A tire mounting apparatus is constructed from a first working mechanism and a second working mechanism that are separate from each other. The first working mechanism is provided with a tire holding device for holding a tire and with a temporary tightening device for temporarily tightening nuts onto hub bolts to which the tire is mounted. The second working mechanism is provided with a final tightening device means for finally tightening the temporarily tightened nuts. The final tightening device includes two nut runners and an interval adjuster for adjusting an interval between the two nut runners.