Originally Posted by BassAckwards

I used to think the same thing bud but you have to add 1" when calculating because the wheel lip is not factored in the width. That is measured from bead to bead. And of course backspacing is measured from the lip. Each lip being .5" which is why there backspacing measurements seem to be .5" off. A -12mm offset 9" wide wheel has a 4.56 backspacing.

It's dumb that they do it that way but that's how they made it. I was working in Tire Retail for a year thinking it worked the same way as you before I found out differently.

Originally Posted by F-150_GIRL

my truck already had a leveling kit on it when i bought it. im guessing its a 1.5 or 2 inch. It shouldnt be to close to the UCA should it? because the tires that came on it are very close to the UCA?so maybe just a little trimming? i just want something that will give it a little more aggressive look.

Originally Posted by BassAckwards

No the UCA won't be a problem due to the offset of the wheels you want. The fender is the only thing you'll have to worry about particularly the rear fender while driving in reverse most likely.