A pneumatic tire having a tread surface provided with a plurality of circumferential grooves and lateral grooves each having one end opened into that circumferential groove and the other end terminating in a land portion. At least one lateral groove is always included completely in the ground contact surface of the tread. The groove width of the lateral grooves is at least locally not less than 30% of the groove width of the circumferential grooves. Each lateral groove has an extending length not less than 40% of an extending length of the circumferential grooves in the ground contact surface and is provided with a region having a cross-sectional area which increases from its side of opening into the circumferential groove toward its terminal end, and including a starting end with a minimum cross-sectional area that is situated closer to the circumferential groove in which the lateral groove opens.