Abstract: There is provided a pneumatic tire to improve on-ice braking performance.

Abstract: A pneumatic tire having enhanced on-ice braking performance achieved by further increasing the amount of water that can be sucked up into sipes. In the pneumatic tire, blocks (26) partitioned by circumferential grooves and lateral grooves are formed in the tread. A sipe (28) is formed in a block (26), and a fine structure (32) having a height in the range of from 1/50 of the sipe width t to less than 1/10 of the sipe width t is formed on a sipe wall surface. This reduces fluid friction coefficient of water relative to the sipe wall surface to a lower level than conventional products. As a result, when water staying on ice comes into contact with the sipe wall surface, the water is more easily sucked up into the sipe. The construction increases the amount of water that can be sucked up into the sipe (28) or the removal amount of water that stays on ice etc., and this enhances braking performance (friction characteristics) on ice.

Abstract: A water spray nozzle has a body of which an inner peripheral flange is provided on the upper end thereof and a core that is installed in the body and whose outer peripheral edge section of an upper end face is made to be in contact with a lower face of the inner peripheral flange. Grooves for nozzle holes are provided in the outer peripheral edge section of the core, and the grooves are formed at predetermined intervals in the circumferential direction from the outer peripheral side of the core to an opening on the inner peripheral side.

Abstract: A pneumatic tire including a tread provided with a plurality of blocks. Tread surfaces of the blocks 18 are provided with second arcuate portions 20B, which have a center of curvature outside of the tire, at a leading edge 18f side and a trailing edge 18k side of a first arcuate portion 20A, which has a center of curvature inside of the tire. With this configuration, bending deformation of the entire block can be suppressed by delaying a timing of ground contacting at the time of contact, so that the bending deformation in a direction opposite to a rotational direction of the tire, generated in the vicinity of the trailing edge 18k right before leaving, thus suppressing heel-and-toe wear in the block.