PNEUMATIC TIRE

• US 20100116395A1
• Filed: 03/11/2008
• Published: 05/13/2010
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Andou, Shuji
• Granted Patent: US 8,794,279 B2
• Time in Patent Office: Days
• US Class Current: 152/209.250
• CPC Class Codes: B60C 11/01 Shape of the shoulders between tread and sidewall, e.g. rounded, stepped or cantilevered
• CPC Class Codes: B60C 11/0323 tread comprising channels under the tread surface, e.g. for draining water
• CPC Class Codes: B60C 11/1323 asymmetric
• CPC Class Codes: B60C 2011/013 provided with a recessed portion
• CPC Class Codes: B60C 2011/0348 Narrow grooves, i.e. having a width of less than 4 mm

Abstract

A thin groove 4 that continuously extends in the tread circumferential direction is provided in a shoulder rib 3. An annular groove 8 continuous in the circumferential direction is provided in a groove wall 4a on the tread equatorial surface side of the thin groove 4 to be contiguous to the groove bottom, in a cross section taken in the width direction of the tread. The shape of the annular groove in a cross section taken in the width direction of the tread is formed such that a corner portion contiguous to the groove wall on the tread equatorial surface side is rounded to a curvature radius R1, a corner portion of the innermost portion of the annular groove that is in the outer side portion in the tire radial direction is rounded to a curvature radius R2, a corner portion of the innermost portion of the annular groove that is in the inner side portion in the tire radial direction is rounded to a curvature radius R3, and a corner portion contiguous to a groove wall 4b on the tread end side is rounded to a curvature radius R4. According to the present invention, it is possible to improve the stone trapping resistance, tear resistance of defense grooves, and groove bottom crack resistance.

Claims

1. A pneumatic tire comprising a thin groove that continuously extends in the tread circumferential direction in a shoulder rib that is demarcated to the tread edge side portion by a circumferential direction main groove that is continuous in the tread circumferential direction, the pneumatic tire comprises:

an annular groove provided continuously in the circumferential direction in a groove wall on the tread equatorial surface side of the thin groove, which is formed facing the normal direction of the tread surface, to be contiguous to the groove bottom, in a cross section taken in the width direction of the tread;

wherein

the shape of the annular groove in a cross section taken in the width, direction of the tread is formed such that a corner portion contiguous to the groove wall on the tread equatorial surface side is rounded to a curvature radius R1, a corner portion of the innermost portion of the annular groove that is in the outer side portion in the tire radial direction is rounded to a curvature radius R2, a corner portion of the innermost portion of the annular groove that is in the inner side portion in the tire radial direction is rounded to a curvature radius R3, and a corner portion contiguous to a groove wall on, the tread end side is rounded to a curvature radius R4.

2. The pneumatic tire according to claim 1, further comprising a straight portion or a curved portion having a curvature radius that differs from the curvature radii of the corner portions interposed between the corner portions.

3. The pneumatic the according to claim 1, wherein the curvature radius R1 is set to a range of 1.0 mm to 12.0 mm, the curvature radius R2 is set to a range of 1.5 mm to 4.0 mm, the curvature radius R3 is set to a range of 1.0 mm to 6.0 mm, and the curvature radius R4 is set to a range of 2.0 mm to 16.0 mm.

4. The pneumatic tire according to claim 1, wherein the width of the annular groove measured from the groove wall on the tread equatorial surface side in a cross section taken in the tread width direction is set to a range of 1 to 5 times the width of the thin groove.

5. The pneumatic tire according to claim 1, wherein the depth of the thin groove is in a range of 0.3 to 1.5 times the depth of the circumferential direction main groove, and the width of the thin groove is in a range of 0.3 mm to 5.0 mm.

6. The pneumatic tire according to claim 2, wherein the width of the annular groove measured from the groove wall on the tread equatorial surface side in a cross section taken in the tread width direction is set to a range of 1 to 5 times the width of the thin groove.

7. The pneumatic tire according to claim 2, wherein the depth of the thin groove is in a range of 0.3 to 1.5 times the depth of the circumferential direction main groove, and the width of the thin groove is in a range of 0.3 mm to 5.0 mm.

8. The pneumatic tire according to claim 3, wherein the depth of the thin groove is in a range of 0.3 to 1.5 times the depth of the circumferential direction main groove, and the width of the thin groove is in a range of 0.3 mm to 5.0 mm.