If he drops the gears down it will help his milage but he's still going to lose some. Before I did any mods to my engine I was getting an avrage of 10 to 12 mpg on my excursion with 6" lift and 35" tires. I did find out that my milage went up a mile or two when I went to 20" rims but it also hurt the braking distance at the same time. The best I have gotten on the hwy now is 14mph and it was on the interstate and I had a tail wind most of the way. The mods on my truck are a whipple charger, shorty headers, 4" exhaust, hypertech tunner, twin electric fans, home made cold air kit. The worst I have gotten has been about 6

 

Thanx for the replys

Texas psycho, Do u have a gas or diesel excursion// My excursion has the diesel and it gets like 14 mpg around town and about 20 mpg on the highway// I do have a performance chip though

 

It better have a gas with the milage I'm getting, j/k. It has the V10. I drive my company truck just about every where and only put about 5000 a year on my excursion so I couldn't justify the extra cost of the diesel. If it was an everyday driver I would have went with the diesel in a heart beat, way better milage, more life and better resale. I kept my last truck about 15 years and plan on doing the same with this one.

 

With 33x12.5 tires on a 4x4 F250 SC, my V10 gets 11-12 around town and 14 on the highway. It's an auto with the 3.73 gears.