| 摘要 |
PURPOSE:To make a tire lightweight and make rim mounting easy by making a nonmetallic high strength fiber bundle having specified values in specific gravity, tensile elastic modulus, and breaking elongation a core member, and winding a steel wire in a spiral state on the outer side thereof so as to be in a specific volume percent to form a bead core. CONSTITUTION:A core member 7 of a bead core 2 is formed of a nonmetallic high strength fiber 3.0 or less in specific gravity, 7000-31000 kgf/mm<2> in tensile elastic modulus, 1.2-4.2% in breaking elongation, for instance, aramid fiber is drawn arranged in order in nontwisted state. A steel wire 8 is wound in a spiral state so as to be 0.25-0.72 in volume percent on the outer side of the core member 7, to form the bead core 2. It is possible thereby to improve tensile strength of a whole bead core with the steel wire and the nonmetalic high strength fiber bundle. |
