A pneumatic tire having tread blocks provided in the side walls with grooves opened at the top of the block, the depth gW of each groove in the axial direction of the tire being in the range of 5 to 50% of the block width BW, the width gL of each groove in the circumferential direction being in the range of 5 to 25% of the block length BL, the height gH of each groove at the block side wall being in the range of 15 to 80% of the depth GH of a main groove dividing the block, whereby performances on the snowy and icy roads and noise generation and wear resistance on the normal roads are well improved in good balance.