You won't have to worry about rubbing against your fenders: the front airdam is that big piece of black plastic underneath your front fender, pointing rearward; believe it's only function is to slightly improve aerodynamics. You'll just have to cut off a piece of about 4"x5" on each side to keep the tires from rubbing at full lock. My 315s were rubbing (but only in reverse) even after a 2.5" lift install, but some quick "plastic surgery" took care of that problem. My tires aren't anywhere close to rubbing the fenders.
I also considered just getting Spidertrax spacers and saving the money over buying new wheels. At the end of the day, however, I splurged and got the wheels I really wanted (Rugged Ridge 17"x9", flat black w/machined lip). I haven't put much effort into it yet, but I think it'll be pretty easy to sell the stock Rubi wheels & tires to somewhat offset the cost.
Anyway, let us know what you end up with!