pneumatic tires

Abstract

To provide a pneumatic tire that can enhance effect in enhancing drainage performance, while securing rigidity of lands.SOLUTION: The pneumatic tire comprises a plurality of main grooves extending in a tire circumferential direction provided in a tread, a plurality of lands partitioned by the plurality of main grooves, and oblique parts extending obliquely toward the adjacent main grooves from upper surfaces of the lands toward side surfaces thereof. The oblique parts comprise base parts extending along the adjacent main grooves and bending parts bending from the base parts toward the inside of the lands. Lengths in the tire circumferential direction of the bending parts are more than 30% and 70% or less of lengths in the tire circumferential direction of the oblique parts.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire.

Background Art

[0002] Patent Document 1 discloses a pneumatic tire comprising a plurality of main grooves extending in the tire circumferential direction, and lateral grooves extending from the main grooves in the tire axial direction, wherein inclined portions are provided on the groove wall surfaces of the main grooves and the lateral grooves, and the width of the inclined portion provided on the groove wall surface of the lateral groove gradually increases toward the main groove. Drainage performance and noise performance are improved by providing the inclined portion in the lateral groove.

[0003] However, when the inclined portion is provided, there is a possibility that the rigidity of the land portion cannot be ensured depending on the shape of the inclined portion. Further, when the rigidity of the land portion is ensured by changing the shape of the inclined portion, the effect of improving drainage performance may be reduced depending on the shape of the inclined portion.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] An object of the present disclosure is to provide a pneumatic tire capable of enhancing the effect of improving drainage performance while ensuring the rigidity of a land portion.

Means for Solving the Problem

[0006] The pneumatic tire of this disclosure comprises a plurality of main grooves extending in the circumferential direction of the tire provided in the tread, a plurality of land areas partitioned by the plurality of main grooves, and an inclined portion extending from the upper surface of the land area toward the adjacent main groove toward the side surface, wherein the inclined portion comprises a base portion extending along the adjacent main groove and a curved portion bending inward from the base portion toward the land area, and the length of the curved portion in the circumferential direction of the tire is greater than 30% and less than or equal to 70% of the length of the inclined portion in the circumferential direction of the tire. [Brief explanation of the drawing]

[0007] [Figure 1] Cross-sectional view of a pneumatic tire in the tire meridional plane according to one embodiment. [Figure 2] A perspective view showing the main part of the tread of a pneumatic tire according to the same embodiment. [Figure 3] This figure shows the tread pattern of a pneumatic tire according to the same embodiment. [Figure 4] Enlarged view of region IV in Figure 3 [Figure 5] Figure 4: Enlarged cross-sectional view of the VV line [Figure 6] Figure 3, enlarged cross-sectional view along line VI-VI [Figure 7] Figure 3, enlarged section view along line VII-VII [Figure 8] A diagram showing the main part of the tread pattern of a pneumatic tire according to another embodiment. [Figure 9] A diagram showing the main part of the tread pattern of a pneumatic tire according to another embodiment. [Figure 10] Enlarged cross-sectional view of line XX in Figure 9 [Modes for carrying out the invention]

[0008] The following describes one embodiment of a pneumatic tire with reference to Figures 1 to 7. Note that in each figure (and similarly in Figures 8 to 10), the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, nor do the dimensional ratios between the drawings necessarily match.

[0009] In each figure, the first direction D1 is the tire axis direction D1, which is parallel to the tire rotation axis of the pneumatic tire (hereinafter also simply referred to as "tire") 1; the second direction D2 is the tire radial direction D2, which is the diameter direction of tire 1; and the third direction D3 is the tire circumferential direction D3 around the tire rotation axis.

[0010] In the tire axial direction D1, the inner side is closer to the tire equatorial plane S1, and the outer side is further from the tire equatorial plane S1. In the tire radial direction D2, the inner side is closer to the tire rotation axis, and the outer side is further from the tire rotation axis. Furthermore, in the tire axial direction D1, one direction is called the first axial direction D11, and the other direction is called the second axial direction D12. In the tire circumferential direction D3, one direction is called the first circumferential direction D31, and the other direction is called the second circumferential direction D32.

[0011] The tire equatorial plane S1 is the plane perpendicular to the tire rotation axis and located at the center of the tire axial direction D1. The tire meridian plane is the plane that contains the tire rotation axis and is perpendicular to the tire equatorial plane S1. The tire equatorial line Ln is the line where the outer surface of the tire radially D2 intersects the tire equatorial plane S1.

[0012] As shown in Figure 1, the tire 1 comprises a pair of bead portions 11, 11, a pair of sidewalls 12, 12 extending outward from each bead portion 11, 11 in the tire radial direction D2, a tread 13 connected to the outer ends of the pair of sidewalls 12, 12 in the tire radial direction D2, a carcass ply 14 extending across the pair of bead portions 11, 11, and an inner liner 15 forming the innermost surface of the tire 1.

