Bad fuel mileage

[JHaines]

I just purchased a 2004 3500 srw,4x4 auto, 21,000 miles. I don't believe it has done very much towing. I am getting 11. 5 to 12 mpg on the highway at 60 mph. I installed a new air filter, fuel filter, and it has 35" tires. I just sold my 99 Dodge 2500 4x4 5 sp, 193,000 miles and almost always got 18-20 mpg. Any help would be appreciated. Both trucks had 3:73 gears, and mostly run on flat roads.

 

[CBrahs]

the 35's are not going to help any. I noticed that when I first bought my truck that the mileage SUCKED but once I got that new truck feeling out of my blood and drove kind of normal things started to settle down. I was getting 9. 5 and now I am up to about 14. Also have to take into consideration that my speedo is 17% off so the avg mpg is going to be 17% better than the display is showing.

 

[Matt400]

I would be curious to know what gear ratio you have, if you run in the mountains or flats and what average speeds and RPM's you see?

For starters I would go to the dealer, tell them you have bad mileage and ask them to please do this TSB:

http://dodgeram.info/tsb/2004/18-037-04.htm