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US-12617240-B2 - Tire

US12617240B2US 12617240 B2US12617240 B2US 12617240B2US-12617240-B2

Abstract

In a tire, a middle land portion includes a first middle narrow groove having a linear shape or an arc shape and extending through the middle land portion and a second middle narrow groove having a Z-shape and extending through the middle land portion. A center land portion includes a first center narrow groove having one end at an edge portion of the center land portion, connected to a center main groove, and having an other end inside the center land portion and a second center narrow groove extending in a tire circumferential direction and having both ends inside the center land portion. The first center narrow groove is inclined in one direction of the tire circumferential direction from the one end toward the other end. The first and second center narrow grooves are arranged in a V-shape whose top portion is directed to the one direction.

Inventors

  • Hiroto Kikuchi

Assignees

  • THE YOKOHAMA RUBBER CO., LTD.

Dates

Publication Date
20260505
Application Date
20221201
Priority Date
20220331

Claims (19)

  1. 1 . A tire, comprising: a plurality of shoulder main grooves and two or more center main grooves; and a plurality of shoulder land portions, a pair of middle land portions, and one or more center land portions defined and formed by the shoulder main grooves and the center main grooves; at least one middle land portion of the middle land portions comprising: a first middle narrow groove having a linear shape or an arc shape and extending through the middle land portion; and a second middle narrow groove having a Z-shape and extending through the middle land portion, the first middle narrow groove and the second middle narrow groove being alternately arranged in a tire circumferential direction, a center land portion of the center land portions comprising: a first center narrow groove having one end at an edge portion of the center land portion, connected to a center main groove of the center main grooves, and having an other end inside the center land portion; and a second center narrow groove extending in the tire circumferential direction and having both ends inside the center land portion, the first center narrow groove being inclined in one direction of the tire circumferential direction from the one end toward the other end, the first center narrow groove and the second center narrow groove being arranged in a V-shape whose top portion is directed to the one direction of the tire circumferential direction, and the first middle narrow groove and the first center narrow groove being inclined in an identical direction with respect to a tire width direction.
  2. 2 . The tire according to claim 1 , wherein the second middle narrow groove is made up of a pair of first groove portions extending in a tire width direction and a second groove portion extending in the tire circumferential direction, one of the first groove portions opening to a shoulder main groove of the shoulder main grooves and an other one of the first groove portions opening to the center main groove, the second groove portion connecting the pair of first groove portions, and an extension length Ls 22 of the second groove portion in the tire circumferential direction with respect to a ground contact width Wb 2 of the middle land portion is in a range 0.10≤Ls 22 /Wb 2 ≤0.50.
  3. 3 . The tire according to claim 1 , wherein the second middle narrow groove is made up of a pair of first groove portions extending in a tire width direction and a second groove portion extending in the tire circumferential direction, one of the first groove portions opening to a shoulder main groove of the shoulder main grooves and an other one of the first groove portions opening to the center main groove, the second groove portion connecting the pair of first groove portions, and extension lengths Ds 22 a , Ds 22 b of the pair of first groove portions with respect to a ground contact width Wb 2 of the middle land portion are in a range 0.70≤(Ds 22 a +Ds 22 b )/Wb 2 ≤1.30.
  4. 4 . The tire according to claim 1 , wherein the center land portion is a rib having a road contact surface continuous in the tire circumferential direction.
  5. 5 . The tire according to claim 1 , wherein an extension length Ds 31 of the first center narrow groove in a tire width direction with respect to a ground contact width Wb 3 of the center land portion is in a range 0.30≤Ds 31 /Wb 3 ≤0.70.
  6. 6 . The tire according to claim 1 , wherein in the middle land portion and the center land portion adjacent to each other across the center main groove, the pitch number of the first center narrow groove that opens to the center main groove is equal to the pitch number of the first middle narrow groove.
  7. 7 . The tire according to claim 1 , wherein groove widths of the first middle narrow groove and the first center narrow groove are in a range of 1.5 mm or more and 3.0 mm or less.
  8. 8 . The tire according to claim 1 , wherein the first center narrow groove is on an extension line of a groove center line of the first middle narrow groove.
  9. 9 . The tire according to claim 1 , wherein the shoulder land portion is a rib having a road contact surface continuous in the tire circumferential direction.
  10. 10 . The tire according to claim 1 , wherein a ground contact width Wb 2 of the middle land portion with respect to a ground contact width Wb 1 of the shoulder land portion is in a range 0.70≤Wb 2 /Wb 1 ≤0.85.
  11. 11 . The tire according to claim 1 , comprising an indicator portion indicating a tire rotation direction, wherein the first center narrow groove is inclined in the tire rotation direction from the one end toward the other end.
  12. 12 . The tire according to claim 2 , wherein the second middle narrow groove is made up of a pair of first groove portions extending in a tire width direction and a second groove portion extending in the tire circumferential direction, one of the first groove portions opening to a shoulder main groove of the shoulder main grooves and an other one of the first groove portions opening to the center main groove, the second groove portion connecting the pair of first groove portions, and extension lengths Ds 22 a , Ds 22 b of the pair of first groove portions with respect to a ground contact width Wb 2 of the middle land portion are in a range 0.70≤(Ds 22 a +Ds 22 b )/Wb 2 ≤1.30.
  13. 13 . The tire according to claim 12 , wherein the center land portion is a rib having a road contact surface continuous in the tire circumferential direction.
  14. 14 . The tire according to claim 13 , wherein an extension length Ds 31 of the first center narrow groove in a tire width direction with respect to a ground contact width Wb 3 of the center land portion is in a range 0.30≤Ds 31 /Wb 3 ≤0.70.
  15. 15 . The tire according to claim 14 , wherein in the middle land portion and the center land portion adjacent to each other across the center main groove, the pitch number of the first center narrow groove that opens to the center main groove is equal to the pitch number of the first middle narrow groove.
  16. 16 . The tire according to claim 15 , wherein groove widths of the first middle narrow groove and the first center narrow groove are in a range of 1.5 mm or more and 3.0 mm or less.
  17. 17 . The tire according to claim 16 , wherein the first center narrow groove is on an extension line of a groove center line of the first middle narrow groove.
  18. 18 . The tire according to claim 17 , further comprising an indicator portion indicating a tire rotation direction, wherein the shoulder land portion is a rib having a road contact surface continuous in the tire circumferential direction, a ground contact width Wb 2 of the middle land portion with respect to a ground contact width Wb 1 of the shoulder land portion is in a range 0.70≤Wb 2 /Wb 1 ≤0.85, and the first center narrow groove is inclined in the tire rotation direction from the one end toward the other end.
  19. 19 . A tire, comprising: a plurality of shoulder main grooves and two or more center main grooves; and a plurality of shoulder land portions, a pair of middle land portions, and one or more center land portions defined and formed by the shoulder main grooves and the center main grooves; at least one middle land portion of the middle land portions comprising: a first middle narrow groove having a linear shape or an arc shape and extending through the middle land portion; and a second middle narrow groove having a Z-shape and extending through the middle land portion, the first middle narrow groove and the second middle narrow groove being alternately arranged in a tire circumferential direction, a center land portion of the center land portions comprising: a first center narrow groove having one end at an edge portion of the center land portion, connected to a center main groove of the center main grooves, and having an other end inside the center land portion; and a second center narrow groove extending in the tire circumferential direction and having both ends inside the center land portion, the first center narrow groove being inclined in one direction of the tire circumferential direction from the one end toward the other end, the first center narrow groove and the second center narrow groove being arranged in a V-shape whose top portion is directed to the one direction of the tire circumferential direction, and the first center narrow groove being on an extension line of a groove center line of the first middle narrow groove.

