Pneumatic tire

• US 20060011280A1
• Filed: 07/14/2005
• Published: 01/19/2006
• Est. Priority Date: 07/16/2004
• Status: Active Grant

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Yagita, Masanori
• Granted Patent: US 7,669,624 B2
• Time in Patent Office: Days
• US Class Current: 152/209.240
• CPC Class Codes: B60C 11/0306 Patterns comprising block rows or discontinuous ribs
• CPC Class Codes: B60C 11/042 further characterised by the groove cross-section
• CPC Class Codes: B60C 11/13 characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping
• CPC Class Codes: B60C 11/1323 asymmetric
• CPC Class Codes: Y10S 152/901 Tread pattern having no blocks and having circumferential ribs defined by linear circumferential grooves having straight edges

Abstract

A pneumatic tire includes a tread surface on which a plurality of circumferential groove portions is formed. From among circumferential groove portions, a circumferential groove portion situated closest to a shoulder portion side in a tire width direction has a center of a groove-bottom innermost portion at a portion where a groove width in at least a tire circumferential direction is the narrowest, positioned closer to an equatorial surface in the tire width direction than a center of the groove width. An angle between a virtual extension portion of the tread surface and a groove wall on the equatorial surface side is equal to or less than an angle between the virtual extension portion of the tread surface and a groove wall on the shoulder portion side.

Claims

1. A pneumatic tire comprising a tread surface on which a plurality of circumferential groove portions is formed, wherein

from among the circumferential groove portions, a circumferential groove portion situated closest to a shoulder portion side in a tire width direction has a center of a groove-bottom innermost portion at a portion where a groove width in at least a tire circumferential direction is the narrowest, the center of the groove-bottom innermost portion being positioned closer to an equatorial surface in the tire width direction than a center of the groove width, and

a first angle between a virtual extension portion of the tread surface and a groove wall on the equatorial surface side is equal to or less than a second angle between the virtual extension portion of the tread surface and a groove wall on the shoulder portion side.

2. The pneumatic tire according to claim 1, wherein the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a curved surface that is recessed to the groove wall on the equatorial surface side.

3. The pneumatic tire according to claim 1, wherein the center of the groove-bottom innermost portion is positioned closer to the equatorial surface by 5% or more of the groove width than the center of the groove width.

4. The pneumatic tire according to claim 1, wherein

the first angle is in a range of 45 degrees to 75 degrees,

the second angle is in a range of 75 degrees to 110 degrees, and

a ratio of the first angle to the second angle is in a range of 0.5 to 0.95.

5. The pneumatic tire according to claim 1, wherein

the groove wall on the equatorial surface side is formed with a plurality of planes, and

angles between each of the planes and the virtual extension portion of the tread surface in a depth direction of a groove are different.

6. The pneumatic tire according to claim 5, wherein

the groove wall on the equatorial surface side is formed with two planes,

angles between each of the two planes and the virtual extension portion of the tread surface in the depth direction of a groove are different, and

a joint portion of the two planes is formed at a position where a distance of the joint portion from the tread surface in the depth direction of the circumferential groove portion is a half of the groove depth of the circumferential groove portion.

7. The pneumatic tire according to claim 1, wherein

the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a shoulder-portion-side curved surface that is a curved surface recessed to the groove wall on the equatorial surface side,

the groove-bottom innermost portion and the groove wall on the equatorial surface side are connected by an equatorial-surface-side curved surface that is a curved surface recessed to the groove wall on the shoulder portion side, and

in the shoulder-portion-side curved surface and the equatorial-surface-side curved surface when viewed as a cross-section in a meridian direction, a first radius of a curved line forming the shoulder-portion-side curved surface is larger than a second radius of a curved line forming the equatorial-surface-side curved surface.

8. The pneumatic tire according to claim 1, wherein

the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a shoulder-portion-side curved surface that is a curved surface recessed to the groove wall on the equatorial surface side, and

a joint portion of the groove wall on the shoulder portion side and the shoulder-portion-side curved surface is formed at a position where a distance of the joint portion from the tread surface in the depth direction of the circumferential groove portion is about a half of the groove depth of the circumferential groove portion.

9. A pneumatic tire comprising a tread surface on which a plurality of circumferential groove portions is formed, wherein

from among the circumferential groove portions, a circumferential groove portion situated closest to a shoulder portion side in a tire width direction has a center of a groove-bottom innermost portion at a portion where at least a groove width on the shoulder portion side is closest to an equatorial surface in the tire width direction, the center of the groove-bottom innermost portion being positioned closer to the equatorial surface than a center of the groove width, and

a first angle between a virtual extension portion of the tread surface and a groove wall on the equatorial surface side is equal to or less than a second angle between the virtual extension portion of the tread surface and a groove wall on the shoulder portion side.

10. The pneumatic tire according to claim 9, wherein the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a curved surface that is recessed to the groove wall on the equatorial surface side.

11. The pneumatic tire according to claim 9, wherein the center of the groove-bottom innermost portion is positioned closer to the equatorial surface by 5% or more of the groove width than the center of the groove width.

12. The pneumatic tire according to claim 9, wherein

the first angle is in a range of 45 degrees to 75 degrees,

the second angle is in a range of 75 degrees to 110 degrees, and

a ratio of the first angle to the second angle is in a range of 0.5 to 0.95.

13. The pneumatic tire according to claim 9, wherein

the groove wall on the equatorial surface side is formed with a plurality of planes, and

angles between each of the planes and the virtual extension portion of the tread surface in a depth direction of a groove are different.

14. The pneumatic tire according to claim 13, wherein

the groove wall on the equatorial surface side is formed with two planes,

angles between each of the two planes and the virtual extension portion of the tread surface in the depth direction of a groove are different, and

a joint portion of the two planes is formed at a position where a distance of the joint portion from the tread surface in the depth direction of the circumferential groove portion is a half of the groove depth of the circumferential groove portion.

15. The pneumatic tire according to claim 9, wherein

the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a shoulder-portion-side curved surface that is a curved surface recessed to the groove wall on the equatorial surface side,

the groove-bottom innermost portion and the groove wall on the equatorial surface side are connected by an equatorial-surface-side curved surface that is a curved surface recessed to the groove wall on the shoulder portion side, and

in the shoulder-portion-side curved surface and the equatorial-surface-side curved surface when viewed as a cross-section in a meridian direction, a first radius of a curved line forming the shoulder-portion-side curved surface is larger than a second radius of a curved line forming the equatorial-surface-side curved surface.

16. The pneumatic tire according to claim 9, wherein

the groove-bottom innermost portion and the groove wall on the shoulder portion side are connected by a shoulder-portion-side curved surface that is a curved surface recessed to the groove wall on the equatorial surface side, and

a joint portion of the groove wall on the shoulder portion side and the shoulder-portion-side curved surface is formed at a position where a distance of the joint portion from the tread surface in the depth direction of the circumferential groove portion is about a half of the groove depth of the circumferential groove portion.