To obtain a pneumatic radial tire improved in drive stability and durability by blending a specific compsn. contg. polyamide short fibers in a carcass cord compound.
Polyamide short fibers having an average diameter smaller than 1μm and an average length of 100 to 2,000μm are dispersed in a diene rubber to prepare a compsn. wherein the polyamide short fibers are chemically bonded to the diene rubber. Alternatively, such polyamide short fibers and a polyisoprene rubber and/or natural rubber are dispersed in a continuous phase of a polyolefin to prepare a compsn. wherein they are mutually chemically bonded. One of these compsns. is blended with a diene rubber to prepare a rubber compsn. wherein the amt. of the polyamide short fibers is 0.5 to 15 pts.wt. per 100 pts.wt. rubber, provided that the amt. of the polyolefin is 0.5 to 15 pts.wt. per 100 pts.wt. whole rubber component in the case of the latter compsn. A tire carcass portion is constituted of this rubber compsn. to form a pneumatic radial tire.
NAKAKITA KAZUMASA
OCHIAI TETSUO
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