Patent ID: 8267131

Claim:
A studless tire comprising a tread portion having tread edges and a tread width therebetween, the tread portion provided with a middle circumferential groove disposed on each side of the tire equator to have a center line located in a region between 15% and 25% of the tread width from the tire equator, at least one inner circumferential groove disposed in a crown region defined between the middle circumferential grooves, and at least one linear outer circumferential groove disposed in each of a pair of shoulder regions defined between the middle circumferential grooves and the tread edges, said crown region provided with at least two rows of circumferentially arranged crown blocks defined by crown lateral grooves, each said shoulder region provided with at least two rows of circumferentially arranged shoulder blocks defined by shoulder lateral grooves, wherein each said inner circumferential groove is a zigzag groove composed of alternate long components and short components, wherein each of the long components and two adjacent lateral grooves which are one of the crown lateral grooves axially inwardly adjacent to the long component and one of the crown lateral grooves axially outwardly adjacent to the long component, form a cross-shaped groove-intersecting portion, said middle circumferential groove is a zigzag groove composed of alternate short components and long components, wherein each of the long components and one of the axially outwardly adjacent shoulder lateral grooves, form a T-shaped groove-intersecting portion, and each of the short components and one of the axially inwardly adjacent crown lateral grooves, form a T-shaped groove-intersecting portion, said middle circumferential groove has only said T-shaped groove-intersecting portions, whereas each said inner circumferential groove has only said cross-shaped groove-intersecting portions, the crown blocks and the shoulder blocks are each provided with sipes, and the rate Gs in % of the grooved area of the shoulder regions is larger than the rate Gc in % of the grooved area of the crown region so that the difference (Gs−Gc) in value therebetween is in a range of from 3 to 7.