Pneumatic tire with tread surface having blocks with sipes forming meandrous shape

800 80 0 800 80 0 A pneumatic tire including sipes that have at least one ends positioned within blocks. The sipes 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 the depth of the sipes increases, the meander width of the sipes gradually increases from their openings to at least the 80%-worn position of the blocks. The sipes each have a sipe length L, which is defined as a center line length between an intersection of a center line passing the 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 the same depth position of the sipe, the sipe length L gradually decreasing as the sipe depth increases. The ratio L/Mof the sipe length Lat the 80% worn position to the opening length Mof the sipes is in the range of 0.8 to 0.95, and the ratio M/Mof the actual length Mof the sipes at the 80% worn position to the opening length Mis in the range of 1.0 to 1.15.