Grind off the factory tack welds holding the 3 studs in place. Take one with you to the part's sto and look through their wheel studs - find three new ones with approx. the same seat & thread, but ~1.5" longer or more. Then I took several large washers & stacked them together, used a lug nut to seat the new studs. You will have to come up with a spacer to move the wheel out a bit - I just used the washers - welded them together, then tack welded the studs to make sure everything stays in place. It sounds a little ghetto-fab, but throw some black paint on & mount the spare and it looks/works fine. Only alternative I know of is to maybe mount the wheel backwards or hack/modify the carrier mount.
I dunno how well the factory carrier would support a 32"er or larger... :looney:
