TYRE STEEL REINFORCEMENT

摘要

A radial tire has a combined reinforcement consisting of a belt composed of at least three piled cord layers with steel cords buried in parallel in rubber in which the cords in each of the layers are set at a relatively small angle with respect to a tire equatorial plane and the cords in at least one pair of the adjacent cord layers are intersectingly arranged at an angle from 15 DEG to 30 DEG and a carcass having cords arranged substantially at right angles with respect to the tire equatorial plane. The steel cords buried in the at least one pair of the cord-intersecting cord layers other than the outermost cord layer have Young's modulus of 6,000 to 16,000 kg/mm2 and a flexural rigidity of 150 to 250 g, and the initial stage elongation (P.L.E.) of the rubberized cords taken out from the tire is not more than 0.2%. A tire reinforcing steel cord of a two layer twisted construction is also disclosed, which cord is composed of a core consisting of from two to four steel filaments and a single sheath consisting of a plurality of the steel filaments surrounding the core in which the steel filaments have a tensile strength of not lower than 260 kg/mm2 and a filament diameter of from 0.32 to 0.42 mm; the twisting direction of the core is reversed to that of the sheath; the twisting angle of the sheath, P2, is 72 DEG