My spare right now is pretty much useless. It's still the stock tire. I will replace the tire with a 37x11.5 at some point in the future, along with relocating it to future truck bed storage. I have a neat idea for a camper shell configuration that will probably get executed late summer this year. Until then, tow trucks are my friend in the event of a flat.
I've seen a picture somewhere (I think in this forum, actually) with someone stuffing a 37 spare in the original location. It is less than an inch from the exhaust pipe, though, so it's a bit too risky for my taste.