Patent ID: 7137424

Claim:
A winter tire containing a tread surface which is provided with a pair of rib portions having sipes and continuously extending in the tire circumferential direction, said rib portions being provided with grooves which do not completely divide the rib portions, said grooves having a width of 3 mm or less, and a central vertical groove disposed between said pair of rib portions and continuously extending on a tire equator in a tire circumferential direction, wherein side groove edge lines defined as lines in which groove wall surfaces on opposite sides of said central vertical groove intersect with a tread surface, are composed of reference pitches repeated in the tire circumferential direction, each of said reference pitches comprises a main portion including at least an inclining component which inclines with respect to the tire circumferential direction, and extending from an origin being at an outermost side in the tire axial direction to a terminal end being closest to the tire equator, and an auxiliary portion consisting of an axial direction component which extends in parallel with the tire axial direction from said terminal end to a line in the tire circumferential direction passing through said origin so that said groove edge line has a saw-tooth shape, and a length (Pa) of said reference pitch in the tire circumferential direction is larger than a pitch (L 1 ) between said sipes in the tire circumferential direction.