Heavy-duty radial snow tire

Claim 1

A radial snow tire for heavy vehicles comprising a tread formed with (1) transverse zigzag grooves extending from one edge of the tread to the other and spaced apart at regular intervals in the longitudinal direction and (2) substantially longitudinal linear grooves connecting adjacent transverse grooves and having a width less than that of the transverse grooves, the transverse and longitudinal grooves together defining an array of isolated blocks and the longitudinal grooves being spaced apart at regular intervals in a succession of transverse rows but being staggered on opposite sides of each transverse groove in an asymmetrical fashion, so that, except for alternate blocks at the edges of the tread, each block is overlapped by the longitudinally adjacent blocks over unequal fractions of its transverse dimension, one fraction being at least twice the other, the walls of the longitudinal grooves forming angles with the perpendicular to the tread surface smaller than the angles formed by the walls of the transverse grooves with the perpendicular to the tread surface, and, in the case of each block except alternate blocks at the edges of the tread, the end overlapped by the larger fraction of the transverse dimension of such block including a wall forming with the perpendicular to the tread surface an angle a, and the end overlapped by the smaller fraction of the transverse dimension of such block including a wall forming with the perpendicular to the tread surface an angle b, the angle a being larger than the angle b.