I bought this bike rack from another guy who had used it twice before he sold his jeep. I have mounted it up but never used it. It will fit up to a 12.5" wide tire but it will NOT fit mine with a rim with 3.75 BS. If you had 4 to 4.5 it would for sure fit the 12.5" tire. Only bad is the cable lock does not have a key, I am sure you could order a new one.
So $100 will take it OR a trade for a hitch mount rack. I plan to put on a rear bumper, maybe a hitch extension if needed and do hitch bike rack.
http://www.yakima.com/shop/bike/spare-tire/sparetime