2003 cummins, what mpg should I be seeing?
 

hi everyone I know this question is asked a lot, but I can't seem to find my exact situation. though I know about diesels, this is my first time owning one. I have a 2003 Dodge ram 2500 5.9 cummins laramie 4X4. it is a 4 door, long bed, it has an airaid intake, a 4 inch straight pipe exhaust, and edge 30103 programmer and no lift but 35" cooper MT's. right now I have it set on mileage and I'm only getting 16 mpg. does this sound right? I thought I would at least see 20.

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I do not bury my foot in it either

Is that in town mileage or highway or a combination of the two?

Larger/wider tires are going to increase rolling resistance which doesn't help you out in the mileage department.

it's combined about 50/50 no load no towing
yeah I'm trying to sell the tires. will they make that much difference?

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it's also an auto. if that makes a difference

That is not too bad for a combination. Larger/wider tires will make a difference not necessarily a huge difference but a difference nonetheless. Stop and go driving just kills fuel mileage all around. Being an automatic every time you stop you still have a constant pull on the engine unlike a manual.

Those 35 inchers killed your mileage. I drive my bad ass compound truck like I just stole it. Trust me after 10 years of running 4 Wheel Parts Stores I have seen what 35 inch tires do to fuel mileage.

modify your mpg by 10% to make up for your tires. Check out the gear speed calculator for more accurate #'s

i have an 05 2500 4 door short box 4x4 its getting 14 down the e way any ideas???