Patent ID: 8104525
Filing Date: 2012-01-31
Classification: B60C,D02G,Y10T

Abstract:
1. A pneumatic tire comprising a carcass extending between a pair of bead portions through a tread portion and a pair of sidewall portions, and a band made of at least one spirally wound cord disposed radially outside the carcass in the tread portion, wherein the band cord consists of materially identical high-strength high-modulus organic filaments, and the band cord is obtainable by the following process (1) or (2): (1) the high-modulus organic filaments are divided into a plurality of bunches, the bunches are each first twisted separately from each other, the first twisted bunches are each subjected to a dip-and-stretch treatment, and the treated bunches are second twisted together; or (2) the high-modulus organic filaments are divided into a plurality of bunches, the bunches are each first twisted separately from each other, the first twisted bunches are each subjected to a dip-and-stretch treatment, some of the treated bunches are second twisted together to form a core, and at least one remaining treated bunch is spirally wound around the core, whereby the band cord has a load-elongation curve comprising a low-modulus zone between the origin and a boundary point and a high-modulus zone between the boundary point and the breaking point, and the boundary point is at a certain elongation in a range of from 1 to 7%, and the ratio EH/EL of a nominal elastic modulus EH of the high-modulus zone and a nominal elastic modulus EL of the low-modulus zone is in a range of from 2.0 to 10.0, wherein the load of the band cord at 1% elongation is in a range of from 20 to 60 N, and the load of the band cord at 3% elongation is in a range of from 225 to 431 N.