Patent ID: 7992606

Claim:
A pneumatic tire for heavy load comprising: at least three ribs extending in a circumferential direction of the tire, wherein the at least three ribs are separated from one another by means of at least two circumferential main grooves extending in the circumferential direction of the tire, the at least three ribs being formed in a tread; a circumferential fine groove extending in the circumferential direction of the tire and opening to a tread road contact surface, the groove being formed in an outermost rib of the at least three ribs, the outermost rib being on an outermost side in the tire width direction among the at least three ribs; a shoulder rib formed on an inner side in the tire width direction of the outermost rib; and a sacrificial rib formed on an outer side in the tire width direction of the outermost rib, wherein: a sacrificial rib road contact surface has an offset amount H of recess to an inner side in a radial direction of the tire with regards to a shoulder rib road contact surface that is set within a range such that 0 mm≦H≦0.5 mm; the circumferential fine groove is angled such that an opening side thereof is located on the inner side in the tire width direction of the outermost rib when filled to a proper internal pressure; and a dimension Wa in the tire width direction of the sacrificial rib road contact surface of the tire is set with regards to a dimension Ws in the tire width direction of the shoulder rib road contact surface of the tire such that 0.10≦Wa/Ws ≦0.20; a dimension Wb in the tire width direction of the road contact surface of the sacrificial rib when the groove depth of the circumferential main grooves has worn 20% with regards to the dimension Ws in the tire width direction of the shoulder rib road contact surface is set in a range such that 0.25≦Wb/Ws ≦0.30; a dimension We in the tire width direction of the sacrificial rib road contact surface when a groove depth of the circumferential main grooves has worn 40% with regards to the dimension Ws in the tire width direction of the shoulder rib road contact surface is set in a range such that 0.30≦Wc/Ws ≦0.35; and with regards to the tread road contact surface that contacts the road surface when filled to the proper internal pressure and a proper load is applied, a dimension TW in the tire width direction when the tread is spread open, a dimension TWc in the tire width direction of the road contact surface of a center rib at a center in the tire width direction, a dimension TWs in the tire width direction of the road contact surface of the outermost rib, a dimension TWh in the tire width direction of the road contact surface of the rib between a tire center in the tire width direction and a tire outermost side in the tire width direction, and a groove width GW of all of the circumferential main grooves satisfy 0.40≦TWs/(TW/2), 1.05≦TWs/TWh, 1.05≦TWs/TWc, and 0.15≦GW/TW ≦0.20.