[0013] In this embodiment, tire 1 is a directional tire whose mounting direction to the vehicle is specified. Tire 1 is provided with, for example, a mark (letters, symbols, figures, etc.) that specifies the mounting direction. The mark is provided on the outer surface of tire 1 (for example, the side of tire 1 such as the sidewall 12). The first axial direction D11 indicates the outside of tire 1 when mounted on the vehicle, and the second axial direction D12 indicates the inside of tire 1 when mounted on the vehicle. Note that tire 1 is not limited to the above, and may also be, for example, a tire whose mounting direction is not specified or a directional tire whose rotation direction is specified.

[0014] As shown in Figures 1 to 3, the tire 1 is provided with a plurality of main grooves 2 extending in the tire circumferential direction D3 in the tread 13. The groove depth of the main grooves 2 is, for example, 7 mm to 15 mm. The groove depth of the main grooves 2 is the maximum value of the tire radial direction D2 from the outer surface of the tread 13 to the bottom of the main grooves 2. The main grooves 2 are formed in a continuous linear shape, but are not limited to this. For example, the main grooves 2 may be formed in a zigzag shape. In this embodiment, the tread pattern is asymmetrical with respect to the tire equator Ln, but is not limited to this.

[0015] In this embodiment, the tire 1 comprises a pair of shoulder main grooves 23, 24 formed on the outermost part of the tire axial direction D1, and a pair of center main grooves 21, 22 formed between the pair of shoulder main grooves 23, 24. Of the pair of center main grooves 21, 22, the main groove located on the first axial direction D11 side is called the first center main groove 21, and the main groove located on the second axial direction D12 side is called the second center main groove 22. Of the pair of shoulder main grooves 23, 24, the main groove located on the first axial direction D11 side is called the first shoulder main groove 23, and the main groove located on the second axial direction D12 side is called the second shoulder main groove 24.

[0016] A tire 1 includes a plurality of land portions 3 partitioned by a plurality of main grooves 2. In the present embodiment, the tire 1 includes a center land portion 31 partitioned by a pair of center main grooves 21, 22 that sandwich the tire equatorial line Ln, a first intermediate land portion 32 partitioned by the first center main groove 21 and the first shoulder main groove 23, a second intermediate land portion 33 partitioned by the second center main groove 22 and the second shoulder main groove 24, a first shoulder land portion 34 partitioned by the first shoulder main groove 23, and a second shoulder land portion 35 partitioned by the second shoulder main groove 24.

[0017] In the present embodiment, the center of the center land portion 31 in the width direction is offset from the tire equatorial plane S1 in the first axial direction D11, the width of the first intermediate land portion 32 is larger than the width of the second intermediate land portion 33, and the width of the first shoulder land portion 34 is larger than the width of the second shoulder land portion 35. The groove width of the main grooves 2 (the first center main groove 21 and the first shoulder main groove 23) located on the first axial direction D11 side of the tire equatorial plane S1 is smaller than the groove width of the main grooves 2 (the second center main groove 22 and the second shoulder main groove 24) located on the second axial direction D12 side of the tire equatorial plane S1. Thereby, the rigidity of the land portions 3 on the first axial direction D11 side (the outer side when mounted on a vehicle) of the tire 1 can be improved, and the steering stability performance during vehicle turning can be improved.

[0018] As shown in FIG. 2 and FIG. 3, the tire 1 includes a plurality of lateral grooves 4 extending from the main grooves 2 along the tire axial direction D1. The plurality of lateral grooves 4 are formed at predetermined intervals in the tire circumferential direction D3. The groove width of the lateral grooves 4 (excluding stepped portions 411, 431, narrow width portions 421, 452 and wide width portions 441 described later) is, for example, 2 mm to 5 mm. The groove depth of the lateral grooves 4 (excluding stepped portions 411, 431 and shallow groove portions 451 described later) is, for example, 4 mm to 8 mm. The groove depth of the lateral grooves 4 is smaller than the groove depth of the main grooves 2, but is not limited thereto.

[0019] In the present embodiment, the tire 1 includes a plurality of first mediate lateral grooves 41 formed in a first mediate land 32, a plurality of second mediate lateral grooves 42 formed in a second mediate land 33, a plurality of first shoulder lateral grooves 43 and second shoulder lateral grooves 44 formed in a first shoulder land 34, and a plurality of third shoulder lateral grooves 45 formed in a second shoulder land 35. No lateral groove 4 is provided in the center land 31. The center land 31 is a rib (also referred to as center rib 31) that continuously extends along the tire circumferential direction D3.

[0020] One end of the first mediate lateral groove 41 terminates within the first mediate land 32, and the other end opens into the main groove 2 (the first center main groove 21 or the first shoulder main groove 23). The first mediate land 32 is not divided by the first mediate lateral grooves 41. That is, the first mediate land 32 is a rib (also referred to as mediate rib 32) that continuously extends along the tire circumferential direction D3. The first mediate lateral groove 41 has a width-increasing shape toward the main groove 2.

