To enable even a soft tubeless tire to be smoothly attached and removed by mounting a tire rotation assisting device in the position of a tire mounting device which is opposite to a main body via a stud, and causing a pressing piece at the end of an arm provided at the assisting device to be pressed against the tire.

To attach a tire to a wheel 5, it is fitted around the wheel 5 as its side face is pressed by a bead roller 8a attached to a moving base 7. In this case, to prevent one side of the tire 16 from being disconnected from the wheel 5 by pressing the opposite side, the side of the tire is held by the roller of a pushing device 13. However, the tire 16 pressed has its bead part on one side fitted around the wheel but the bead part on the opposite side is not easily fitted. Therefore a tire rotation assisting device 14 is attached and rotated together with the tire 16 as it is pressed by an arm 24 so that the tire 16 fitted around the wheel 5 is not disconnected from the wheel when separated from the bead roller.