need to make room for some meat!!

What is the size of the wheels? Back spacing?

If it hitting the outside lip, it is best to get other wheels with the proper backspacing to tuck the wheel in farther. Another thing you can do if you plan to upgrade the rear is, go with a 9" end and shorten the axle tubes/axles a little to pull the tire in. Aftermarket axles come with 3" of spline, in a spool you only need 1" of engagement and per Moser and others it is OK to cut the axle down, just need to dress up the splines to make sure they are smooth.

I have 325/50's goin on mine, 6.5" backspace 15" x 10" wheel, axles are 1" narrower, extensive modifications to the rear wells, but it will tuck the tire.