[0021] The first mediate lateral grooves 41 are formed on both side faces in the width direction of the first mediate land 32 so as to form a pair. The respective inclination angles of the pair of first mediate lateral grooves 41, 41 with respect to the tire axial direction D1 are substantially the same. The pair of first mediate lateral grooves 41, 41 are point-symmetrical with respect to any point on the center line in the width direction of the first mediate land 32 (for example, the center point of a widened portion 321a described later).

[0022] As shown in FIGS. 2 to 5, the first mediate lateral groove 41 is provided with a step 411 that protrudes from the groove wall surface of the first mediate lateral groove 41 toward the inside of the groove. Thereby, while ensuring the drainage performance of the first mediate lateral groove 41, a decrease in rigidity of the land 3 caused by providing the first mediate lateral groove 41 can be suppressed.

[0023] The groove width of the first mediate lateral groove 41, which is provided with a step 411, is, for example, 0.8 mm to 1.5 mm. The depth H3 of the step 411 is preferably the same as the depth H2 (see Figure 7) of the step 6 formed on the groove wall surface of the main groove 2, which will be described later. The first shoulder lateral groove 43 is also provided with a similar step 431.

[0024] As shown in Figures 2 and 3, the second mediate lateral groove 42 has one end opening into the second center main groove 22 and the other end opening into the second shoulder main groove 24. The second mediate land 33 is divided into multiple mediate blocks 33a by the second mediate lateral groove 42. The second mediate land 33 is a row of mediate blocks 33a arranged in the tire circumferential direction D3.

[0025] The second mediate lateral groove 42 is provided with a narrow section 421 that has a smaller groove width than the rest of the second mediate lateral groove 42. The groove width of the narrow section 421 is, for example, 0.8 mm to 1.5 mm. By providing the narrow section 421, the pumping noise generated from the second mediate lateral groove 42 when the tire makes contact with the ground can be reduced.

[0026] The first shoulder lateral groove 43 terminates at one end within the first shoulder rib 34 and opens at the other end into the first shoulder main groove 23. The second shoulder lateral groove 44 opens at one end outward in the tire axial direction D1 and terminates at the other end within the first shoulder rib 34. The first shoulder rib 34 is not separated by the first shoulder lateral groove 43 and the second shoulder lateral groove 44. That is, the first shoulder rib 34 is a rib (also called a shoulder rib 34) that extends continuously along the tire circumferential direction D3.

[0027] The inclination angle of the first shoulder groove 43 with respect to the tire axis direction D1 is substantially the same as the inclination angle of the first mediate groove 41 with respect to the tire axis direction D1. The inclination angle of the first shoulder groove 43 with respect to the tire axis direction D1 is greater than the inclination angle of the second shoulder groove 44 with respect to the tire axis direction D1. The first shoulder groove 43 is formed substantially collinearly with the adjacent first mediate groove 41.

[0028] The second shoulder lateral groove 44 has a wide section 441 that extends towards the shoulder longitudinal narrow groove 342, which will be described later. The wide section 441 is formed at the connection point with the shoulder longitudinal narrow groove 342. The wide section 441 is a part of the second shoulder lateral groove 44 that has a wider groove width than other parts of the second shoulder lateral groove 44.

[0029] The third shoulder lateral groove 45 opens at one end into the second shoulder main groove 24 and at the other end outward in the tire axial direction D1. The second shoulder ridge 35 is divided into multiple shoulder blocks 35a by the third shoulder lateral groove 45. The second shoulder ridge 35 is a row of blocks in which the shoulder blocks 35a are arranged in the tire circumferential direction D3. By making the ridge 3 on the inner side (second axial direction D12 side) when mounted on the vehicle a row of blocks, and the ridge 3 on the outer side (first axial direction D11 side) when mounted on the vehicle a rib, traction performance, braking performance, and handling stability during cornering are improved.

[0030] The third shoulder lateral groove 45 comprises a shallow groove section 451 with a shallower groove depth than the rest of the third shoulder lateral groove 45, and a narrow groove section 452 with a narrower groove width than the rest of the third shoulder lateral groove 45. The shallow groove section 451 is formed at the connection point with the second shoulder main groove 24. The groove wall surface of the shallow groove section 451 on the second circumferential direction D32 side is inclined such that the groove width narrows towards the groove bottom. The narrow groove section 452 is formed adjacent to the outside of the shallow groove section 451 in the tire axial direction D1.

[0031] The groove depth of the shallow groove section 451 is, for example, 1 mm to 3 mm. The groove width of the narrow section 452 is, for example, 0.8 mm to 1.5 mm. By providing the shallow groove section 451 and the narrow section 452, the pumping noise generated from the third shoulder lateral groove 45 when the tire makes contact with the ground can be reduced.

