PURPOSE: To improve straight stability on the inclined road surface of a tire whose flatness is small and restrain wandering by arranging inclined slender grooves in the prescribed direction, in the tread end part of a flat surface tread contact range in a prescribed condition.

CONSTITUTION: A land part partitioned by peripheral grooves 6 and auxiliary peripheral grooves 7 is partitioned into blocks 9, 10 by lateral grooves 8, and a land part partitioned by the auxiliary peripheral grooves 7 and tread ends is partitioned into blocks 12 by lateral grooves 11 to form slender grooves 13. When this tire is filled with prescribed inner pressure and is brought into ground contact with a flat surface with prescribed load applied, the slender grooves are formed into substantially inclined grooves whose groove walls extend in the opposite direction to the rotational direction of the tire in a tread end part range Ts which extends to the outside of a tread contact range TM. It is thus possible to improve straight stability on an inclined road surface which has roughness such as a wheel track in a high-quality tire whose flatness is small.