To reduce the deformation of a rim in receiving the application of external stress by providing a bead holding flange in the rim and an axial direction section having at least one U-shaped cavity extended over the full periphery of the rim in at least one bead holding flange.

A rim 2 includes a seat 11 for receiving one bead, and the seat 11 is disposed between a flange 9 and a boss 10 for holding the bead in a prescribed position. The rim 2 further includes a well 13 connected to the seat 11 by an annular rim section 12. Deformation caused by the expansion pressure of a tire is dispersed to both sides of the section 12 in a place for connecting the rim 2 and a disk 3 together. A flange 8 includes a U-shaped axial direction area extended over the full periphery of the rim such that the rim 2 constitutes a supporting body sufficient for the tire. Thus, while increasing rigidity at the level of the holding flange 8, the high degree of flexibility is maintained for the flange.