| 摘要 |
<p>The invention relates to a pneumatic radial tire which has the feature as follows : a pair of bead cores (5) ; a carcass ply which is composed of steel cords (2) being turned up around the bead core (5) from the inside toward the outside and disposed with respect to the radial direction ; a belt layer whose cords are disposed at a comparative low angle which respect to the equatorial line of the tire and a steel cord reinforcing layer (3) disposed adjacent to the outside of the turned up portion (2a) of the carcass ply, the height (ho) of the said turned up portion (2a) from the bead base portion is within a range of between 55mm to 80mm. The rubber thickness (t) which is between the carcass ply itself and its turned up portion, is at a certain height (h) from the bead base portion, (t/h) decreases gradually in inverse proportion to values of (h/ho) within the range of 0.3 </= (h/ho) </= 0.5 or 0.3 </= (h/ho) </= 0.8, and takes an approximate constant value from 0.1 to 0.25 within the range of 1.0 (h/ho) 0.5 or 1.0 (h/ho) 0.8. An application is the manufacturing of a heavy duty tire.</p> |
