I initially mounted our spare on the rear bumper. Bought what I thought was a fairly heavy duty mount and set out from Arizona on a cross country trip. Made it as far as Maine before it completely failed with the steel bracket fracturing when we hit one too many potholes.
IMHO: Most bumpers found on smaller motorhomes are woefully under engineered for carrying the weight of a spare, multiple bikes and the ever popular generator mount.
Apparently there is just too much weight and movement in a vertically mounted spare much like an overloaded bike rack that a structural failure is inevitable. Fortunately I heard it break and was able to remove the tire and bracket without any issues {the spare lived in the overhead of the cabover until we got to the Nexus factory in Elkhart where I had them install the under the coach custom mount}.
The weight is down low and though you do have to crawl under a couple of feet to loosen the bolt that secures the spare it has served us well. About every third time I have the other tires checked/set for the appropriate psi at Discount Tire I ask them to check the spare as well but I always bump up the tip for having them crawl under.
:C
