anybody!! how to improve MPG on llifted truck

[jpringle83]

Did you switch tire brands and or style of tire? Different manufacturers tires have different weights. Your new 40s could weigh up to 80lbs more per tire and that extra rolling resistance as well as a different tread pattern doing the same thing. If you had it geared for the 38s the regearing it for the 40s is pointless because the tire radius is only 1" bigger.

 

[Dogman]

Have you had the dealer match the tires to the trans.? This will play a big part in bad mileage to.

 

[jpringle83]

I agree with that if it wasn't reprogrammed for the 38s.