Pneumatic tire with tread including circumferential rib region, block regions and sipes

Abstract

It is a subject to improve wet performances and noise performances while restricting degradations in dry performances, and for solving this subject, the pneumatic tire is comprised of a tread grounding surface that is partitioned into four to five regions by three to four main grooves that extend successively in the tire circumferential direction. The main grooves are comprised of one large width main groove which groove width comprises 4 to 20% of a tread grounding width and which is apart from the tire equator by a distance corresponding to 5 to 30% of the tread grounding width further to one grounding end side, and small width main grooves that are disposed between the large width main groove and the other grounding end and which groove width is larger than 2.0 mm but smaller than that of the large width main groove. Both groove side edges of the large width main groove extends in a successive and linear manner in the tire circumferential direction without being interrupted. A ratio ST/SY between a front and rear rigidity ST of the tread grounding surface and a lateral rigidity SY is set to be larger than 0.9 but smaller than 1.1. The lateral rigidity SYs is set to be larger than the front and rear rigidity STs for the shoulder block regionson both sides. As for the central block region (when the number of main grooves is three, crown block regions, and when the number of main grooves is four, the circumferential rib region), the lateral rigidity SYc is smaller than the front and rear rigidity STe.