TREAD FOR A TIRE

Abstract

A tire tread includes a middle rib formed by two circumferential main grooves extending along a tire circumferential direction, a first shoulder rib disposed axially outward from the center rib and one of the circumferential main grooves, and a second shoulder rib disposed axially outward from the center rib and the other of the two circumferential main grooves. The middle rib has a plurality of sipes inclined oppositely with respect to a tire rotational direction such that the sipes extend farther away from a rotational axis of the tire tread as the sipes extend in the tire rotational direction. The middle rib thereby defines a row of circumferentially extending tread elements having chamfers at trailing edges of the tread elements.

Claims

1. A tire tread comprising: a middle rib formed by two circumferential main grooves extending along a tire circumferential direction; a first shoulder rib disposed axially outward from the center rib and one of the circumferential main grooves; and a second shoulder rib disposed axially outward from the center rib and the other of the two circumferential main grooves, the middle rib having a plurality of sipes inclined oppositely with respect to a tire rotational direction such that the sipes extend farther away from a rotational axis of the tire tread as the sipes extend in the tire rotational direction, the middle rib thereby comprising a row of circumferentially extending tread elements having chamfers at trailing edges of the tread elements.

2. The tire tread as set forth in claim 1 wherein the chamfers extend at an angle between 20 degrees and 40 degrees relative to a radial direction of the tire tread.

3. The tire tread as set forth in claim 1 wherein the chamfers extend at an angle between 25 degrees and 35 degrees relative to a radial direction of the tire tread.

4. The tire tread as set forth in claim 1 wherein the chamfers extend at an angle of about 30 degrees relative to a radial direction of the tire tread.

5. The tire tread as set forth in claim 1 wherein the sipes extend at an angle between 10 degrees and 30 degrees relative to a radial direction of the tire tread.

6. The tire tread as set forth in claim 1 wherein the sipes extend at an angle between 17 degrees and 23 degrees relative to a radial direction of the tire tread.

7. The tire tread as set forth in claim 1 wherein the sipes extend at an angle of about 20 degrees relative to a radial direction of the tire tread.

8. The tire tread as set forth in claim 1 wherein the middle rib has an axial width between 15.0 mm and 30.0 mm.

9. The tire tread as set forth in claim 1 wherein the middle rib has an axial width between 17.0 mm and 26.0 mm.

10. The tire tread as set forth in claim 1 wherein the middle rib has an axial width of about 21.5 mm.

11. The tire tread as set forth in claim 1 wherein the sipes have a radial depth between 5.0 mm and 7.0 mm.

12. The tire tread as set forth in claim 1 wherein the sipes have a radial depth between 5.5 mm and 6.5 mm.

13. The tire tread as set forth in claim 1 wherein the sipes have a radial depth of about 6.0 mm.

14. The tire tread as set forth in claim 1 wherein the sipes have radially upper part and a radially lower part, the chamfers comprising an entire wall of one wall of the radially upper part, the radially upper part having a radial depth between 0.75 mm and 1.75 mm.

15. The tire tread as set forth in claim 1 wherein the sipes have radially upper part and a radially lower part, the chamfers comprising an entire wall of one wall of the radially upper part, the radially upper part having a radial depth between 1.00 mm and 1.50 mm.

16. The tire tread as set forth in claim 1 wherein the sipes have radially upper part and a radially lower part, the chamfers comprising an entire wall of one wall of the radially upper part, the radially upper part having a radial depth about 1.25 mm.

17. The tire tread as set forth in claim 1 wherein the sipes have a radially upper part and a radially lower part, the radially lower part having a uniform circumferential width between 0.50 mm and 1.50 mm.

18. The tire tread as set forth in claim 1 wherein the sipes have a radially upper part and a radially lower part, the radially lower part having a uniform circumferential width between 0.75 mm and 1.25 mm.

19. The tire tread as set forth in claim 1 wherein the sipes have a radially upper part and a radially lower part, the radially lower part having a uniform circumferential width of about 1.00 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The accompanying drawings, which are incorporated in, and constitute a part of, this specification, illustrate examples of the present invention and, together with a general description of the present invention given above, and the detailed description given below, serve to explain the present invention.

