Abstract: A novel rubber composition is obtained by blending a rubber mixture consisting of 15 to 50 parts by weight of 1,2-polybutadiene having a 1,2-addition unit content of 70% or more, a crystallinity of 5 to 40% and an intrinsic viscosity [.eta.] of 0.7 dl/g or more (as measured in toluene at 30.degree. C.) and 85 to 50 parts by weight of at least one rubber selected from the group consisting of natural rubber and diene-based rubbers with 3 to 10 parts by weight of sulfur per 100 parts by weight of said rubber mixture. Said rubber composition has a desirable processability and exhibits, on curing, high hardness, high modulus, low temperature dependency of physical properties, low heat generation and excellent blow-out resistance. It is suitable as a rubber material for use in various low profile automobile tires such as radial tires.