Here's update on my attempt to bore out the Chevy rally wheels that I picked up. Unfortunately, I didn't pay attention to the fact that the rally wheels were hub- centric, rather than lug-centric, so in the end I decided not to attempt to modify them since they wouldn't have any way to center themselves on the hub unless I could get the center incredibly precise.

So now I'm back to looking for another set of wheels. Here's the question: I can pick up a set of 15x12 wheels for super cheap but are they too wide to run 12.5" wide tires? My understanding is that 12" is too wide to hold the bead. I don't do too much airing down but I'd hate to lose a bead on one of my trips to the beach.
Also, I have the choice of putting my 31x12.5s on it or my 33x12.5s. I'll probably go with the 31s since I'll have less sidewall to bend and affect the bead.

Any thoughts on 12" wide wheels running 12.5s?
Thanks

Matt