mineral co wrote:My wheels are 7" (stock) and I'm assuming the OP's probably are as well. 8" wheels with a stock offset would have the same problem (or worse!). Did you have a lesser backspacing on yours?
Best to use backspacing when talking wheels, at least in the truck world. Reason being is offset is based on where the wheel mounting surface is in relation to the center of the wheel. Which means as the wheel gets wider, even if the offset is the same, the backspacing changes.
If you take the same tire on put it on a 7" wide wheel and a 8" wide wheel that both have say 3.75" of back spacing, the tire will be moved a 1/2" farther out when it is on the 8" wide wheel than when it is on the 7" wide wheel.
So, on an NT FSJ (Wagoneer or NT Cherokee), you can fit a 12.50 wide tire with a 8" wide wheel provided it has 3.75" or less backspacing. The tire will rub in the inner fender tub if you really flex it out, but this will not hurt the tire any. And it clears the spring fine. Although a 13.50 will not fit without a 10" wide wheel. This goes for J10's as well actually. You need an 8" wide wheel in order use 12.50 wide tires otherwise they rub the rear springs.