| 摘要 |
PURPOSE:To provide a large block edge effect by adopting double-projection tread face wherein a circular arc with the outline of small radius passing a tread center point and a tread side edge is the contour in section, and forming a groove contiguous in the circumferential direction at the substantially central position of each outlined circular arc. CONSTITUTION:A reference circular arc 16 is so assumed that it has its center on the equatorial plane 10 of tire and passes both tread side edges. The radius of the reference circular arc 16 is set 2-3 times the maximum width W in section of tire. The crossing point between the reference circular arc 16 and the tire equatorial plane 10 is assumed to be the tread center point 18. In this case, the sectional contour of tread face is formed in a double projection shape of one outlined circular arc 20 passing one tread side edge 12 and the tread center point 18 and the other outlined circular arc 22 passing the other tread side edge 14 and the tread center point 18. At the tread face, three zigzaged main grooves 31, 32, 33 contiguous to each other in the circumferential direction of tire and auxiliary grooves crossing them, and the main grooves 31, 32, 33 on both sides are respectively positioned at the central part of the circular arcs 20, 22 substantially. |
