SIXSLUG

^^^That's what the turbo is for....

Stock size was 275/65/16, but now is taller and wider with mud tread, my dad call's em "snow tires". I run stock Michelin 285/70/17 in the summer.

Thinkin its time to clean the IAT again...I always pull better mileage after that for a while.

Without a bunch of aerodynamic mods, you should realistically expect around 20 with a mileage chip, exhaust/intake set up, tight trans, good tires and alignment and smart driving style. A lot less towing depending on how much weight in the trailer and how many axles....

rickf

That's what the turbo is for....

True but you are starting with less dense air and you have the same size turbo so you will end up with less dense air at the intake as compared to sea level. I can remember going over those mountains in the Rockies with what was at the time considered to be a monster engine, a 425 Cat, in a KW and the closer to the top the faster you were downshifting! The smoke was just a rolling. There just wasn't enough air. This was before there were computers to compensate for everything.

SIXSLUG

I hear ya! My 69 GTO was a screamer at sea level, but up in Big Bear it was a real dog, even switching jets didn't help much.

My truck seems to pull pretty good thru the passes to MT, but haven't tried with a trailer or too heavy of a load....

bentwings

The ultra low cost about 2 mpg.

With summer fuel I get 20.8 +/- .2 very consistantly.

With the max winter fuel now it is 18.8 but it can drop a lot if it is very cold or snowy.

Lots of air in the tires. cost per mile of tires is very small but fuel is a re-occuring cost and it is high.

Our bio diesel has helped the vp guys a lot I think but it also cost a mpg or so.

Best bet is 58 mph 2000 rpm. faster and mpg goes down fast. Just take your time and enjoy the drive.

Vern Hague

I have a 04 Cummins with a Fass 150 and I got 19.5 average with the cruise set to 70. I was told with the right tuner I could hit 22 or 23 so we’ll see!