Patent ID: 6343636
Filing Date: 2002-02-05
Classification: B60C,Y10S,Y10T

Abstract:
A pneumatic tire comprising:a tread portion with tread edge lines of a ground contacting portion of the tire, a pair of sidewall portions, a pair of bead portions, a carcass extending between the bead portions, a belt disposed radially outside the carcass in the tread portion, said tread portion provided with a pair of circumferential grooves disposed within a central part to define a circumferentially extending rib therebetween, the central part centered on the tire equator, said tread portion provided on each side of the tire equator with axial grooves extending axially inwardly and continuously from the tread edges to the circumferential grooves to define circumferentially spaced blocks between the axial grooves, said axial grooves inclined to the same direction with respect to the tire axial direction to form a non-directional tread pattern, wherein said axial grooves have the following designs (a) and (b), (a) the inclination angle of each of the axial grooves with respect to the tire circumferential direction being decreased from an axially outer end thereof at the tread edge to an axially inner end thereof at the circumferential groove, so as to have a minimum inclination angle of less than 45 degrees, and a maximum inclination angle of from 60 to 85 degrees, and (b) a stream angle of each of said axial groove being in the range of 10 to 40 degrees, wherein the stream angle is the angle between the tire equator and a straight line drawn between the intersecting point of the axial groove with an edge line of said central part and the intersecting point of the axial groove with the tread edge line, each said block provided with a toe edge and a heel edge along the axial grooves, both the toe and heel edge inclined to the same direction with respect to the tire axial direction so that each of the toe and heel edges has a far end and a near end, the inclination angle of a side face of each said block measured in a tire cross section parallel with the tire equatorial plane, with respect to the tire radial direction, along each of the toe and heel edges is gradually increased from the near end to the far end.