| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic radial-ply tire capable of accomplishing good high-speed running durability on the basis of the thermal shrinkage of fiber threads in which attention is paid to the number of first twists, the number of final twists, and the twist coefficient of the final twists of those fiber threads (twin twisted thread) used in a belt reinforce layer as reinforcing cords. SOLUTION: The pneumatic radial-ply tire using organic thermal shrinking fibers in the belt reinforce layer is structured so that first twists are set on the fiber yarns of the organic thermal shrinking fibers, a plurality of first twist threads are drawn in alignment, and the final twists are set in the opposite direction to the twisting direction of the first twists, wherein cords consisting of twin twisted threads whose number T<SB>1</SB>of first twists, number T<SB>2</SB>of final twists, and twist coefficient k of the final twists meet Eqs. (1) and (2) as follows, are used in the belt reinforce layer; Eq (1) appears as 1.75≤T1/T2≤3.50, while Eq (2) appears as 1500≤K=T<SB>2</SB>√D≤4700, where D represents the fiber fineness (total indication decitex), and the number of twists is expressed by the unit of turns/10cm. COPYRIGHT: (C)2005,JPO&NCIPI
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