WINTER TIRE TREAD

Abstract

A tread for a tire includes a center rib formed by two circumferential main grooves extending along a tire circumferential direction in a center of a tread width direction. Each circumferential main groove being the same axial distance from a tire equatorial plane of the tread. The center rib has a plurality of first main inclined grooves and a plurality of second main inclined grooves. The first and second main inclined grooves are inclined oppositely with respect to the tire circumferential direction such that the first and second main inclined grooves become distanced from the tire equatorial plane from trailing edges in a tire rotational direction toward leading edges. One zigzag shaped central groove is disposed on one side of the tire equatorial plane and the other zigzag shaped central groove is disposed on an opposite side of the tire equatorial plane.

Claims

1. A tread for a tire comprising: a center rib formed by two circumferential main grooves extending along a tire circumferential direction in a center of a tread width direction, each circumferential main groove being the same axial distance from a tire equatorial plane of the tread; the center rib having a plurality of first main inclined grooves and a plurality of second main inclined grooves, the first and second main inclined grooves being inclined oppositely with respect to the tire circumferential direction such that the main inclined grooves become distanced from the tire equatorial plane from trailing edges in a tire rotational direction toward leading edges, the trailing edges of the first main inclined grooves connecting with one circumferential main groove, while the trailing edges of the second main inclined grooves connect with the other circumferential main groove, the first and second main inclined grooves being arranged such that mutual leading edges thereof are disposed alternately in the tire circumferential direction, extend axially beyond the tire equatorial plane, and define two zigzag shaped central grooves along the tire circumferential direction, one zigzag shaped central groove disposed on one side of the tire equatorial plane and the other zigzag shaped central groove disposed on an opposite side of the tire equatorial plane.

2. The tread as set forth in claim 1 wherein each first main inclined groove intersects with between 3 and 6 second main inclined grooves with leading edges of each first main inclined groove being disposed at a different second main inclined groove.

3. The tread as set forth in claim 1 wherein each second main inclined groove intersects with between 3 and 6 first main inclined grooves with leading edges of each second main inclined groove being disposed at a different first main inclined groove.

4. The tread as set forth in claim 1 wherein each zigzag groove has a groove width in a range from 2.0 mm to 6.0 mm.

5. The tread as set forth in claim 1 wherein the first and second main inclined grooves radially outside of the zigzag grooves have a groove width in a range of 2.0 mm to 10.0 mm and a radial groove depth in a range of 2.0 mm to 10.0 mm.

6. The tread as set forth in claim 1 wherein the first and second main inclined grooves have a curved shape.

7. The tread as set forth in claim 1 wherein the first and second main inclined grooves form opposite angles with respect to the circumferential main grooves, the angles being between 56 and 76 and 56 and 76.

8. The tread as set forth in claim 1 wherein the first and second main inclined grooves form equal and opposite angles with respect to the circumferential main grooves at trailing edges connecting to the circumferential main grooves.

9. The tread as set forth in claim 1 further including a first shoulder rib and a second shoulder disposed adjacent the center rib, the first and second shoulder ribs including inclined transverse grooves extending axially outward from the circumferential main grooves.

10. The tread as set forth in claim 9 wherein the inclined transverse grooves have a groove width from 2.0 mm to 4.0 mm and a radial groove depth from 2.0 mm to 4.0 mm.

11. A tread for a tire comprising: a center rib formed by two circumferential main grooves extending along a tire circumferential direction in a center of a tread width direction, each circumferential main groove being the same axial distance from a tire equatorial plane of the tread; the center rib having a plurality of first main inclined grooves and a plurality of second main inclined grooves, the first and second main inclined grooves being inclined oppositely with respect to the tire circumferential direction such that the main inclined grooves become distanced from the tire equatorial plane from trailing edges in a tire rotational direction toward leading edges, the trailing edges of the first main inclined grooves connecting with one circumferential main groove, while the trailing edges of the second main inclined grooves connect with the other circumferential main groove, the first and second main inclined grooves being arranged such that mutual leading edges thereof are disposed alternately in the tire circumferential direction, extend axially beyond the tire equatorial plane, and define a zigzag shaped central groove extending along the tire circumferential direction, the zigzag shaped central groove being completely disposed on one side of the tire equatorial plane.

12. The tread as set forth in claim 11 wherein each first main inclined groove intersects with 4 second main inclined grooves with leading edges of each first main inclined groove being disposed at a different second main inclined groove.

13. The tread as set forth in claim 11 wherein each second main inclined groove intersects with 5 first main inclined grooves with leading edges of each second main inclined groove being disposed at a different first main inclined groove.