[0093] FIG. 1 is a schematic orthogonal view of a tire tread in accordance with the present invention;

[0094] FIG. 2 is a schematic perspective view of part of the tire tread of FIG. 1;

[0095] FIG. 3 is a schematic perspective view of another part of the tire tread of FIG. 1;

[0096] FIG. 4 is a schematic side view of the tire tread of FIG. 1 in an ideally loaded condition; and

[0097] FIG. 5 is a schematic side detail of one of the sipes of FIG. 4.

DETAILED DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0098] This description is made for the purpose of illustrating the general principles of the present invention and should not be understood in a limiting sense. The scope of the present invention is best determined by reference to the appended claims. The reference numerals as depicted in the drawings are the same as those referred to in this specification. Any further structural limitations of the example tire and tread may be specified in U.S. Patent No. 9,174,495, herein incorporated by reference in its entirety.

[0099] FIG. 1 shows an example pneumatic or non-pneumatic tire tread 1 having a contact surface 3, such as a road, and a first circumferential shoulder rib 11, a second circumferential intermediate rib 12, a third circumferential center rib 13, a fourth circumferential intermediate rib 14, and a fifth circumferential shoulder rib 15, each separated axially by a circumferential groove 9. The first rib 11 may have axially extending first sipes 111. The second rib 12 may have axially extending second sipes 122. The third rib 13 may have axially extending third sipes 133. The fourth rib 14 may have axially extending fourth sipes 144. The fifth rib 15 may have axially extending fifth sipes 155. The first sipes 111 and the fifth sipes 155 axially outer straight portions 117, 157 axially transitioning to axially inner angled portions 119, 159, respectively. The inner angled portions 119, 159 and the second, third and fourth ribs 122, 133, 144 may have axial thicknesses between 15.0 mm and 30.0 mm, or 17.0 mm and 26.0 mm, or between 21.0 mm and 23.0 mm, or 21.5 mm.

[0100] As shown in FIGS. 3 and 5, the inner angled portions 119, 159 of the first and fifth ribs 11, 15, the second sipes 122, the third sipes 133, and the fourth sipes 144 may extend radially inward (and circumferentially) at a first angle k to a radial depth p from the contact surface 3. Angle k may be between 10 degrees and 30 degrees, or between 17 degrees and 23 degrees, or 20 degrees. The radial depth p may be between 5.0 mm and 7.0 mm, or 5.5 mm and 6.5 mm, or 6.0 mm. Each inner angled portion 119, 159 and each sipe 122, 133, 144 may have a radially upper part 21 and a radially lower part 22. One wall of the radially upper part 21 may extend directly radially inward to a depth of r from the contact surface 3. The depth r may be between 0.75 mm and 1.75 mm, or 1.00 mm and 1.50 mm, or 1.25 mm. At the depth r, both sides of the radially lower part 22 of the inner angled portions 119, 159 and the sipes 122, 133, 144 may extend radially inward at the first angle k. The angled radially lower part 22 may have a circumferential thickness t. The thickness t may be between 0.50 mm and 1.50 mm, or between 0.75 mm and 1.25 mm, or 1.00 mm. The other wall of the radially upper part 21 may extend radially outward from the radially lower part 22 at a second angle s to form a chamfer 23 at the radially outermost leading edge of the inner angled portions 119, 159 and the sipes 122, 133, 144. Said another way, this defines a structure of each tread element 25 of the ribs 11, 12, 13, 14, 15 having the chamfer 23 at the trailing edge (e.g., the final edge of a tread element to contact a road surface, etc.) of the tread elements 25. The second angle s may be between 20 degrees and 40 degrees, or between 25 degrees and 35 degrees, or 30 degrees.

[0101] Conventionally, tread design optimization for braking tends to impact wet and dry braking in opposite directions. A general trend is that lower tread stiffness improves wet braking, but penalizes dry braking. The above described sipes 111, 122, 133, 144, 155 may allow optimization of wet braking without the trade-off in dry braking. FIG. 4 illustrate an example of the sipes 111, 122, 133, 144, 155 of the tire tread 1 operating under wet braking conditions.

[0102] The present invention has been described with reference to the above examples. Modifications and alterations may occur to others upon reading and understanding of this specification. The specification is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof.