Patent ID: 8746303

Claim:
A pneumatic tire having a small block group in at least a part of a tread portion, the small block group including a plurality of small blocks arranged close together, the small blocks being independently defined by grooves and queuing up a plurality of block rows extending in a tread circumferential direction, comprising: at least one circumferential main groove positioned in the small block group, the circumferential main groove including see-through groove portion, the see-through groove portion linearly extending in the tread circumferential direction; at least one rib-like land portion provided adjacently to the circumferential main groove, the rib-like portion forming a groove side face of the circumferential main groove and continuously extending in the circumferential direction; and a number density D of the small blocks is set within a range of 0.003 to 0.04 (pieces/mm 2 ), the number density D representing the number of the small blocks per unit of an actual ground contact area of the small block group and obtained by a formula: D=a/{PL×W×(1−N/100)−S}, wherein PL (mm) represents a reference pitch length of the small blocks in the small block group, W (mm) represents a width of small the block group, a (pieces) represents the number of the small blocks existing in a reference zone of the small block group, the reference zone is demarcated by the reference pitch length PL and the width W, N (%) represents a negative ratio in the reference zone, and S (mm 2 ) represents a surface area of the rib-like land portion existing in the reference zone, and wherein a distance between adjacent small blocks (BGL) in the tread circumferential direction is larger than a distance between adjacent small blocks (BGO) in an oblique direction with respect to the tread circumferential direction.