Description

TECHNICAL FIELD The technology relates to a tire and particularly relates to a tire that can provide snow performance and low rolling resistance performance of the tire in a compatible manner. To reduce tire rolling resistance, recent heavy duty tires employ a configuration in which a lateral groove extending through a middle land portion and a center land portion is a narrow groove having a groove width 3.0 mm or less. The technology described in Japan Patent No. 5498466 B is a known tire employing such a configuration. On the other hand, recent all-season tires need to ensure snow performance. SUMMARY The technology provides a tire that can provide snow performance and low rolling resistance performance of the tire in a compatible manner. A tire according to an embodiment of the technology includes: a plurality of shoulder main grooves and two or more center main grooves; and a plurality of shoulder land portions, a pair of middle land portions, and one or more center land portions defined and formed by the shoulder main grooves and the center main grooves. At least one middle land portion of the middle land portions includes: a first middle narrow groove having a linear shape or an arc shape and extending through the middle land portion; and a second middle narrow groove having a Z-shape and extending through the middle land portion. The first middle narrow groove and the second middle narrow groove are alternately arranged in a tire circumferential direction. A center land portion of the center land portions includes: a first center narrow groove having one end at an edge portion of the center land portion, connected to a center main groove of the center main grooves, and having an other end inside the center land portion; and a second center narrow groove extending in the tire circumferential direction and having both ends inside the center land portion. The first center narrow groove is inclined in one direction of the tire circumferential direction from the one end toward the other end, and the first center narrow groove and the second center narrow groove are arranged in a V-shape whose top portion is directed to the one direction of the tire circumferential direction. In the tire according to an embodiment of the present technology, (1) the middle land portion includes the second middle narrow groove having a Z-shape, thus edge components of the middle land portion are increased, and snow performance of the tire is improved as compared with a configuration in which all through narrow grooves have a linear shape or an arc shape. Further, (2) the center land portion includes the first and second center narrow grooves arranged in a V-shape, thus the rigidity of the center land portion is ensured, and tire rolling resistance is reduced as compared with a configuration in which the center land portion includes a through narrow groove. Furthermore, the first and second center narrow grooves arranged in a V-shape ensure edge components in both the tire circumferential direction and the tire width direction, and thus snow acceleration performance and anti-lateral skid performance of the tire are provided in a compatible manner. Therefore, there is an advantage of providing the snow performance and low rolling resistance performance of the tire in a compatible manner. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view in a tire meridian direction illustrating a tire according to an embodiment of the technology. FIG. 2 is a plan view illustrating a tread surface of the tire illustrated in FIG. 1. FIG. 3 is an enlarged view illustrating a middle land portion and a center land portion of the tire illustrated in FIG. 2. FIG. 4 is an enlarged plan view illustrating the center land portion illustrated in FIG. 3. FIG. 5 is a cross-sectional view illustrating the center land portion illustrated in FIG. 3. FIG. 6 is an enlarged plan view illustrating the middle land portion illustrated in FIG. 3. FIG. 7 is a cross-sectional view illustrating the middle land portion illustrated in FIG. 3. FIG. 8 is an enlarged view illustrating a center main groove illustrated in FIG. 3. FIGS. 9A-9B include a table showing results of performance tests of tires according to embodiments of the technology. FIGS. 10A-10B include a table showing results of performance tests of tires according to embodiments of the technology. DETAILED DESCRIPTION Embodiments of the technology will be described in detail below with reference to the drawings. Note that the technology is not limited to the embodiments. Additionally, constituents of the embodiments include constituents that are substitutable and are obviously substitutes while maintaining consistency with the embodiments of the technology. Additionally, a plurality of modified examples described in the embodiments can be combined in a discretionary manner within the scope apparent to one skilled in the art. Tire FIG. 1 is a cross-sectional view in a tire meridian direction illustr