Was thinking about getting Bilstein leveling shocks for a 2" lift and trying to fit BFG 35x12.5R18's KM2's on the OEM 18" rims... Even found a thread https://www.f150online.com/forums/20...ndow-tint.html where someone had done this and I really like the way it looked.

But then I started to have doubts... I found posts saying the OEM 18's are 7.5" wide and BFG recommends 8" min and that the 35"s would ballon on the 7.5" OEM rims and wear down in the center... Also heard some people saying the 35"s would rub at full turn.

Then I found posts where people were saying the OEM FX4 18" rims are 8" wide??? Looked and looked and never could find the offical number anywhere. I'm pretty sure the OEM 18" wheels are 7.5" wide.

My question is, if I go with the Bilstein leveling shocks, what is the largest tire I can fit that will be within specs and not rub with an aggressive mud tread close to the BFG KM2?

 

You've pretty much answered your own questions. The OEM wheels are 7.5 inches wide with 5.5 inches of BS. You can fit 35x12.50's, but you may have some minor rubbing on the control arms at full steering lock. Yes, most manufacturers recommend an 8 to 10 inch wide wheel for 12.50 inch wide tires, but hundreds of members here and FTW have run 12.50 inch wide tires with no problems at all on their OEM 7.5 inch wide wheels since 1997.