| abstract |
(57) [Problem] To provide a rubber composition having excellent low-temperature rebound resilience and tensile stress, and having sufficient flex fatigue resistance and a wear index. SOLUTION: (i) (A) a conjugated diene-based polymer segment 10 having a high cis content of 40% or more; A partially crystalline block copolymer rubber comprising 98% by weight and (B) 90 to 2% by weight of a crystalline segment, having a molecular weight distribution of 4 or less and a weight average molecular weight in terms of polystyrene of 20,000 to 10,000. A conjugated diene-based rubber composition containing a crystalline segment, comprising: a block copolymer rubber of 1,000,000 and (ii) a reinforcing agent. |