Pneumatic tyres for a vehicle

The tire has tread rib (1) that is extended in circumferential direction and provided with U-grooves (8,9) which are arranged adjacent to each other and over periphery of tire. The U-grooves are extended from groove (16) under steady increase in groove depth on peripheral segment (25) of the tire. The transverse grooves (10,11) are provided at extending end of U-grooves in transverse direction.