PURPOSE: To heighten the moment of inertia in a tire and make deflection in the handle-bar of a motorcycle smaller as well as to aim at improvements in steering stability and durability in time of driving at high speed, by making up thickness in a tire central part thicker than that of a tread end part.

CONSTITUTION: A tire 1 consists of a tread part 2, a sidewall part 3 extending toward a radial inward direction from both sides of the tread part 2 and a bead part 4 situated in an inside end part of the radial direction. In this case, the ratio of thickness (a) of a tire equatorial surface and thickness (b) of a tread end part is set to a range of 0.30W0.80, while the moment of inertia in a tread central part is made to be higher whereby forward driving stability is improved. In addition, a carcass 5 is made up of two sheets of plies and its both ends get the circumference of a bead core 6 turned up from inside to outside. And, a bead apex 9 is disposed in a direction from the bead core 6 to the sidewall.