| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for a high-speed and heavy load in which a bead portion has sufficient durability at high-speed running under a 200% load. SOLUTION: A bead portion 1 has an apex rubber 5 and a bead reinforcing rubber strip, in which a ratio of the apex rubber M100A with respect to the reinforcing rubber strip M100R is 1.0 to 7.5. On a section of an assembly of a tire and a rim filled with a specified pneumatic pressure, a section area Ra of the reinforcing rubber strip in a region surrounded by a straight line L that passes a centroid of a section of a bead core 3 and is in parallel with a tire axial line, and a normal line N on the tire inner face that passes an intersection point P where a tire outer surface intersects with a straight line T that is in parallel with the straight line L and passes a point that is 1.5 times the height of a rim flange, is 1.5 to 3.5 times larger than a section area Aa of the apex rubber in the same region.</p> |
