Patent ID: 8622105
Filing Date: 2014-01-07
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: 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, wherein the first twisted bunches include a low-twist bunch of which first twist number is a minimum value Nmin, and a high-twist bunch of which first twist number is a maximum value Nmax, and the ratio Nmin/Nmax is not less than 0.5 and not more than 0.9, and the second twist number M of the treated bunches is not less than the minimum value Nmin and not more than the maximum value Nmax; whereby the band cord has a load-elongation curve comprising a low-modulus zone between the origin and a boundary point (P) and a high-modulus zone between the boundary point (P) and the breaking point (P 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 boundary point (P) is defined as a point on the load-elongation curve (J) of which elongation percentage is the same as that of an intersecting point (P the nominal elastic modulus EL of the low-modulus zone (S the nominal elastic modulus EH of the high-modulus zone (S the load-elongation curve (J) extends from the boundary point (P) toward the origin (O) asymptotically to the tangential line (T the load-elongation curve (J) extends from the boundary point (P) toward the breaking point (P