To make speedy mounting of a tire on a rim and inflation of the tire.

A tire T is filled with air in an inflating time that obtains a mounting inflating pressure (bead-seating inflating pressure) which allows the tire T to be mounted on a rim 23 and which varies according to the type of the tire T. The mounting inflating pressure is automatically set in the tire T to mount it on a rim 23 so that beads properly seat. This prevents an inflating time from extending and requires only a short period of time for pressure regulation following the inflation. The amount of air required corresponding to the volume of the tire T, e.g. width and height of the tire, is usually known. The calculation of an air inflating time based on this value therefore requires special data, which makes the job easier.