PURPOSE: To make a combined use for a standard tire and a large diameter tire possible by mounting a diameter increasing annular body whose diameter becomes the same as the large diameter tire freely removable to a spare tire base body wherein a tire part whose diameter is the same as the standard tire is attached to a rim wheel.
CONSTITUTION: In a car, a standard tire 3 is mounted to a rear wheel R and a large diameter tire 2 to a front wheel F respectively. In this instance, a spare tire base body 6 is formed by attaching a tire part 5 whose diameter is the same as the standard tire 3 to a rim wheel 4. And, a spare tire 1 is constituted by attaching a diameter increasing annular body 7 that forms a toroidal shape covering the tire part 5 and becomes of the same diameter as the large diameter tire 2 when attached freely removable to the spare tire base body 6. Namely, the diameter increasing annular body 7 is formed by attaching multiple increasing annular pieces 36 to the rim wheel 4 with bolts 37. Thus, a combined use of the spare tire 1 for the standard tire 3 and the large diameter tire 2 is made possible.