Patent ID: 7712499
Filing Date: 2010-05-11
Classification: B29D,B60C,D02G,D10B,Y10T

Abstract:
1. A pneumatic radial tire comprising a pair of bead cores, a carcass layer comprising one or more carcass plies extending from one of the bead cores to the other bead core in a toroidal form, and a belt layer comprising at least one belt ply including an organic fiber cord on an outer peripheral surface of a crown region on an outer side of the carcass layer in a radial direction of the tire, wherein the belt layer comprises a main belt layer formed of at least two belt plies including an organic fiber cord having a tensile fracture strength of 6.3 cN/dtex or higher, an elongation percentage of 0.2 to 2.0% when 0.3 cN/dtex load is applied in an elongating direction, an elongation percentage of 1.5 to 7.0% when 2.1 cN/dtex load is applied in the elongating direction, and an elongation percentage of 2.2 to 9.3% when 3.2 cN/dtex load is applied in the elongating direction, and an auxiliary belt layer provided at an outer side of the main belt layer in the radial direction of the tire and comprising a belt ply including an organic fiber cord whose elongation percentage when 2.1 cN/dtex load is applied is greater than that of the organic fiber cord included in the belt ply of the main belt layer, whose angle with respect to the tire equator surface is substantially equal to or greater than that of the organic fiber cord included in the belt ply of the main belt layer, and the organic fiber cord included in the belt ply of the auxiliary belt layer is a different kind of cord material from the organic fiber cord included in the belt ply of the main belt layer, and when a total strength of the belt layer in a circumferential direction of the tire per unit of width at a tire equator surface position P