I have 305's on my truck with a 3" suspension lift. Anything less than that i'm almost 100% you'll rub. Buy some 3" coil spacers, add a leafs, and new shocks. Will look great with those off road rims

 

i used to have a 01 ram sport qc with 305 mickey baja claws on stock 16'' wheels only had 2'' coil spacers on front only a tiny bit of rub with wheel cranked all the way it didnt rub wheeling it either.

 

I would think a 2 inch lift (like a spacer) might prodce minimal rubbing in certain situations. The stock tire is about 32 inches on an off road, but they barely clear. However the suspension can cycle without them touching anything.
The 305 is about an inch talller and as much wider, so things will be really tight.
Adding a 2 inch spacer will move your axle backwards about 3/4 of an inch.