| 摘要 |
PURPOSE:To obtain the proper inflation and grounded surfacer shape of a tread part in case of the internal pressure charge, by forming one or two circumferential direction grooves each of which has a wide width and a proper sectional shape, at the tread center part of a radial tire for a small-sized truck which has a large flatness ratio. CONSTITUTION:A tire 1 mounted on a standard rim J has a flatness ratio of 50-70% and is charged to an internal pressure of 3.5-7.0kg/cm<2>, and at the center part 9 between both the division points P and P which are separated on both the sides in the axial direction from the tire equator C in the distance in 0.3-0.35 of the tread width WT in an unloaded state, a circumferential direction groove 11 which has a wide width and consists of one or two straight-line-shaped grooves which extend in the circumferential direction is formed. And the groove width WG is set to 0.15-0.25 times of the tread width WT, and the depth HG is set to 0.5-0.8 times of the tread rubber thickness HT at the tread center part. The tread surface 2A sets the ratio of the radius of curvature RC/RS between the arc having the radius of curvature RC at the tread center part 9 and the arc having the radius of curvature RS at the shoulder part 10, to 1.4-2.0. |