[0032] As shown in Figures 2-4, 6, and 7, the tire 1 is provided with an inclined portion 5 that extends from the upper surface of the base 3 (outer surface of the tread 13) toward the side surface of the base 3 (groove wall surface of the main groove 2) toward the adjacent main groove 2. By providing the inclined portion 5, the groove capacity of the main groove 2 can be increased, and drainage performance can be improved. In addition, by providing the inclined portion 5, the edge of the base 3 can be made obtuse, increasing the rigidity of the base 3 and improving handling stability.

[0033] As shown in Figure 4, the inclined portion 5 comprises a base portion 51 extending along the adjacent main groove 2 and a curved portion 52 that curves from the base portion 51 toward the inside of the land surface 3 on which the inclined portion 5 is provided (towards the center in the width direction of the land surface 3). By providing the curved portion 52, the groove capacity of the main groove 2 can be increased, thereby enhancing the effect of improving the drainage performance of the tire 1. The curved portion 52 curves away from the adjacent main groove 2 as it moves away from the base portion 51.

[0034] From the viewpoint of securing the groove capacity of the main groove 2, it is preferable that the curved portion 52 bends inward from the base portion 51 towards the base 3. In this embodiment, the curved portion 52 is bent at the bending point P1. The curved portion 52 may have a curved shape having multiple bending points, for example, or it may have a curved shape that is bent in an arc shape.

[0035] In this embodiment, the bending angle θ1 of the curved portion 52 with respect to the tire circumferential direction D3 is preferably 1 to 30 degrees. By setting the bending angle θ1 to 1 degree or more, the effect of improving the drainage performance of the main groove 2 can be ensured. By setting the bending angle θ1 to 30 degrees or less, the decrease in rigidity of the base 3 can be suppressed. A bending angle θ1 of 3 degrees or more is more preferable. A bending angle θ1 of 10 degrees or less is even more preferable.

[0036] From the viewpoint of improving drainage performance, it is preferable that the curved portion 52 is curved in the same direction as the inclination direction of the lateral groove 4 with respect to the tire circumferential direction D3. In this embodiment, the lateral groove 4 (first mediate lateral groove 41) is curved in the first axial direction D11 toward the first circumferential direction D31, and the curved portion 52 is also curved in the same direction. However, the curved portion 52 may be curved in a direction different from the inclination direction of the lateral groove 4 with respect to the tire circumferential direction D3.

[0037] The length L2 of the curved portion 52 in the tire circumferential direction D3 is greater than 30% and less than or equal to 70% of the length L1 of the inclined portion 5 in the tire circumferential direction D3. Preferably, the length L2 of the curved portion 52 is 40% or more of the length L1 of the inclined portion 5, and more preferably 45% or more. Preferably, the length L2 of the curved portion 52 is 60% or less of the length L1 of the inclined portion 5, and more preferably 55% or less. The length L1 of the inclined portion 5 is the length of the tire circumferential direction D3 at the inner end of the inclined portion 5 in the tire radial direction D2. The length L2 of the curved portion 52 is the length of the tire circumferential direction D3 at the inner end of the curved portion 52 in the tire radial direction D2.

[0038] From the viewpoint of ensuring the rigidity of the base 3, the innermost dimension W1 of the curved portion 52 is preferably 30% or less of the width of the base 3 on which the curved portion 52 (inclined portion 5) is provided. The innermost dimension W1 is the maximum value of the tire axial direction D1 from the groove wall surface of the main groove 2 adjacent to the curved portion 52 to the curved portion 52. In this embodiment, the innermost dimension W1 is smaller than the length of the tire axial direction D1 of the lateral groove 4.

[0039] As shown in Figure 6, when the depth H1 of the inclined portion 5 is set to a predetermined dimension, the inclination angle θ2 of the inclined portion 5 with respect to the tire radial direction D2 is preferably 30 to 60 degrees. By setting the inclination angle θ2 to 30 degrees or more, the groove capacity of the main groove 2 can be increased, and the effect of improving drainage performance can be enhanced. By setting the inclination angle θ2 to 60 degrees or less, the reduction in the surface area of ​​the land 3 due to the formation of the inclined portion 5 can be suppressed, and wear resistance and grip performance can be ensured. The inclination angle θ2 is more preferably 40 to 50 degrees. In this embodiment, the inclination angle θ2 is constant (including a difference of 10%). That is, the inclination angle of the base portion 51 is substantially the same as the inclination angle of the curved portion 52 (see Figure 7). However, the inclination angle of the base portion 51 may be different from the inclination angle of the curved portion 52.

[0040] The depth H1 of the inclined section 5 is preferably 10% to 70% of the groove depth of the main groove 2. By setting the depth H1 to 10% or more of the groove depth of the main groove 2, the groove capacity of the main groove 2 can be increased, thereby enhancing the effect of improving drainage performance. By setting the depth H1 to 70% or less of the groove depth of the main groove 2, the reduction in the surface area of ​​the land 3 due to the formation of the inclined section 5 can be suppressed, thereby suppressing the decrease in the rigidity of the land 3. In this embodiment, the depth H1 of the inclined section 5 is constant (including a difference of 10%). That is, the depth of the base 51 is substantially the same as the depth of the curved section 52 (see Figure 7).

