Patent ID: 7631675

Claim:
A pneumatic tire with a designated fitting direction relative to a vehicle, wherein four main grooves extending in a circumferential direction of the tire are provided on a tread portion, the tread portion having an inner side and an outer side when the tire is mounted on the vehicle, two grooves out of these main grooves are located on each of both sides of a tire equator, five lines of land portions are defined by the main grooves, a center land portion located on the tire equator is a rib which continuously extends in the circumferential direction of the tire without being sectioned, a plurality of arcuate grooves each extending in an arc shape are provided on each of a pair of second land portions located respectively on both sides of the center land portion, an end of each of the arcuate grooves on the second land portion located on the inner side of the tread portion is connected to the innermost main groove on the inner side of the tread portion while another end of the arcuate groove is connected to the adjacent arcuate groove, an end of each of the arcuate grooves on the second land portion located on the outer side of the tread portion is connected to the main groove between the center land portion and the second land portion located on the outer side of the tread portion while another end of the arcuate groove is connected to the adjacent arcuate groove, a repeat pitch Po of the arcuate grooves on the second land portion located on an outer side of the tread portion is set greater than a repeat pitch Pi of the arcuate grooves on the second land portion located on the inner side of the tread portion, and a proportion Po/Pi of the pitches is set in a range of from 1.5 to 3.0, wherein a plurality of lug grooves extending in a width direction of the tire are provided on each of a pair of shoulder land portions located respectively in shoulder regions of the tread portion.