PURPOSE: To improve resistance to a thermo-hardening property of a pneumatic type, by making the tread part and the side wall part of a tire of rubber composition which is rubber constituent of polyisoprene rubber alone or mixed with other diene rubber, blended with specific, organic sulfur-curable promotor.

CONSTITUTION: A rubber composition is prepared by blending 0.1W4.0 weight rate of organic sulfur-curable promotor of which general Formula and structural Formula are specified, N-cyclohexyl-4-methylbenzozyl sulfane amide, or the like, for instance, to 100wt rate of rubber constituent of polyisoprene rubber alone or blended with more than one other diene rubber. The tread part and the side wall part of a tire are made of the above-mentioned rubber composition. With such an arrangement, resistance to a thermo-hardening property of a tire during running can be improved, at the same time, the outer view of a tire in the last period of running can be improved.