[0041] The width W2 of the inclined section 5 is preferably 20% to 50% of the groove width W3 of the main groove 2 (see Figure 3). By setting the width W2 to 20% or more of the groove width W3, the groove capacity of the main groove 2 can be effectively increased, ensuring improved drainage performance. By setting the width W2 to 50% or less of the groove width W3, the surface area of ​​the land 3 can be secured, ensuring wear resistance. The groove width W3 of the main groove 2 is the groove width of the main groove at a position adjacent to the inclined section 5. In this embodiment, the width W2 of the inclined section 5 is constant (including a difference of 10%). That is, as shown in Figure 4, the width W21 of the base 51 is substantially the same as the width W22 of the curved section 52. The width W2 of the inclined section 5 is more preferably 30% or more of the groove width W3 of the main groove 2, and even more preferably 40% or more of the groove width W3 of the main groove 2.

[0042] As shown in Figure 3, it is preferable that the inclined portion 5 extends from the lateral groove 4 to the lateral groove 4 adjacent to it in the tire circumferential direction D3. This improves drainage from the main groove 2 to the lateral groove 4, and enhances the drainage performance improvement effect of providing the inclined portion 5. The inclined portion 5 may be formed on land 3 where there are no lateral grooves 4, and may not be connected to the lateral grooves 4.

[0043] In this embodiment, the inclined portion 5 is formed on the side surface of the base 3 located on the first axial direction D11 side (outer side when mounted on a vehicle) of the tire equator Ln. In this embodiment, the inclined portion 5 is formed only on the side surface of the base 3 located on the first axial direction D11 side of the tire equator Ln. Specifically, the inclined portion 5 is formed on both sides of the first mediate base 32 and on the inner side of the first shoulder base 34 in the tire axial direction D1. The inclined portion 5 is not formed on the base 3 located on the second axial direction D12 side (inner side when mounted on a vehicle) of the tire equator Ln, and this structure is advantageous in improving the degree of design freedom.

[0044] The inclined portion 5a provided on the side of the first mediate land 32 on the second axial direction D12 side is point-symmetric with respect to any point on the center line in the width direction of the first mediate land 32 (for example, the center point of the widening portion 321a described later) with respect to the inclined portion 5b provided on the side of the first mediate land 32 on the first axial direction D11 side. The curved portion 52a of the inclined portion 5a is formed at a position that overlaps with the curved portion 52b of the inclined portion 5b when viewed in the tire axial direction D1.

[0045] The inclined portion 5c provided on the first shoulder 34 is substantially the same shape as the inclined portion 5a. That is, the inclined portion 5c is point-symmetric with respect to any point on the center line in the width direction of the first shoulder main groove 23 and the inclined portion 5b. The curved portion 52c of the inclined portion 5c is formed in a position that overlaps with the curved portions 52a and 52b when viewed in the tire axial direction D1.

[0046] From the viewpoint of improving the straight-line performance of the tire 1, it is preferable that the inclined portion 5 is not formed on the side surface of the center base 31. The center base 31 is located closest to the tire equator Ln among the multiple bases 3. In this embodiment, the center base 31 is located on the tire equator Ln. Note that the inclined portion 5 is not limited to the above.

[0047] As shown in Figures 2 to 4 and Figure 7, the tire 1 is provided with a step 6 extending from the groove wall surface of the main groove 2 toward the inside of the ground 3. In this embodiment, the step 6 is formed from the bend point P1 to the end of the bend 52 in the tire circumferential direction D3. The step 6 extends along the main groove 2. The step 6 extends substantially parallel to the upper surface of the ground 3. The step 6 is wider toward the end of the bend 52 in the tire circumferential direction D3. In view in the tire radial direction D2, the step 6 is connected to the step 411 (or step 431) to form a substantially V shape.

[0048] As shown in Figure 7, it is preferable that the curved section 52 is connected to the step 6. The depth H2 of the step 6 is preferably 10% to 70% of the groove depth of the main groove 2. By setting the depth H2 to 10% or more of the groove depth of the main groove 2, the groove capacity of the main groove 2 can be increased, and the drainage performance can be improved. By setting the depth H2 to 70% or less of the groove depth of the main groove 2, a decrease in the rigidity of the land 3 can be suppressed. In this embodiment, the depth H2 of the step 6 is constant (including a difference of 10%).

[0049] As shown in Figures 3 and 4, it is preferable that the step 6 is connected to a step 411 or step 431 provided in the horizontal groove 4. It is preferable that the step 6 is substantially flush with the step 411 or step 431. That is, it is preferable that the depth H2 of the step 6 shown in Figure 7 is substantially the same as the depth H3 of the step 411 or the depth of the step 431 shown in Figure 5. However, the step 6 is not limited to the above.

[0050] As shown in Figures 2 and 3, the center base 31 is provided with a center transverse groove 311 extending along the tire axial direction D1. One end of the center transverse groove 311 opens into the first center main groove 21, and the other end terminates within the center base 31. The other end of the center transverse groove 311 is formed at a position beyond the tire equator Ln.