14. The tread as set forth in claim 11 wherein each zigzag groove has a groove width in a range from 2.0 mm to 6.0 mm.

15. The tread as set forth in claim 11 wherein the main inclined grooves radially outside of the zigzag groove have a groove width in a range of 2.0 mm to 10.0 mm and a radial groove depth in a range of 2.0 mm to 10.0 mm.

16. The tread as set forth in claim 11 wherein the first and second main inclined grooves have a linear shape.

17. The tread as set forth in claim 11 wherein the first and second main inclined grooves form opposite angles with respect to the circumferential main grooves, the angles being between 50 and 70 and 50 and 70.

18. The tread as set forth in claim 11 further including a shoulder rib disposed adjacent the center rib, the shoulder rib including inclined transverse grooves extending axially outward.

19. The tread as set forth in claim 18 wherein the inclined transverse grooves have a groove width from 2.0 mm to 4.0 mm and a radial groove depth from 2.0 mm to 4.0 mm.

20. The tread as set forth in claim 19 further including a second shoulder rib disposed adjacent the center rib on an opposite axial side of the center rib from the first shoulder rib, the second shoulder rib including inclined transverse grooves extending axially outward at an angle opposite the inclined transverse grooves of the first shoulder rib.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] The present invention will be more clearly understood by the following description of some examples thereof, with reference to the accompanying drawings, in which:

[0094] FIG. 1 is a schematic perspective view of an example tire in accordance with the present invention.

[0095] FIG. 2 is a schematic plan view of the tire illustrated in FIG. 1.

[0096] FIG. 3 is a schematic enlarged plan view of the tire illustrated in FIG. 1.

[0097] FIG. 4 is a schematic sectional view taken along line 4-4 in FIG. 3.

DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0098] An example of the present invention is described below in detail based on the drawings. However, the present invention is not limited to this example. The constituents of the example include components that may be replaced by those skilled in the art with components substantially equivalent. Furthermore, the multiple modified alternatives described in the example may be combined as desired within the scope apparent to one skilled in the art.

[0099] In the following description, tire radial direction refers to a direction orthogonal to the rotational axis of a tire 1; inner side in the tire radial direction refers to the side facing the rotational axis in the tire radial direction; and outer side in the tire radial direction refers to the side distanced from the rotational axis in the tire radial direction. The tire 1 may be pneumatic or non-pneumatic. Additionally, tire width direction refers to the direction parallel to the rotational axis; inner side in the tire width direction refers to the side facing a tire equatorial plane (tire equator line) CL in the tire width direction; and outer side in the tire width direction refers to the side distanced from the tire equatorial plane CL in the tire width direction. Furthermore, tire circumferential direction refers to a circumferential direction with the rotational axis as a center axis. Tire equatorial plane CL refers to a plane that is orthogonal to the rotational axis of the tire 1 and that passes through a center of a tire width of the tire 1. Tire equator line refers to a line along the circumferential direction of the tire 1 that lies on the tire equatorial plane CL. In this example, tire equator line is given the same reference symbol CL as that used for the tire equatorial plane.

[0100] As illustrated in FIG. 1, an example tire 1 in accordance with the present invention may have a tread 2, or tread portion. The tread portion 2 may be formed from a rubber material exposed on a radially outermost side in the tire radial direction of the tire 1 thereby defining a profile of the tire 1 (FIG. 4). The tread portion 2 may have ground contact edges T set at certain positions on both axially outer sides in the tire width direction and a distance between the ground contact edges T in the tire width direction may be set as the ground contact width, or tread width TW.

[0101] The tread width TW may refer to the maximum width in the tire width direction of a region (e.g., a ground contact region) in which the tread portion 2 of the tire 1 contacts the road surface when the tire 1 is installed and loaded. The ground contact edges T may continue in the tire circumferential direction around the tire 1, as illustrated in FIGS. 1 & 2.

[0102] Two circumferential main grooves 3 may extend along the tire circumferential direction to both sides of the tire equatorial plane CL. Ribs that are parallel to the tire equatorial plane CL may and extend along the tire circumferential direction are formed on the surface 2a of the tread portion 2 by the two circumferential main grooves 3. A center rib 4 may extend circumferentially to both side of the tire equatorial plane CL and first and second shoulder ribs 5, 6 may extend circumferentially on the axially outer sides of the circumferential main grooves 3.

[0103] The circumferential main grooves 3 may be disposed such that an axial distance W1 from the tire equatorial plane CL to the center of the circumferential main grooves 3 is constant. For example, the axial distance W1 may be the tread width TW divided by 2, or 40 percent to 60 percent of the tread width TW. The circumferential main grooves 3 may have an axial groove width in a range of 2 percent to 10 percent of the tread width TW and a radial groove depth in a range of 6.0 mm to 10.0 mm. As shown in FIG. 4, groove walls of the circumferential main grooves 3 may be oriented in a relatively upright, or radial, position.

