I am putting a 2.5 as leveling kit on my 07 FX4 supercrew. I am planing on getting 18x8.5 Weld velocity 6 wheels. Does any one know the biggest MT tire I can fit with little to none rubbing issues?

 

If you do a search for "leveling kits" most guys have what size tire they are running. 35's are the usual, the widths vary but are usually around 12.5. Just search around for guys with the same spacer set up on 04+ models. Let us know what you decide.

 

As a general rule on the new 4x4's with a leveling kit you can run 35x12.50 tires with the OEM wheels or 33's with aftermarket wheels. In you case, I'd stick with a 325/60-18 (33x13.00) tire.