire according to claim 10 or 11, wherein the middle block piece is provided with a plurality of middle sipes inclined in a direction opposite to the first inclined groove with respect to the tire axial direction.

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