With just about every vehicle having mounting point for a spare tire, most under the body but some in other places, I find it a bit surprising that the spare tires themselves aren't more of a common part along the lines of the wheels that can be mounted on the axles themselves. What I'd like to propose is a similar system for the wheels, where we have a system that allows spare tires (with their special simplified Jbeam structures) to be pulled from the common folder in much the same way, with each vehicle having a 'spare tire hub' part that allows tires of a particular lug pattern to be fitted. On most vehicles that only offer one lug pattern (like say, the Burnside special, which only allows 5-lug wheels), there would be a single 5-lug spare wheel hub. For cars with more than one lug pattern (like the '88 Pessima, which offers both 4-lug and 5-lug wheels), a drop-down folder would have to be created to hold the two hubs. The ultimate benefit of this system would be to simultaneously allow a very wide variety of spare wheel/tire sets to be fitted to every vehicle, while also reducing the number of duplicated parts that need to be created and maintained.