[0051] The inclination angle of the center lateral groove 311 with respect to the tire axial direction D1 is substantially the same as the inclination angle of the first mediate lateral groove 41 with respect to the tire axial direction D1. The center lateral groove 311 is formed substantially collinearly with the adjacent first mediate lateral groove 41.

[0052] The groove width of the center lateral narrow groove 311 is smaller than the groove width of the lateral groove 4. The groove width of the center lateral narrow groove 311 is, for example, 0.8 mm to 1.5 mm. The groove depth of the center lateral narrow groove 311 is, for example, 4 mm to 8 mm. The same applies to the groove widths and groove depths of the lateral narrow grooves 333, 334, 343, and 351, excluding the wide section 343a described later.

[0053] The center lateral groove 311 is provided with an inclined portion 311a that slopes from the groove wall surface of the center lateral groove 311 toward the upper surface of the center base 31. By providing the inclined portion 311a, the rigidity of the center base 31 can be increased and uneven wear of the center base 31 can be suppressed. The inclined portion 311a extends from the first center main groove 21 to the vicinity of the tire equator line Ln.

[0054] The first mediate base 32 comprises a mediate longitudinal groove 321 formed in the center of the width direction of the first mediate base 32, and a pair of first mediate shallow grooves 322, 322 formed on both sides of the mediate longitudinal groove 321 in the tire axial direction D1. The mediate longitudinal groove 321 and the first mediate shallow grooves 322 extend continuously in the tire circumferential direction D3.

[0055] The width of each mediate longitudinal narrow groove 321 (excluding the widened portion 321a described later) and the first mediate shallow groove 322 is, for example, 0.8 mm to 1.5 mm. The same applies to the widths of each shallow groove 331, 332, 341 and longitudinal narrow groove 342 described later.

[0056] The groove depth of the mediate vertical groove 321 is, for example, 4 mm to 8 mm. The same applies to the groove depth of the vertical groove 342, which will be described later. By providing the mediate vertical groove 321, the rigidity of the first mediate base 32 can be ensured while cooling the heat that accumulates in the center of the width direction of the first mediate base 32.

[0057] The mediate vertical narrow groove 321 is provided with a plurality of widened sections 321a in which the groove width is expanded. The maximum groove width of the widened sections 321a is, for example, 3 mm to 4 mm. By providing the widened sections 321a, the heat that accumulates in the center in the width direction of the first mediate land 32 can be further cooled. The groove wall surface of the widened sections 321a is formed in an arc shape.

[0058] The groove depth of the first mediate shallow groove 322 is smaller than the groove depth of the mediate longitudinal narrow groove 321. The groove depth of the first mediate shallow groove 322 is, for example, 3 mm or less. The groove depth of the first mediate shallow groove 322 is, for example, 1 mm or more. The same applies to the shallow grooves 331, 332, and 341 described later.

[0059] The first mediate shallow groove 322 is connected to the end of the first mediate lateral groove 41. By providing the first mediate shallow groove 322, the traction performance in the tire axial direction D1 can be improved.

[0060] The second mediate groove 33 comprises a second mediate shallow groove 331 and a third mediate shallow groove 332 formed outside the tire axial direction D1 compared to the second mediate shallow groove 331. The mediate shallow grooves 331 and 332 extend along the tire circumferential direction D3.

[0061] The second mediate groove 33 comprises a plurality of first mediate lateral grooves 333 and second mediate lateral grooves 334 extending along the tire axial direction D1. The first mediate lateral grooves 333 have one end opening into the second center main groove 22 and the other end opening into the second mediate shallow groove 331. The second mediate lateral grooves 334 have one end opening into the third mediate shallow groove 332 and the other end opening into the second shoulder main groove 24.

[0062] The inclination angles of the mediate lateral grooves 333 and 334 with respect to the tire axial direction D1 are substantially the same as the inclination angles of the second mediate lateral groove 42 with respect to the tire axial direction D1. One first mediate lateral groove 333 is formed for each mediate block 33a, and two second mediate lateral grooves 334 are formed for each mediate block 33a.

[0063] The first shoulder groove 34 includes a shallow shoulder groove 341 connected to the end of the first shoulder lateral groove 43, a narrow shoulder longitudinal groove 342 connected to the end of the second shoulder lateral groove 44, and a first shoulder lateral groove 343 (see Figure 3) extending outward from the shoulder longitudinal groove 342 in the tire axial direction D1.

[0064] The shoulder shallow grooves 341 and shoulder longitudinal grooves 342 extend continuously in the tire circumferential direction D3. The shoulder shallow grooves 341 are formed inward in the tire axial direction D1 compared to the shoulder longitudinal grooves 342. By providing the shoulder shallow grooves 341, traction performance in the tire axial direction D1 can be improved. By providing the shoulder longitudinal grooves 342, the contact performance of the tire 1 can be improved while ensuring the rigidity of the first shoulder 34.

