An assembly of a tire and a rim, wherein the internal pressure of the tire acts so as to increase a belt tension at a belt layer (30) since the internal pressure directs to the outer radial direction of the tire at an increased width part (12) and, since the horizontal portions (14a) of drawn parts (14) are prevented from being swelled toward the center of the tire by the flange parts (22) of a rim (20), the drawn parts (14) are swelled toward the center of the tire, whereby, since a reduction in belt tension can be avoided to maintain the roundness of the belt layer (30) and thus a rolling resistance can be lowered.