PURPOSE: To improve frictional performance on an icy road without any substantial deterioration in the steering performance on a dry road by composing a tread part of two layered structure where a cap tread M is positioned at the outside of a base tread N, and specifying the volume ratio there between and JIS hardness in their rubber compositions respectively.

CONSTITUTION: A tread part 3 is composed of two layered structure where a cap tread M is positioned at the outside of a base tread N. In this case, the ratio M/N between them is set 2/8 to 8/2 (volume ratio). The cap tread M is constituted of a rubber composition A of JIS hardness Hs50 to 68. In this case, the JIS hardness of the rubber composition B is set larger than that of the rubber composition A. The rubber composition A includes a soluble inorganic compound with its particles not being contacted to each other substantially.