| 摘要 |
PURPOSE:To produce a pneumatic radial tire having performance characteristics on an icy road equivalent to those of a spiked tire without detriment to the braking characteristics, driving stability, and abrasion resistance on wet and dry roads. CONSTITUTION:A pneumatic radial tire is produced by using a tread made from a closed cell foam which has an expansion ratio of 5-50% and an average cell diameter of 1-120mum and is obtd. from a rubber compsn. obtd. by compounding 100 pts.wt. conjugated diene rubber with 30 pts.wt. or higher conjugated diene block copolymer. The block copolymer is obtd. by copolymerizing a conjugated diene compd. with an arom. vinyl compd. using a lithium-based initiator, has a total vinyl bond content of 20-70% and a total arom. vinyl compd. content of 5-40%, and consists of 15-85wt.% random copolymer block (A) and 85-15wt.% random copolymer block (B) each having a vinyl bond content in the diene parts and an arom. vinyl compd. content different from the other. The copolymer block A has a vinyl bond content in the diene parts of 20% or higher and an arom. vinyl compd. content of 30% or lower while the copolymer block B has a vinyl bond content in the diene parts of 60% or lower and an arom. vinyl compd. content of 50% or lower. |
