PURPOSE: To prevent the breakdown of a deflection quantity sensor during measurement by providing a tire lifter and a fitting sensor detecting the defective fitting of a measured tire on the fitting section at the tip of a rotary shaft, and providing the noncontact type deflection quantity sensor.

CONSTITUTION: A measured tire 10 is mounted on the guide base 23 of a lifter 3, and a switch 35 is operated to lift the tire 10 in the arrow (a) direction with the lifter 3. When the center of the tire 10 coincides with the axis of a rotary shaft 5, the laser light of a center sensor 24 is shielded by the lower end of the hub hole 25 of a wheel disk 11, thus the lifter 3 is stopped. The tire 10 is moved in the arrow (b) direction, bolts 12 of a fitting section 9 are matched with bolt holes of the disk 11, and nuts are fastened to fit the tire 10 to the fitting section 9. The disk 11 uniformly presses a disk 14 via four projections 7 if the tire 10 is not inclined, four proximity switches 15 are all turned on, and the subsequent measuring actions can be performed. If the tire 10 is inclined and any switch 15 is not turned on, no measurement can be performed unless the inclination is corrected.