I average 18.5 liftetime according to the OBC with my '03 3.0 with 5-speed manual, and 20" staggered wheels/tires, which I know cost me about 1-2 mpg because of the weight. I run 33 psi front and rear, Toyo Proxes ST II tires.

When i calculated the last fillup manually (miles driven on the obc divided by amount of gallons filled up, I reset each fillup), I was at 18 mpg even. I drive mixed, about 60% highway and 40% city driving on a tank.

In my opinion not bad for a 3 ton SAV that is 10 years old, of course if i went back to factory 17s or 18s the mileage would probably improve but I love the looks of my 20s way too much.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards