Abstract: A heavy duty pneumatic radial tire having sub grooves provided on a tread surface which has a center main groove and two outer main grooves. The sub grooves extend in the tire width direction and together with the main grooves, divisionally form two block rows composed of a plurality of blocks. The sub grooves are inclined in a direction opposite to the tire rotating direction from the center main groove toward the outer main grooves. The inclination angle of the sub grooves is gradually and continuously reduced from a first inclination angle measured at the center main groove to a second inclination angle measured at the outer main groove. The first inclination angle is set in the range from 70 to 90.degree. while the second inclination angle is set in the range of greater than 30.degree. and less than the first inclination angle. Further, notched grooves can be provided dividing the shoulder areas of the tread surface into a plurality of blocks.

Abstract: A pneumatic tire comprises an improved tread portion provided with blocks, each block provided with a sipe, the sipe extending across the block to have a first open end and a second open end, the sipe comprising three components forming a generally Z-shaped configuration, whereby the two parts divided by the sipe are engaged with each other to increase the block rigidity.

Abstract: A pneumatic tire having a block type tread pattern improved in stone trapping, which comprises the tread portion provided with a mesh of grooves to define blocks, each block surrounded by at least one projection standing out from the groove bottom leaving spaces from the groove walls, the projection comprising alternate wide main portions and narrow coupler portions, the height of the wide main portions being in the range of from 10 to 25% of the groove depth, the height of the narrow coupler portions being not less than 5% but less than 10% of the groove depth, the length of each of the wide main portions being in the range of from 3 mm to 10 mm, the length of each of the narrow coupler portions being in the range of from 2 mm to 5 mm, and the width of the narrow coupler portions being in the range of from 1 mm to 2 mm.

Abstract: A studless tire comprises tread blocks having a narrow-width center portion, a heel-side increasing-width portion and a toe-side increasing-width portion, wherein the axial width of the block becomes minimum in the narrow-width portion and increases toward the heel edge and toe edge in the heel-side and toe-side increasing-width portions, and the minimum width in the narrow-width portion being in the range of from 0.5 to 0.9 times the average of the maximum width in the heel-side increasing-width portion and the maximum width in the toe-side increasing-width portion, whereby the stress produced in the block rubber when a braking force or driving force acts thereon increases the apparent block rigidity to decrease the block edge lifting and thereby uneven wear can be decreased.

Abstract: A tread configuration for a vehicle tire, including at least two adjacent circumferentially oriented rows of profiled blocks. The rows are separated from one another by respective circumferential grooves. The base of each groove extends parallel to the circumferential direction. A respective side wall on each side of the base extends radially outwardly from the base and forms side walls of profiled blocks of an adjacent one of the rows of blocks. Radially outer end portions of the side walls of the grooves are essentially oriented in the circumferential direction and have their contour divided by a plurality of axially oriented offsets.

Abstract: A pneumatic tire for a passenger car wherein a plurality of grooves are disposed on a tread surface to define and form land portions, and kerfs which are open to the grooves at at least one of the ends thereof are disposed on the land portions. At least one stage of step portion is disposed in a step shape on at least one of the groove walls of the grooves, and a plurality of kerfs are disposed on the step portion with smaller gaps than those of the kerfs disposed on the land portions.

Abstract: A pneumatic tire comprises sipes in each land portion defined by wide-width grooves in a tread portion, in which a sipe corresponding to at least a part of these sipes comprises a pair of main portions slightly shifting to each other in the axial direction and a link portion connecting opposed end portions of these main portions to each other, and the pair of the main portions are inclined in opposite directions with respect to a radial direction so as to make a mutual distance L between the main portions large.