[0104] In accordance with the present invention, a plurality of first main inclined grooves 15 and a plurality of second main inclined grooves 16 may be in the center rib 4 of the tread 1. The first and second main inclined grooves 15, 16 may be inclined oppositely with respect to the tire circumferential direction such that the main inclined grooves 15, 16 become distanced from the tire equatorial plane CL from trailing edge in the tire rotational direction (downward in FIGS. 1-3) toward leading edge. Trailing edges of the first main inclined grooves 15 may connect with one circumferential main groove 3, while trailing edges of the second main inclined grooves 16 may connect with the other circumferential main groove 3. Furthermore, the first and second main inclined grooves 15, 16 may be arranged such that mutual leading edges thereof are disposed alternately in the tire circumferential direction, extend axially beyond the tire equatorial plane CL, and define two zigzag shaped central grooves 17, 18 along the tire circumferential direction on both axial sides of the tire equatorial plane CL. As shown in FIG. 3, the zigzag grooves 17, 18 may not be equidistant from, or symmetric about, the centerline CL of the tread 100.

[0105] Each first main inclined groove 15 may thereby cross over, or intersect, with 3, 4, 5, or 6 second main inclined grooves 16 with leading edges of each first main inclined groove 15 being disposed at a different second main inclined groove 16. Likewise, each second main inclined groove 16 may thereby cross over, or intersect, with 3, 4, 5, or 6 first main inclined grooves 15 with leading edges of each second main inclined groove 16 being disposed at a different first main inclined groove 15 (FIG. 3).

[0106] The zigzag grooves 17, 18 may be formed with a groove width in a range from 2.0 mm to 6.0 mm. The zigzag grooves 17, 18 may be formed with a radial groove depth in a range from 2.0 mm to 6.0 mm. The first and second main inclined grooves 15, 16 radially outside of the zigzag grooves 17, 18 may be formed with a groove width in a range of 2.0 mm to 10.0 mm and a radial groove depth in a range of 2.0 mm to 10.0 mm. The main inclined grooves 15, 16 may have a curved shape (FIGS. 1-3) or may also have a linear shape (not shown). The first and second main inclined grooves 15, 16 may form equal and opposite angles 19 with respect to the circumferential main grooves 3 (tire circumferential direction) at trailing edges connecting to the circumferential main grooves in a range of 56 to 76 and 56 to 76; or 60 to 70 and 60 to 70.

[0107] The first and second shoulder ribs 5, 6 may include inclined transverse grooves 8 extending generally axially outward from the circumferential main grooves 3. The inclined transverse grooves 8 may have a groove width from 2.0 mm to 4.0 mm, and a radial groove depth from 2.0 mm to 4.0 mm. The inclined transverse grooves 8 may form equal and opposite angles 19 with respect to the circumferential main grooves 3 (tire circumferential direction) at leading edges connecting to the circumferential main grooves in a range of 75 to 90 and 75 to 90; or 80 to 90 and 80 to 90.

[0108] The center rib 4 may also have a multitude of sipes 41 which may be linear, wavy, zigzag, curved, bent, and/or other suitable configuration. The sipes 41 may extend along the same directions as the first and second main inclined grooves 15, 16. The first and second shoulder ribs 5, 6 may have a multitude of sipes 81 which may be linear, wavy, zigzag, curved, bent, and/or other suitable configuration. The sipes 81 may extend along the same directions as the inclined transverse grooves 8.

[0109] The sipes 41, 81 may include configurations in which both ends are terminated (e.g., blind), a configuration in which one end is terminated and the other end communicates with a groove/sipe (e.g., one end blind), and a configuration in which both ends communicate with grooves/sipes.

[0110] In accordance with the present invention, the tread 2 of the example tire 1 may exhibit enhanced water discharge performance and enhanced snow discharge performance such that steering stability on wet road surfaces is increased and steering stability on snow-covered road surfaces is also increased by functioning of the first and second main inclined grooves 15, 16 extending from the center of the tire width direction (at or near the tire equatorial plane CL) toward the outer sides of the tread width TW. Moreover, through the intersections, at multiple locations with multiple grooves, of the first and second main inclined grooves 15, 16, overall stiffness of the tread 2 may be maintained such that steering stability on dry road surfaces may be acceptable or better. As a result, steering stability on snow-covered road surfaces may be improved without causing deterioration in steering stability on dry and wet road surfaces. Additionally, the zigzag shaped central grooves 17, 18 further contribute to this stability.

[0111] While certain representative details and examples have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in the art that various changes and/or modifications may be made therein without departing from the spirit or scope of the present invention as set forth by the following claims.