STABILIZER STRUCTURE FOR A TREAD OF A TIRE

Abstract

A tread for a tire includes a first circumferential main groove, a second circumferential main groove, a third circumferential main groove, and a fourth circumferential main groove. The fourth main groove has a stabilizing structure for increasing tread stiffness. The stabilizing structure has a circumferentially extending wavy subgroove in a radially innermost bottom of the fourth circumferential main groove.

Claims

1. A tread for a tire comprising: a first circumferential main groove; a second circumferential main groove; a third circumferential main groove; and a fourth circumferential main groove, the fourth main groove having a stabilizing structure for increasing tread stiffness, the stabilizing structure having a circumferentially extending wavy subgroove in a radially innermost bottom of the fourth circumferential main groove.

2. The tread as set forth in claim 1 wherein the subgroove has a curved, cylindrical radially innermost surface for mitigating cracking and increasing axial flexibility of the stabilizing structures.

3. The tread as set forth in claim 2 wherein an axial width of the subgroove shrinks to 0.0 mm under a predetermined operating condition.

4. The tread as set forth in claim 3 wherein the subgroove has a first sidewall and a second sidewall interconnected by the curved, cylindrical radially innermost surface of the subgroove.

5. The tread as set forth in claim 4 wherein the first sidewall abuts the second sidewall under the predetermined operating condition.

6. The tread as set forth in claim 5 wherein relative motion between the first sidewall and the second sidewall is prevented by a wavy configuration of the first sidewall and a corresponding wavy configuration of the second sidewall.

7. A method for stiffening a tire tread comprising the steps of: extending a first circumferential main groove across the tire tread; extending a second circumferential main groove across the tire tread; circumferentially extending a wavy subgroove across a radially innermost cylindrical bottom surface of the first main groove; and curving a radially innermost surface of the subgroove, the radially innermost surface of the subgroove being radially inside the radially innermost cylindrical bottom surface of the first main groove.

8. The method as set forth in claim 7 wherein curved radially innermost surface of the subgroove mitigates cracking and increases axial flexibility of the first main groove.

9. The method as set forth in claim 8 wherein an axial width of the subgroove shrinks to 0.0 mm under a predetermined operating condition.

10. The method as set forth in claim 9 wherein the subgroove has a first sidewall and a second sidewall interconnected by the curved radially innermost surface of the subgroove.

11. The method as set forth in claim 10 further including the step of abutting the first sidewall against the second sidewall under the predetermined operating condition.

12. The method as set forth in claim 7 wherein relative motion between the first sidewall and the second sidewall is prevented by a wavy configuration of the first sidewall and a corresponding wavy configuration of the second sidewall.

13. A system for increasing cornering stiffness of a tire tread comprising: a first circumferential main groove; a second circumferential main groove; and a stabilizing structure for increasing tread stiffness, the stabilizing structure having a circumferentially extending wavy subgroove in a radially innermost bottom of the first main groove.

14. The system as set forth in claim 13 wherein the subgroove has a curved, cylindrical radially innermost surface for mitigating cracking and increasing axial flexibility of the stabilizing structures.

15. The system as set forth in claim 14 wherein an axial width of the subgroove shrinks to 0.0 mm under a predetermined operating condition.

16. The system as set forth in claim 15 wherein the subgroove has a first sidewall and a second sidewall interconnected by the curved, cylindrical radially innermost surface of the subgroove.

17. The system as set forth in claim 16 wherein the first sidewall abuts the second sidewall under the predetermined operating condition.

18. The system as set forth in claim 17 wherein relative motion between the first sidewall and the second sidewall is prevented by a wavy configuration of the first sidewall and a corresponding wavy configuration of the second sidewall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The present invention will be better understood through reference to the following description and the appended drawings, in which:

[0091] FIG. 1 is a schematic perspective view of a tire in accordance with the present invention.

[0092] FIG. 2 is a schematic orthogonal view of the tread of the tire of FIG. 1.

[0093] FIG. 3 is a schematic detail view of the tread of FIG. 2.

[0094] FIG. 4 is a schematic section view taken along the line 4-4 in FIG. 2.

[0095] FIG. 5 is a schematic detail drawing of a shoulder area of FIG. 4.

DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION

[0096] Referring now in more detail to the drawings, the present invention will below be described in more detail. The pneumatic, or non-pneumatic, tire 10 illustrated in FIGS. 1-5 may have a tread 11 with narrow sacrificial circumferential shoulder ribs 18 defined by circumferential shoulder grooves 28 at the lateral edges of the main tread portion. The shoulder grooves 28 may have curved, cylindrical radially innermost surfaces 29 to mitigate cracking (FIG. 5). The narrow sacrificial shoulder ribs 18 may be radially recessed from the main tread portion. The main tread portion may be defined by intermediate circumferential first ribs 12, intermediate circumferential second ribs 14, and a center intermediate circumferential third rib 16. The intermediate circumferential ribs 12, 14, 16 may be defined by the shoulder grooves 18, two stabilizing circumferential grooves 22, and two central circumferential grooves 24. The two central circumferential grooves 24 may each have a trapezoidal cross-section with slanted walls and a flat bottom (FIG. 4). The intermediate circumferential second ribs 14 and the center intermediate circumferential third rib 16 may have wavy blind sipes 15, 17, respectively, for improving performance of the tread 11.

[0097] The two stabilizing circumferential grooves 22 may also have a trapezoidal cross-section with slanted walls and a flat bottom, similar to the two central circumferential grooves 24. As shown in FIG. 4, the radial depth of each stabilizing grooves 22 may be more shallow or less than the depth of the central circumferential grooves 24. The stabilizing groove depths may be about 50% of the central groove depths (FIG. 4). At the flat bottom of each stabilizing groove 22 may be a stabilizing structure 220. The stabilizing structures 220 may define circumferentially extending wavy subgrooves 222 in the bottoms of the stabilizing grooves 22. As shown in FIG. 3, both the axial width of the subgrooves 222 and the axial width of the wave pattern may be less than the axial width of the bottoms of the stabilizing grooves 22. The subgrooves 222 may have curved, cylindrical radially innermost surfaces 229 to mitigate cracking and to increase axial flexibility of the stabilizing structures 222 (FIG. 5).

[0098] When an axially inward load is placed on the tread 11, such as while the vehicle is cornering, the axial width of the subgrooves 222 may shrink to as little as 0.0 mm (e.g., touching). Because of the wavy pattern of the subgrooves 222, the walls of the subgrooves may interlock thereby preventing relative circumferential movement between the walls of the subgrooves. This may provide an increase in stiffness of the tread 11 while cornering, without requiring increased overall stiffness of the tread during straight line movement of the vehicle.

[0099] During normal running of the vehicle, the narrow sacrificial shoulder ribs 18 may remain recessed to maintain a sharp edge at the axially or laterally outer edges of first ribs 12. The narrow sacrificial shoulder ribs 18 may deflect into the first ribs 12 during lateral maneuvers of the vehicle in order to laterally support the first ribs. These narrow sacrificial shoulder ribs 18 may have a coupling effect with the first ribs 12 to maintain a flat lateral or transverse profile of the footprint of the tread 11. The narrow sacrificial shoulder ribs 18 may wear at essentially the same rate as the main tread portion thereby maintaining a stable radial recess or offset distance from the main tread profile (FIG. 5).

[0100] While the present invention has been described in connection with what is considered the most practical and preferred example, it is to be understood that the present invention is not to be limited to these described examples, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible.