Re: importance for mpg gain?
tires and lift are brutal on mpg.
I know it would "look funny". But I'm curious what would happen to your MPG if you just threw on the stock wheels/tires/airdam, because I suspect the lift is what is hurting most. If it improves the MPG, perhaps running the stock wheel/tires/airdam for the 80% of time you drive on paved roads is worth doing. Then install the big wheels/tires on weekends when you go wheeling. This is what I plan to do next year. I had a hypertech programmer on my durango, I think I got 10% improvement in mpg - of course the programmer cost me $250.
the other thing to keep in mind is that with larger wheels/tires, your odometer will say you haven't driven as far (unless you've corrected the odometer), but you've used the same amount of gas as before.
2008 WK "S" Limited bright metallic silver, 5 speed W5J400 transmission, June 18/2008 build, 213RE rear differential with 3.73 axle ratio, 245/60R18 Goodyear Fortera tires, NV245 transfer case, 3.0L CRD.