17x9 Mickey Thompson Classic Lock Rims (5.5 inch b/s) and 305/70R17 on a 2005 FX4 with 2.5" AS.....

 

It will be close, but should work.

 

Like how close are we talking. Should I be concerned with rubbing? I don't want to drop $1500 on these and have to use a football field to make a turn...

 

You'll be sticking out about 1 1/2" more than stock, you ought to be ok except doing any hard offroading. Probably nothing more than a little trimming can handle! That setup ought to look great. Goodyear and Maxxis make's the 305's in mudder's.