As I believe most are, my 13' 1988 Scamp
came stock with 13" wheels. The spare tire was mounted directly to the shell via two long bolts that are embedded into the fiberglass.
When I upgraded my axle
to accommodate brakes
and 15" wheels, I was left with a few issues to resolve. The position of the original 13" spare tire carrier bolts do not fit the lug nut hole pattern of the new 15" wheels. Plus, the new wheel/tire combo were significantly heavier than the original set-up. I needed to design a custom tire carrier.
Instead of yanking the original 13" spare tire carrier bolts out and risking damage to the shell or requiring patches to the holes, I chose to use these as a "third" anchoring point for a new custom bumper. (I chose tubular steel to match the style of bumpers on my vintage Bronco). With the new bumper anchored to the frame rails AND to the shell bolts I now have a solid tire mount that carries the weight
of the spare on the bumper rather than the original shell bolts.
Here's a few pix. (You can check out my new LED tail lights