Radial tire with three layer multi-sheath steel carcass cords

摘要

A steel cord for the reinforcement of rubber article has a three- layer twisting construction comprising a core layer comprised of a single steel filament, a first sheath layer comprised of six steel filaments and a second sheath layer comprised of steel filaments subtracted by 1 or 2 filament from maximum steel filament number arranged on a circumscribed circle of the first sheath layer without a wrap filament. In this steel cord, filament diameters of the core layer and the sheath layers satisfy the particular relationships. The steel cord is used in a carcass ply of a heavy duty pneumatic radial tire.