New to diesel ...
 

hey guys I just purchased a 2007 dodge with the 6.7. Beautiful truck. It's got a lift and 37 inch tires on it... anyways I'm getting Edit gas milage even worse when I pull my trailer. This weekend I got 6.8-6.9 mpg's... it has an edge turner (older model)... any reason why I'm getting such bad gas milage when I have friends getting twice as much? I recently added a new fuel filter and cleaned out my air filter... any help is appreciated! Thanks in advance...

martin

You're gonna have to give us alot more info to go off of.
Things like;
Miles on the truck
Trans - auto or manual
4x4 or 4x2
Mods - stock or deleted and supporting mods
Tuner settings - HP, timing, boost, rail press etc
Lifted - how high
Towing weight
Diff ratio
Towing speed and in what gear/rpm
Towing terrain
Towing conditions - rain, wind etc
Trailer type - 5th wheel, toy hauler, TT, atv hauler or what
How do you drive - granny, soccer mom, commuter, race car
What years are your friends trucks

You've got over 50 views without any answers because you asked a question without giving any details. Answers to your original question could range from "you've got a lead foot" to "your engine is toast".

As stated more info would yield better help. Anytime you install big tires, and especially not change your axle ratio to get your mph back with your engine rpm range your mileage will suffer greatly.