| 摘要 |
PURPOSE:To minimally restrain deformation strain of the upper end of a folded part by determining the relations among the height measured from the bead base part to the upper end of the folded part, the defined height from the bead base part and the thickness of a rubber of the folded part, to be within the specified range. CONSTITUTION:A carcass ply 1 is folded at the part around a bead core 5. The reinforced layer 5 of a steel cord is disposed adjacently to the external side of the folded part 2 of the ply 1, surrounding the whole of the bead core 5. The ratio (t)/(h) of the height (h) from the bead base part with respect to the thickness (t) of the rubber disposed between the body of the ply 1 and the folded part 2 is gradually reduced in the direction of the side wall part of the tyre, and when the ratio (h)/(h0) of the height (h) with respect to the height (h0) up to the upper end 2a of the folded part 2 exceeds 0.5 or 0.8 and is less than 1.0, the value of (t)/(h) shall be within the range between 0.1 and 0.25. The value (h0) shall be within the range between 55mm. and 80mm.. If the value exceeds 80mm., a stress may be concentrated and if the value is less than 55mm., the ply may be separated. |
