Make absolutely sure you space out the rubber tire snubbers so they make contact with the spare tire when the tailgate is closed. This will keep the tire from bouncing around and causing damage to your tailgate. You will need longer bolts for the rubber tire bumpers. Just take one out and bring it to your local hardware store. I used trimmed hockey pucks, and a buddy of mine made his spacers out of wood. I ran a 33x12.5x15 tire on a aftermarket 15x8 wheel with 3.75 backspacing for 3 years without problems until I bought a carrier.
Note: Running stock wheels or wheels with stock backspacing would require you to shorten the rubber tire bumpers. I always forget to add that without at least a 1" body lift, a 33" tire may come in contact with your rear bumper. I also spaced up the stock 3rd brakelight tower with some nuts to clear the tire. The brakelight bolts were long enough.
These days, I run a Bestop Tub Mounted Carrier with a 35" tire.