Pneumatic tire having tread provided with three-dimensionally shaped sipes

A pneumatic tire whose rotational direction is specified as one direction, the pneumatic tire having a tread surface provided with a plurality of circumferential-direction grooves each extending in a tire circumferential direction, the tread surface including shoulder regions at lateral edges thereof,

• and with a plurality of lateral grooves comprising first lateral grooves, and second lateral grooves shorter than the first lateral grooves alternately formed therein, each extending in a tire widthwise direction, and being arranged in the tire circumferential direction at a predetermined pitch, the tire comprising:
• a central rib formed on a tire equatorial plane in the tread surface and demarcated by the circumferential-direction grooves, the rib being substantially continuous in a circumferential direction of the tire, and having a barbed shape, and
• a plurality of blocks formed in the shoulder regions of the tread surface and demarcated by the circumferential-direction grooves and the lateral grooves,
• the pneumatic tire is provided with three-dimensionally shaped sipes extending in the tire widthwise direction and arranged in the tire circumferential direction at predetermined intervals in the rib and
• each of blocks further includes three-dimensionally shaped sipes arranged substantially parallel to each other and also parallel to the sipes arranged in immediately adjacent blocks, wherein:
• each of said first lateral grooves extends outwardly from each of respective recesses of the rib, and continues all of the way to the outer shoulder of the tire,
• the rib is formed to have a barbed shape including a plurality of projections which alternate from side to side and which define recesses proximate the projections;
• the sipes provided in the rib are each formed in a three-dimensional shape and extend zigzaggedly in a depth direction, and the rib is configured such that an amount at which the rib collapses, when an external force in the tire circumferential direction acts on the rib, is smaller in the tire rotational direction than in a direction opposite to the tire rotational direction;
• the sipes provided in each block include sipes provided in a block tread-in side portion situated in a side of the block in the tire rotational direction, and sipes provided in a block kick-out side portion situated in a side of the block in the direction opposite to the tire rotational direction;
• the sipes in the block tread-in side portion are each formed in such a three-dimensional shape that an amount at which the block, if entirely provided with the sipes, collapses when an external force in the tire circumferential direction acts on the block will be smaller in the tire rotational direction than in the direction opposite to the tire rotational direction;
• and
• the sipes in the block kick-out side portion are each formed in such a three-dimensional shape that an amount at which the block, if entirely provided with the sipes, collapses when an external force in the tire circumferential direction acts on the block will be smaller in the direction opposite to the tire rotational direction than in the tire rotational direction.