Abstract: A pneumatic tire includes a first circumferential groove extending in a circumferential direction of the pneumatic tire, a second circumferential groove extending in the circumferential direction of the pneumatic tire, a third circumferential groove extending in the circumferential direction of the pneumatic tire; and a fourth circumferential groove extending in the circumferential direction of the pneumatic tire, the first, second, third, and fourth circumferential grooves defining first, second, third, fourth, and fifth ribs. Each of the ribs includes lateral grooves and lateral sipes. The lateral grooves of the first rib each having chamfers on an upper side at an intersection with the first circumferential groove.

Abstract: The present invention is directed to a pneumatic tire comprising a tread, the tread comprising a rubber composition comprising from 20 to 90 parts by weight per 100 parts by weight of rubber (phr) of solution polymerized styrene-butadiene rubber, from 10 to 80 phr of polybutadiene rubber, wherein from 0 to 20 weight percent of the polybutadiene rubber is a syndiotactic polybutadiene rubber comprising at least 70 percent of monomeric units in syndiotactic 1,2 configuration and the balance of the polybutadiene rubber comprises at least 90 percent of monomeric units in cis-1,4 configuration; and from 50 to 150 phr of pre-hydrophobated precipitated silica wherein the pre-hydrophobated precipitated silica is hydrophobated prior to its addition to the rubber composition by treatment with at least one silane selected from the group consisting of alkylsilanes, alkoxysilanes, organoalkoxysilyl polysulfides and organomercaptoalkoxysilanes.