Pneumatic tire

• US 10,639,940 B2
• Filed: 08/22/2017
• Issued: 05/05/2020
• Est. Priority Date: 12/02/2016
• Status: Active Grant

• Current Assignee: TOYO Tire & Rubber Company Limited
• Original Assignee: Toyo Tire Corporation
• Inventors: Miyake, Akinori
• Primary Examiner(s): Dye, Robert C
• Assistant Examiner(s): Taufiq, Farah
• Application Number:
  US15/683,204
• Publication Number:
  US 20180154702A1
• Time in Patent Office: 987 Days
• CPC Class Codes: B60C 11/01 Shape of the shoulders between tread and sidewall, e.g. rounded, stepped or cantilevered
• CPC Class Codes: B60C 11/1323 asymmetric
• CPC Class Codes: B60C 11/1353 with special features of the groove bottom
• CPC Class Codes: B60C 2011/013 provided with a recessed portion
• CPC Class Codes: B60C 2011/0346 with zigzag shape
• CPC Class Codes: B60C 2011/0348 Narrow grooves, i.e. having a width of less than 4 mm

Abstract

A shoulder land portion is sectioned into a main land portion and a sacrificed land portion by a narrow groove extending in a tire circumferential direction. A groove bottom portion of the narrow groove is formed by depressing a groove wall in the tread center side. A contour of the main land portion is formed by a first circular arc in a tread center side and a second circular arc in a tread end side. A radius of curvature R1 of the first circular arc is less than a radius of curvature R2 of the second circular arc. A ratio W/d satisfies a relationship 2≤W/d≤6. The d is a depression width of a groove bottom portion. The W is a distance from a tread end side edge of the main land portion to a boundary between the first circular arc and the second circular arc.

Claims

1. A pneumatic tire comprising a narrow groove which extends in a tire circumferential direction, the narrow groove being formed in a shoulder land portion of a tread, the shoulder land portion being sectioned into a main land portion in a tread center side and a sacrificed land portion in a tread end side by the narrow groove, the main land portion having a continuous contour of a ground surface,

wherein a groove bottom portion of the narrow groove is formed by depressing a groove wall in the tread center side,

wherein the continuous contour of the ground surface of the main land portion is formed by a first circular arc in the tread center side and a second circular arc in the tread end side, the first circular arc and the second circular arc are connected to each other, and a radius of curvature R1 of the first circular arc is less than a radius of curvature R2 of the second circular arc,

wherein a ratio W/d satisfies a relationship 2≤

W/d≤

6 in which d is a depression width of a groove bottom portion on the basis of the groove wall of the narrow groove in the tread center side, W is a distance from a tread end side edge of the main land portion to the boundary between the first circular arc and the second circular arc, and the ratio W/d is a ratio of the distance W in relation to the depression width d,

wherein the boundary between the first circular arc and the second circular arc is arranged in a center region of the main land portion, and

wherein a ratio W/W21 of the distance W in relation to a width W21 of the main land portion satisfies a relationship 0.1≤

W/W21≤

0.5.

2. The pneumatic tire according to claim 1, wherein a ratio R2/R1 satisfies a relationship 1.5≤

R2/R1≤

2.5 in which the ratio R2/R1 is a ratio of the radius of curvature R2 in relation to the radius of curvature R1.

3. The pneumatic tire according to claim 1, wherein the groove bottom portion of the narrow groove is formed by depressing only the groove wall in the tread center side of the groove wall in the tread center and a groove wall in the tread end side.

4. The pneumatic tire according to claim 1, wherein an inside concave curved surface obtained by depressing the groove wall in the tread center side is formed in the groove bottom portion of the narrow groove, and

wherein the inside concave curved surface is formed by a flection surface which is depressed to an inner side in a tire width direction and is formed into a circular arc cross section, and is extended annularly along the tire circumferential direction.

5. The pneumatic tire according to claim 1, wherein the depression width d is set between 0.5 and 6.0 mm.

6. The pneumatic tire according to claim 1, wherein the shoulder land portion is positioned between a tread end and a shoulder main groove positioned in the outermost side in a tire width direction.

7. The pneumatic tire according to claim 6, wherein the narrow groove is formed narrower than the shoulder main groove on a ground surface of the tread.