Yes and no. The data was recorded with the old 382 and stock tires. Tires went on right after I sold that boat.

7.3 psd 4.10 gears, 13-15 all the time loaded or not.

99 K3500, monster built 454, 4-6 mpg . It would tow like hell and smoke all 6 tires, then run out of gas. That was brutal to tow with 130-150 miles was an average comfortable fuel range with a 38 gallon tank.

Recently sold 06 3500 cab and chassis, steel flatbed. 4.10's stock wheels and tires. after tuning with efi live about 10.5-10.8 unloaded, 8 towing "OLD SCHOOL" from Craig's house in Maryland to Kevin's in ct.

03 Ram CTD 5.9 dually w/ 3.73 gears, 235/80R17 tires, 6 spd manual, 50hp DDP nozzles, bully dog programmer, AFE intake and exhaust.

Have 10' 4k lb arctic fox camper on it all the time... gets hand calculated 10-11 towing 5k enclosed trailer or 7k boat. doesn't seem to matter whether the highway is flat or pulling a pass or 2.

Good stuff. Keep the honest info coming guys!

Should post my info too.

1997 K3500 454 4x4. 4.10's, stock with a tune. Empty hwy around 12. City/hwy, 9-10. Towing 38 Fountain, 7-8.

Why read 02's after the cat , unless seeing if the cat's working correctly ?

My vote: put them before the cat. That is where your true A/F ratio will be found.

Edit: Lol. I thought I was in that 496 tuning / fuel mileage thread. Oh well, most of those people are in this thread too.

What engine?

2011 f-450 6.7 PSD with 4:30 gear. 12 MPG empty. About 7 or 8 MPG towing. Mpg doesn't change much if I'm towing an empty 29' enclosed trailer or if I'm towing the 38' donzi ZX. I usually run 72 mph. It went as low as 5 mpg when I had a 35mph headwind.

08' Chevy 3500 dually duramax all stock with 140k gets 13.8 empty or loaded! I pulled a 90' TG from SC to TX and the on dash mileage never changed?

Doh! That would help lol, 6.0 gas. Wasn't a powerhouse but it did fine. Towed a 42 fountain trip 525's from competition marine in Missouri to New Hampshire with a 6.0 also. A little hard on the driveline through the mountains but not bad.