22.5 put on a month ago. Prior statement with stock 17" tires. Now that the 22.5 are on, 70 mph rpm are 1500 compared to 17" stock at 1800 rpm. Recalibrated speedometer w/ bully dog for tire size. Speedometer matches gps speed within 1 mph @ 70.

 

I plan on taking my 08 back to the dealer next week. It has about 8k miles on it. Best mileage I have ever gotten on it (hand calculated) is 14.7 on the highway and that is not driving over 75. On a recent trip back from Austin, I filled up, set the cruise on 60 (got passed by everyone in everything you can imagine). Got to the outskirts of Houston and filled up again. 13.8 MPG is all it got. Something is definitely wrong with this truck and its MPG. I understand it is not ever going to get great fuel economy but this is pretty bad.

 

I think your right, that's as bad as the 6.4L Ferd I got stuck with for a couple months, one month I had a $1200 fuel bill. I'm really feeling for you guys and I wish Marco would release this bad-**** Smarty that's supposed to work wonders for you 6.7L guys! I'll keep my fingers crossed for you.

 

I wound up with 16.8 for my first hand calc fill of just over 21 gallons to top off. I'm taking a 37' fifth wheel from FL to WA next week and will have some good towing mpg #s at 60mph when I get back.

 

Hey guys, kinda new here, actually I believe this is my first post. The Dodge I have now is my second, 03 3500 4x4 QC SRW shortbox auto. It has been good to me , but...I am HATING the auto. I got a dealer in South Carolina down to 34,465 for a 08 QC DRW 4x4 6spd man. but after reading posts on fuel econ. or lack there of...I am now wondering if I should pass. Does not sound like the manual trans is any better ( it seemed to be in the past) Is the 2500 any better w/ similair set up?

 

The auto in the 03 and in the 08 are VERY different.No way would I want a manual unit in a 08.