PNEUMATIC TIRE PROVIDED WITH DIRECTIONAL TREAD

PURPOSE:To improve mainly high speed durability by forming the shapes of wall and bottom parts of both circumferential grooves and lateral grooves dividing blocks such that the previously grounding side has a radius of curvature smaller than the subsequently grounding side. CONSTITUTION:The tread of a tire comprises a plurality of circumferential grooves, lateral grooves 2 arranged like the nock of an arrow and having a U-shaped section and blocks 3 divided by these grooves. The rotational direction of the tire is set such that the central tread part of the lateral groove 2 grounds previously and both ends of the tread ground later. Then, respective forms of groove wall and bottom of the lateral groove 2 are set such that the radius of curvature R1 of the previous ground contacting side(kicking-out side) 2A is smaller than that R2 of the later ground contacting side 2b, particularly R2/R1 = 2-5 for example. Thus, the stress concentration in the load rolling is mitigated and the occurrence of cracks in high speed travelling is prevented.