| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for a heavy load capable of reducing the weight thereof, while maintaining the high-speed durability and the eccentric wear resistance. SOLUTION: In four belt layers 7 provided in the peripheral side of a carcass layer 4 of a tread part 1, a first belt layer 7A is formed of a nylon belt layer and a second - a fourth belt layers 7B, 7C and 7D are formed of a steel belt layer. A nylon cord or a nylon raw string of the first belt layer 7A has a fineness based on corrected mass of 3,000-10,000 dtex, and arranged at a 0-5 degree inclination against the tire circumferential direction. The steel cord of the second - the fourth belt layers 7B, 7C and 7D has an elongation percentage of 0.4% or less when a load of 300 N is applied, and volume ratio as a ratio of the steel cord in relation to the whole volume of each belt layer 7B, 7C and 7D is set at 12-22%. COPYRIGHT: (C)2003,JPO
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