Steel cords for the reinforcement of rubber articles and heavy duty pneumatic radial tires using the same

Abstract

A rubber article-reinforcing steel cord includes a core obtained by forming a single filament in a wavy shape, an inner sheath formed by arranging 5 to 6 filaments around the core, and an outer sheath formed by arranging 9 to 12 filaments around the inner sheath. The inner sheath and said outer sheath are twisted together. The diameter of each of the filaments of the inner and outer sheaths is not greater than that of the filaments of the core, 5d .ltoreq.L.ltoreq.3d and 1.2.ltoreq.H.ltoreq.d2.0d in which L and H are a wave length and a wave height of a wave shape of the waved filaments of the core, respectively, and d is a diameter of the filament of the core, and a ratio p.sub.3 /p.sub.2 between the twisting pitch p.sub.2 of the inner sheath and the twisting pitch p.sub.3 of the outer sheath is in a range of 1.4 to 2.5. A heavy duty pneumatic radial tire is also disclosed, which uses such steel cords in a belt.

Dependencies are inferred from the claim text.