[0065] The inclination angle of the first shoulder lateral groove 343 with respect to the tire axial direction D1 is substantially the same as the inclination angle of the first shoulder lateral groove 43 with respect to the tire axial direction D1. The first shoulder lateral groove 343 has a wide section 343a that extends towards the shoulder longitudinal groove 342. The wide section 343a is formed at the connection point with the shoulder longitudinal groove 342. The wide section 343a is a portion of the first shoulder lateral groove 343 that has a wider groove width than the rest of the groove. The groove depth of the wide section 343a is, for example, 1 mm to 3 mm.

[0066] The first shoulder ridge 34 is provided with a plurality of steps 344 extending inward in the tire axial direction D1 from the groove wall surface of the shoulder longitudinal groove 342. The steps 344 extend along the shoulder longitudinal groove 342. The width of the steps 344 in the tire axial direction D1 is substantially the same as the groove width of the shoulder longitudinal groove 342. The depth of the steps 344 is, for example, 1 mm to 3 mm. The end face of the steps 344 in the first circumferential direction D31 is substantially flush with the groove wall surface in the first circumferential direction D31 of the second shoulder transverse groove 44 or the first shoulder transverse groove 343.

[0067] The second shoulder block 35 is provided with a plurality of second shoulder lateral grooves 351 extending outward from the second shoulder main groove 24 in the tire axial direction D1. The inclination angle of the second shoulder lateral grooves 351 with respect to the tire axial direction D1 is substantially the same as the inclination angle of the third shoulder lateral groove 45 with respect to the tire axial direction D1. Two second shoulder lateral grooves 351 are formed for each shoulder block 35a.

[0068] [1] As described above, the pneumatic tire 1 according to this embodiment includes a plurality of main grooves 2 extending in the tire circumferential direction D3 provided in the tread 13, a plurality of land areas 3 partitioned by the plurality of main grooves 2, and an inclined portion 5 extending from the upper surface of the land area 3 toward the side toward the adjacent main groove 2, wherein the inclined portion 5 includes a base portion 51 extending along the adjacent main groove 2 and a curved portion 52 bending inward toward the land area 3 from the base portion 51, and the length L2 of the curved portion 52 in the tire circumferential direction D3 is greater than 30% and less than or equal to 70% of the length L1 of the inclined portion 5 in the tire circumferential direction D3.

[0069] With this configuration, by providing the curved section 52, the groove capacity of the main groove 2 can be increased, thereby enhancing the drainage performance of the tire 1. By making the length L2 of the curved section 52 exceed 30% of the length L1 of the inclined section 5, the drainage performance can be enhanced. By making the length L2 of the curved section 52 70% or less of the length L1 of the inclined section 5, the reduction in rigidity of the base 3 can be suppressed. This makes it possible to enhance the drainage performance effect by providing the inclined section 5 while ensuring the rigidity of the base 3.

[0070] [2] Furthermore, in the pneumatic tire 1 described in [1] above, it is preferable that the width W2 of the inclined portion 5 is 20% or more of the groove width W3 of the main groove 2. With such a configuration, the groove capacity of the main groove 2 can be increased, and the effect of improving drainage performance by providing the inclined portion 5 can be enhanced.

[0071] [3] Furthermore, in the pneumatic tire 1 according to [1] or [2] above, it is preferable that a step 6 is formed from the groove wall surface of the main groove 2 toward the inside of the base 3, and the curved portion 52 is connected to the step 6. With such a configuration, by providing the step 6, the reduction in rigidity of the base 3 caused by providing the curved portion 52 can be suppressed.

[0072] [4] Furthermore, in a pneumatic tire 1 relating to any one of the above [1] to [3], it is preferable that the tire is provided with a plurality of lateral grooves 4 extending from the main groove 2 along the tire axis direction D1, and that the inclined portion 5 extends from the lateral groove 4 to the adjacent lateral groove 4. With such a configuration, the drainage from the main groove 2 to the lateral grooves 4 can be improved, and the effect of improving drainage performance by providing the inclined portion 5 can be further enhanced.

[0073] [5] Furthermore, in a pneumatic tire 1 relating to any one of the above [1] to [4], it is preferable that the curved portion 52 is bent inward from the base portion 51 toward the land 3. With such a configuration, the groove capacity of the main groove 2 can be increased compared to when the curved portion 52 is formed in a curved shape, and the effect of improving drainage performance by providing the inclined portion 5 can be enhanced.

[0074] [6] Furthermore, it is preferable that the pneumatic tire 1 relating to any one of the above [1] to [5] has a specified mounting direction relative to the vehicle, and that the inclined portion 5 is formed on the side surface of the ground 3 located outside the tire equatorial plane S1 when mounted on the vehicle.

