PURPOSE: To enhance a straight running property and driving stability by enabling a remaining cornering force resulting from pattern factors to be eliminated even with a tire having asymmetrical portions on its tread pattern on the right and left of its axis.

CONSTITUTION: A tread 2 has circumferentially extending longitudinal grooves 4 therein and lateral grooves 5 crossing the longitudinal grooves, and is vitually divided by a tire-axis reference line L into an even number of reference-line sections, and in one of the reference-line area (SA) lateral grooves 5 are inclined at an angle which gradually increases toward the reference line, is greatest at the middle point M, and gradually decreases beyond the middle point. In other reference area adjacent that reference area, lateral grooves are inclined at an angle which gradually increases and decreases in the direction opposite to the inclination of the lateral grooves in the area SA.