Patent ID: 7270162

Claim:
A pneumatic tire having a tread surface, blocks being defined by grooves in the tread surface, sipes extending in tread surface sections of the blocks, each of the sipes having at least one end that is positioned within the block in which it is located, wherein the sipes each have an opening in the tread surface section, and are arranged such that each of the sipes meanders from the one end to the other end thereof to form a meandrous shape, and as a depth of the sipe increases, a meander width of the sipe gradually increases from the opening to at least an 80%-worn position of the block in which it is located, wherein the sipes each have a sipe length L which is defined as a center line length between an intersection of a center line passing a center of the meander width of the meandrous shape with a first straight line and an intersection of the center line with a second straight line, the first straight line being orthogonally drawn to the center line from the one end of the sipe and the second straight line being orthogonally drawn to the center line from the other end of the sipe at an equal depth position of the sipe, the sipe length L gradually decreasing as the sipe depth increases, and wherein ratios L 80 /M 0 and M 80 /M 0 satisfy the following relationships: 0.8 ≦L 80 /M 0 ≦0.95 1.0≦ M 80 /M 0 ≦1.15 where M 0 (mm) is the opening length of the sipes, L 80 (mm) is the sipe length L at the 80%-worn position, and M 80 (mm) is the actual length of the sipes at the 80%-worn position.