Pneumatic tire

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/mm2), 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 (mm2) represents a surface area of the rib-like land portion existing in the reference zone.