Pneumatic tire

• US 20050103419A1
• Filed: 03/26/2003
• Published: 05/19/2005
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Yamamoto, Emiko
• Granted Patent: US 6,938,660 B2
• Time in Patent Office: Days
• US Class Current: 152/557
• CPC Class Codes: B60C 13/00 Tyre sidewalls; Protecting, decorating, marking, or the like, thereof B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01
• CPC Class Codes: B60C 15/06 Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
• CPC Class Codes: B60C 2013/007 Thickness
• CPC Class Codes: B60C 9/02 Carcasses
• CPC Class Codes: Y10T 152/10819 Characterized by the structure of the bead portion of the tire
• CPC Class Codes: Y10T 152/10837 Bead characterized by the radial extent of apex, flipper or chafer into tire sidewall
• CPC Class Codes: Y10T 152/10873 with two or more differing cord materials

Abstract

A pneumatic tire, comprising a carcass having a carcass ply_(6a) with a folded part (6b) folded up around a bead core (5) from the axial inside to the axial outside of the tire continuously fitted to a ply body part (6a) installed across the bead cores (5) and (5), wherein the intermediate elongation (Es) of a carcass cord in the ply body part (6a) at the maximum width position (M) is smaller than the intermediate elongation (Eb) thereof at the height position (B) of the bead core at the radial outermost end of the tire.

Claims

1. A pneumatic tire, comprising a carcass including a carcass ply having a ply body portion which extends from a tread portion to a bead core of a bead portion through a sidewall portion and which is continuously provided with a ply folded-up portion folded up around the bead core from its inner side to its outer side in the tire axial direction, wherein

an intermediate elongation Es of a carcass cord in the ply body portion at a maximum width position where the ply body portion projects most outward in a tire axial direction is smaller than an intermediate elongation Eb at a height position of a radially outermost end of the bead core.

2. The pneumatic tire according to claim 1, wherein a ratio (Es/Eb) of the intermediate elongation Es at the maximum width position and the intermediate elongation Eb at the height position of the outermost end is higher than 0.7 and smaller than 0.9.

3. The pneumatic tire according to claim 1 or 2, wherein the ratio (Es/Eb) of the intermediate elongation Es at the maximum width position and the intermediate elongation Eb at the height position of the outermost end is in a range of 0.75 to 0.85.

4. The pneumatic tire according to claim 1, wherein a bead apex rubber extending radially outward of the tire from a radially outer surface of the bead core is disposed in the bead portion, a height (ha) of the bead apex rubber from a bead base line is 0.3 to 1.0 times a height (h) from the bead base line to the maximum width position.

5. The pneumatic tire according to claim 1, wherein a tire thickness Ts of the sidewall portion at the maximum width position of the carcass ply is 30 to 67% of a tire thickness Tb of the bead core at the height position of the outermost end.

6. The pneumatic tire according to claim 1, wherein the carcass cord is a polyester cord, the intermediate elongation Es is 3.0 to 5.0%.

7. The pneumatic tire according to claim 1, wherein the tread portion is provided with a belt layer radially outward of the carcass, and a ratio (Ef/Es) of an intermediate elongation Ef of the carcass cord at a position of an outer end of the belt layer and an intermediate elongation Es at the maximum width position is 0.6 to 0.95.

8. The pneumatic tire according to claim 7, wherein a ratio (Ef/Es)/(Es/Eb) of the ratio (Ef/Es) and the ratio (Es/Eb) is 0.80 to 1.20.