A support structure for a spare tire on a vehicle. A shell is attached to the vehicle and includes first and second end portions and a bottom portion extending at least partially between the first and second end portions. The shell at least partially defines a spare tire storage chamber and includes an opening providing access to the storage chamber, wherein the opening is adjacent to the first end portion. The support member is slidably positioned above the bottom portion and is movable back and forth along a movement path from a first position in which the support member is substantially disposed within the shell and a second position in which the support member is at least partially disposed outside the shell. In certain embodiments, a retention member can be fixedly attached to the shell. In further embodiments, the support member and the shell have a cooperative locking configuration.