Pneumatic tire including kerfs

A pneumatic tire for a passenger car having a plurality of grooves on a tread surface thereof, said grooves being main grooves extending in a tire circumferential direction and a plurality of transverse grooves extending in a tire width-wise direction, land portions formed by said grooves, said main grooves and said transverse grooves being so arranged as to define said land portions as being blocks, and kerfs disposed on said land portions such that each kerf has at least one end open to one of said grooves, wherein

• at least one stage of a step portion is disposed on at least one of the groove walls of said grooves,
• a plurality of kerfs are disposed on said step portion with smaller gaps therebetween than gaps between said kerfs disposed on said land portions,
• said kerfs disposed on said land portions comprise kerfs disposed on blocks in a tread center portion, the kerfs disposed on the blocks in the tread center portion extending in the tire width-wise direction and having both ends opening to said main grooves, said step portion being disposed on at least one wall of one of said main grooves, and the kerfs disposed on said step portion and the kerfs disposed on said blocks in the tread center portion extending in the same direction,
• one of said main grooves is disposed zigzag at the tread center portion, said transverse grooves are so arranged as to cross slantingly said zigzag main groove in the tire widthwise direction,
• said kerfs disposed on said blocks in the tread center portion and extending in the tire width-wise direction are allowed to communicate with said transverse grooves,
• at least one stage of a step portion is formed on at least one of the groove walls of said transverse grooves, and
• a plurality of kerfs extending in the same direction as said kerfs on said blocks in the tread center portion are disposed on said step portion on said at least one of the groove walls of said transverse grooves with smaller gaps therebetween than gaps between said kerfs on said blocks in the tread center portion.

A pneumatic tire for a passenger car having a plurality of grooves on a tread surface thereof, said grooves being main grooves extending in a tire circumferential direction and a plurality of transverse grooves extending in a tire width-wise direction, land portions formed by said grooves, said main grooves and said transverse grooves being so arranged as to define said land portions as being blocks, and kerfs disposed on said land portions such that each kerf has at least one end open to one of said grooves, wherein

• at least one stage of a step portion is disposed on at least one of the groove walls of said grooves,
• a plurality of kerfs are disposed on said step portion with smaller gaps therebetween than gaps between said kerfs disposed on said land portions,
• said kerfs disposed on said land portions comprise kerfs disposed on blocks in a tread center portion, the kerfs disposed on the blocks in the tread center portion extending in the tire width-wise direction and having both ends opening to said main grooves, said step portion being disposed on at least one wall of one of said main grooves, and the kerfs disposed on said step portion and the kerfs disposed on said blocks in the tread center portion extending in the same direction,
• a plurality of kerfs extending in the tire circumferential direction and opening to said transverse grooves at at least one of the ends thereof are disposed on blocks at shoulder portions which are external said main grooves, at least one stage of a step portion is formed on at least one of the groove walls of said transverse grooves, and
• a plurality of kerfs extending in the same direction as said kerfs disposed on said blocks at said shoulder portions are disposed on said step portion on said at least one of the groove walls of said transverse grooves with smaller gaps therebetween than gaps between said kerfs on said blocks at said shoulder portions.