Patent ID: 6986372

Claim:
A tread portion for a motor vehicle tire having a carcass including side walls, said tire carcass extending between the side walls, said tread portion having a tread surface and a plurality of peripheral grooves formed therein extending partially into said tread portion, said grooves having sides, a bottom, and an open top within said tread portion, selected ones of said groove sides having an upper section sloping inward at an angle in the order of 30° to 45° with respect to a radial plane and terminating at an upper edge of a lower section above said bottom of said groove at about 60% of the groove depth to form an upper and wider part of said groove which diminishes in width radially inward toward said bottom of said groove, at least one of said sloping upper sections of said selected groove sides having serrations formed thereon over its entire surfaces to present a traction surface of expanded area extending around the majority of the tread within the upper part of the groove, wherein the side of the lower section of the groove is inclined with respect to the radial plane at an angle smaller than the angle at which the upper section slopes.