A retainer assembly for use with expandable tires wherein a pair of circular metallic bands having a plurality of tabs extending radially outward therefrom are positioned around the wheel rims such that the tabs are located nearly adjacent the tire beads. A hollow spreader bar is positioned between the bands at each tab location and a headed stud is passed through the tab inwardly into the spreader bar to maintain the tabs in spread condition which, in turn, holds the tire beads against the tapers or flanges of the wheel rim during the mounting process and would also operate to retain the tire on the wheel if and when an emergency ''''run-flat'''' condition existed.