Unfortunately, I have to disagree with you Jason on the 7" rims for the 31 X 10.50's.
Running Goodyear Wrangler MT/R 31 X 10.50's, I am using 8" rims, as recommended by the manufacturer, and have never lost a bead.
I'm using 2-3/4" backspaced wheels.  In this case, LESS is BETTER.  Well, "just like factory" is better, I guess.  The factory 5.5" rims have about 2-3/4" of backspacing, so what that means is that all the extra rim width goes to the OUTSIDE - no more of the rim sticks INTO the wheel well.
I got my wheels from Spidertrax - but that's because there was no shipping for me - I live close enough to drive up there, and get them.  For most people if you look around, you can find the wheels you need locally.  Shipping would probably double the cost!  Steel wheels are big, and heavy!
Here's the link to their wheels, though, so you get an idea of size and cost:
http://www.spidertrax.com/drivetrain_whl.htm