I have a 2003 f-250 s/d 7.3 ltr. 4x4, it is lifted 4" with 20 " pro comp tires and an auto tranny. I am getting between 10 and 11 mpg. whether pulling my 26 ft. trailer or just driving around town. I was told that is not good mpg. Does any one have any idea what I can do to improve the fuel economy or is 10 mpg normal. The rest of the truck is stock. Thank you in advance for your assistance. Bob

 

Are you hand calculatin your mileage or going by the lie a meter. But the most simple method is to go back to stock tires.

 

M relying on the lie meter. If i go back do I have to lower the truck, or will it be worth going to 18" rims? The rims on the truck were $2000, they were on the truck when I bought it.

 

The first thing I would do is hand calculate a couple of tanks of fuel. Then, you can go about doing something about it, based on a baseline... The tires are going to be a biggie, my 33" tires on 20s dropped my mileage by 3 mpg. But, they look so bitchin' that it's worth it to me!
You can go to 18s or 16s with stock size tires without changing the lift of course. It may look goofy that way, but are you going for mileage or ? Stock height would probably help, too, for less wind resistance.

 

Have you changed the odometer gear ratio to match the tires?
You may not be getting accurate mileage readings.

 

Are the 20" wheels wrapped in 35's or 37's? If 35's your OD is probably off 10%. With 37's it is closer to 14%. Lifted 7.3's with a lift like yours, running an auto tranny and no custom tuning is going to get from 10 towing to 16 on the open road mpgs. 12-14 Should be average.

I have modded many 7.3's for mileage, custom tunes is a must if you are looking for more mpgs.

 

When I purchased the truck I was told that the truck would be traveling approx. 5 miles faster than the odometer showed..That would make a diff. Tx. Bob

 

I would imagine the smaller rims and tires would also make a big difference in the turning radius as well as the mileage. I m not sure I want to do that at the expense of the looks, but, maybe so. Thanks so much for your input. Bob

 

M running 35's pro comp, maybe 33's might help. Love the looks with the big tires. Thanks, Bob

 

Truck Repair White City, OR - Wolf Performance, Inc.

Randy Wolf, Wolf Performance for your local diesel shop. This guy really knows is stuff, especially the Powerstroke. He took care of me and all my friends when I lived in Medford.

 

Hey thanks a lot RAIN DESERT, I will try Wolf, he is just down the road on 62 across from the Dom. Bob

 

Ya gotta calculate for the change in tire size fer sure. my 38's are 20% bigger circumference than stock thus adding 20% to the calcs. my 315'S are 10%...all this adds to yer mileage and incorrect speedo reading...10% off will read 50 mph when yer really doing 55...10%. you can easily figure this nowadays because gps's have speedos...compare yer dash with the gps reading for speed and calculate accordingly