[0075] With this configuration, by providing an inclined portion 5 on the side surface of the tire 1 located on the outer side when the tire 1 is mounted on a vehicle, the reduction in the drainage performance of the tire 1 due to the narrowing of the groove width of the main groove 2 can be suppressed. The reason why the groove width of the main groove 2 narrows in the outer region of the tire when it is mounted on a vehicle is that the contact pressure on the outer side of the tire tends to increase when the vehicle is turning, and from the viewpoint of ensuring handling stability, it is useful to widen the outer surface of the tire 3 when it is mounted on a vehicle to increase its rigidity.

[0076] It should be noted that the tire 1 is not limited to the configuration of the embodiment described above, nor is it limited to the effects and benefits described above. Furthermore, the tire 1 can be modified in various ways without departing from the spirit of the present invention. For example, one or more of the configurations and methods described below may be arbitrarily selected and adopted in the configurations and methods of the embodiment described above.

[0077] (A) In this embodiment, the inclined portion 5 is configured to have one curved portion 52 on one side in the tire circumferential direction D3. However, the inclined portion 5 is not limited to this configuration. For example, as shown in Figure 8, the inclined portion 5 may be configured to have a first curved portion 521 formed on the first circumferential direction D31 side of the base portion 51, and a second curved portion 522 formed on the second circumferential direction D32 side of the base portion 51.

[0078] In this configuration, the first curved section 521 is bent at the bend point P2, and the second curved section 522 is bent at the bend point P3. The length of the curved section 52 in the tire circumferential direction is the sum of the length of the first curved section 521 in the tire circumferential direction D3 and the length of the second curved section 522 in the tire circumferential direction D3.

[0079] (B) In this embodiment, the tire 1 is configured to have a step 6, and the curved portion 52 is connected to the step 6. However, the tire 1 and the curved portion 52 are not limited to this configuration. For example, the tire 1 may be configured not to have a step 6, as shown in Figures 9 and 10. In such a configuration, the curved portion 52 is connected to the groove wall surface of the main groove 2. The width and depth of the base portion 51 are different from the width and depth of the curved portion 52. [Explanation of Symbols]

[0080] 1...Tire, 11...Bead section, 12...Sidewall, 13...Tread, 14...Carcass ply, 15...Inner liner, 2...Main groove, 21...First center main groove, 22...Second center main groove, 23...First shoulder main groove, 24...Second shoulder main groove, 3...Surface, 31...Center surface, 311...Center lateral narrow groove, 311a...Inclined section, 32...First mediate surface, 321...Mediate longitudinal narrow groove, 321a...Wide section, 322...First mediate shallow groove, 33...Second mediate surface, 33a...Mediate block, 331...Second mediate shallow groove, 332...Third mediate shallow groove, 333...First mediate lateral narrow groove, 334...Second mediate transverse narrow groove, 34...First shoulder base, 341...Shoulder shallow groove, 342...Shoulder longitudinal narrow groove, 343...First shoulder transverse narrow groove, 343a...Wide section, 344...Step, 35...Second shoulder base, 35a...Shoulder block, 351...Second shoulder transverse narrow groove, 4...Transverse groove, 41...First mediate transverse groove, 411...Step, 42...Second mediate transverse groove, 421...Narrow section, 43...First shoulder transverse groove, 431...Step, 44...Second shoulder transverse groove, 441...Wide section, 45...Third shoulder transverse groove, 451...Shallow groove section, 452...Narrow section, 5...Inclined section, 51...Base section, 52...Bend section, 6...Step, P1...Bend point

Claims

1. Multiple main grooves extending in the circumferential direction of the tire are provided in the tread, Multiple landmasses demarcated by the aforementioned multiple main trenches, An inclined portion extending from the upper surface of the land toward the adjacent main groove, The system includes a lateral groove extending from the main groove along the tire axis, The inclined portion comprises a base portion extending along the adjacent main groove and a curved portion bending inward from the base portion toward the land, The length of the curved portion in the tire circumferential direction is greater than 30% and less than or equal to 70% of the length of the inclined portion in the tire circumferential direction. A step in the horizontal groove is formed that protrudes from the groove wall surface toward the inside of the groove. The curved section is connected to the lateral groove step, and is a pneumatic tire.

2. The pneumatic tire according to claim 1, wherein the curved portion extends in a straight line.

3. The pneumatic tire according to claim 1, wherein the width of the inclined portion is 20% or more of the groove width of the main groove.

4. A step is formed from the groove wall surface of the main groove toward the inner side of the land, The pneumatic tire according to claim 1, wherein the curved portion is connected to the step.

5. The tire is provided with a plurality of transverse grooves extending from the main groove along the tire axis, The pneumatic tire according to claim 1, wherein the inclined portion extends from one lateral groove to an adjacent lateral groove.

6. The pneumatic tire according to claim 1, wherein the curved portion is bent inward from the base portion toward the land portion.

7. The mounting direction on the vehicle is specified. The pneumatic tire according to any one of claims 1 to 6, wherein the inclined portion is formed on the side surface of the land that is located outside the tire's equatorial plane when mounted on a vehicle.

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