A pneumatic tire comprises a tread portion provided with at least two circumferential grooves and lateral grooves extending from the circumferential grooves so as to form blocks which are circumferentially divided by the lateral grooves and arranged in at least three circumferential rows axially divided by said at least two circumferential grooves. Each of the lateral grooves is provided with a tie-bar rising from the groove bottom to a certain height as to connect the opposite groove walls with each other. The tie-bars in the lateral grooves extend towards the adjacent circumferential grooves but terminate before the circumferential grooves so as to provide certain distances therebetween, and the distances are gradually decreased from the axially outside to the axially inside of the tread portion. The inclination angles of the lateral grooves are gradually decreased from the axially outside to the axially inside of the tread portion.