To provide a diene-based rubber composition which is improved well-balancedly in the heat resistance, the compression set-resistant characteristics and the durability and which is suitably used for the rim cushion parts of a tire.

The diene-based rubber composition comprises a blend of 10-70 pts.wt. of a bituminous coal pulverizate and 0-110 pts.wt. of a carbon black based on 100 pts.wt. of a diene-based rubber, with a weight ratio of a vulcanization accelerator/a sulfur being 0.8-1.5, and with the sum total blending quantity of the bituminous coal pulverizate and the carbon black being not more than 130 pts.wt. The diene-based rubber composition is made to improve well-balancedly the heat resistance, the compression set-resistant characteristics and the durability, and therefore is used suitably as a vulcanizable molding material for the rim cushion parts of a pneumatic tire.