| 摘要 |
PURPOSE:To improve the rotational resistance without loosing the steering stability by constituting a belt layer of cord-shaped fiber reinforcing material which is made by impregnating thermoplastic resin having specific property by the specified amount into a bundle of cord-shaped fibers constituted of a large number of filaments having specific property. CONSTITUTION:A filament having the specific gravity below 3.0 and tensile strength of 10g/d or more and tensile elastic modulus of 200g/d or more, e.g., alamide fibers are bundled in a large number to form a bundle of cord-shaped fibers. And it is impregnated with thermoplastic resin having tensile elastic modulus of 10kg/mm<2> or more, e.g., nylon by 15% or more by weight to form a cord-shaped fiber reinforcing material. A belt layer is constituted of this cord-shaped fiber reinforcing material. By this constitution, the rotational resistance can be improved without loosing the steering stability.
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