PURPOSE: To improve holding property of a tire having low inner pressure against a rim by forming hamps neighboring the flat bead seat faces and having a prescribed diameter in one body on the outside of a wheel rim provided with a well, bead seat faces, and rim flanges.

CONSTITUTION: On the outside 1 of a wheel rim provided with a well 2, beam seat faces 3, and rim flanges 4, the rim flange 4 is connected to the flat bead seat face 3 having inclination of 5° on a base point 5 existing at diameter D. A hump 6 which is extended at least on the major part of the circumference, is provided neighboring to the bead seat face 3 and connected to the well 2. In this case, the diameter DH of the hump is instituted larger than the diameter D of the bead seat face 3 measured at the base point 5. Further, ramp faces 7, 8 are formed to begin from the well side, incline with steep angle and then with gentle angle, and connect with the hump 6.