Quote Originally Posted by JAFO
That is too much weight for the rear door.

Even a 30" tire is too much weight for Jeep Wrangler tailgate. When you go to a larger size you have to get a tire rack that mounts to the bumper.

The hinges sag from the weight and the tailgate won't close correctly.

I'm thinking that besides fuel economy, the weight load on the hinges is the reason that Isuzu didn't incorporate a full size spare in the rear door.
Hey Jafo, FWIW, I've got a sub box and amp in my rear door that weighs as least as much as a full size spare. It's loaded down pretty well, but it still seems to operate OK. It'll probably wear those hinges out eventually, but i'm sure that will take many years - it's been about 3-1/2 years so far and other than the door being heavier and needing more of a push to shut it, I haven't had any issues.