To prevent an inserted bead section from being removed by fitting one end to the center axis section of the wheel fixing section of a chuck, and bringing the other end into contact with the lug section of a wheel, inserting the bead section into the wheel while partially pressing it to a bead roller, putting the other end of an auxiliary tool on the wheel, and rotating the wheel by about one rotation.

A fitting section 1 is inserted and fitted into the hole of a pipe 6 horizontally extending from the center of a chuck base section 7, and multiple pawls 8 can be opened or closed around the chuck base section 7. The rubber plate 5 of a contact section 2 formed at the other end of an auxiliary tool fitted to the chuck base section 7 is kept in contact with the lug section 10 of a wheel 9. The contact section 2 is pressed by a bead roller 12 and arranged near the place where a bead section 13 is inserted, and the wheel 9 is rotated by about one rotation. A tire 11 is pressed by the contact section 2 and is not removed from the lug section 10 of the wheel 9 when it is separated from a bead roller 12, and the tire 11 is completely fitted to the wheel 9 via about one rotation.