| 摘要 |
<p>PURPOSE: A pneumatic radial tire for a truck and a bus mounted to a 15 degree-drop center rim is provided to reduce weight with controlling the excessive increase of volume of a bead unit without additionally arranging a bead unit reinforcing cord layer, to greatly improve the durability of the bead unit for cracking and separation at a turn-up end of a carcass fly and the end of the reinforcing cord layer, and to secure excellent steering stability. CONSTITUTION: In a pneumatic radial tire for a truck and a bus mounted to a 15 degree-drop center rim(21), an outer surface portion of a composite side-rubber(5) and/or an envelope surface of a bead core(4) among members constituting the bead portion of the tire has a curved-line shape concavely directed toward the outside of the tire at a region opposite to an inner curved surface of an inclined protruded unit of a flange(21F) of the rim.</p> |
