A pneumatic tire having a plurality of main grooves extending in the circumferential direction of a tread surface, and a plurality of auxiliary grooves each of which is disposed in the shape of the letter "V" and extended in one of the circumferential directions of the tread surface, the apexes of the V-shaped auxiliary grooves being distributed in left and right regions each extending from the equator of the tire as much as 5-25% of the width of a ground contacting portion of the tread surface, in such a manner that the numbers of the apexes in the left and right regions become substantially equal to each other, characterized in that quasi-main grooves each of which connects at least two circumferentially arranged auxiliary grooves together are provided in left and right regions each extending from the equator of the tire as much as 25-50% of the width of a ground contacting portion of the tread surface, in such a manner that the quasi-main grooves are inclined at an angle of 5.degree.-25.degree. with respect to the equator of the tire.