Some good advice so far...(some )

First question, is how are you calculating mpg ????
if not by hand and especially if you have not changed the computer to account for the bigger tires, etc...
then there is NO WAY you are calculating miles per gallon correctly.....
the miles on your odometer would be way different from actual...

but I can "gaurnteeeee" you a sure fire way to improve mpg on ANY vehicle..... ????!!!


Change drivers !!! or at least change driving STYLE....

NOT that I care about my mpg since I bought a big honking Excursion... but IF I wanted to, I could easily get 20 % better mpg... EASILY !

Now it would take me longer to get there, and I would be passed by most, but feathering the throttle like it had a brittle egg under the accelerator, COASTING whenever I see a stopping situation coming up, removing ALL unneeded weight out of my truck, etc....

Yes, the tires,wheels, and gearing are a big drag on your mpg, but bet you go hard all the time too relatively at least....

Am NOT a enviro-freak, but if you are really concerned about mpg, drive differently !

hope this helps !