do you have the spedo recalibrated for the bigger tires???

 

Yes! Through my Edge programmer.

 

Light right foot and aired up tires are the best bang for the buck.

 

"Light right foot and aired up tires are the best bang for the buck."

That's because they are free. That's tough to beat.

 

12 mpg towing 14,000 lb fifth wheel up to 25 Hwy not towing, but I have 4:10 gears and a Gear Venders overdrive. Have gotten 30 Mpg driving 55 Mph on flat desert. 98 Dodge 12 valve, BD valve body on tranny, BD injectors, BD throttle plate, Pulse manifold, BD exhaust brake. And a bunch of stuff I've forgotten about.
Ed

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My vote would be a gear venders over/under drive auxcillary trans, it also allows you to split gears when towing, and you can run in double overdrive.
Ed

 

How complicated is that overdrive to put in? Can it be done on a 4x4?

 

Yes they make them for 4 wheel drives here's a link. Gear Vendors Under/Overdrive, 4X4 Wheel Drive auxiliary transmissions.

 

I get 13 towing my 14k lb 38' flatbed with two vehicles on it running 75mph and 25 unloaded at 80mph on the highway. I have a 2wd 5 speed with 3.55 gears and no gear splitter. Trucks weighs right at 6000lbs when empty according to the local truck scale and I still run the baby 245 tires.

If you decide to run veg at all make sure that you do NOT run those long oil change intervals. The additive package in the oil is made for diesel that gets into the crankcase, not veggie oil. You will quickly trash an engine if you get veg in your crankcase and do not do 5k mile or less oil changes. This problem become worse in a truck that smokes as tha justs means too much fuel in the chamber.

 

I managed to boost my MPG from 19 to 22.5 with some simple changes.

1. 4 inch turbo back exhaust - $237 pieced together system exits in front of rear tires.
2. Aired up the tires to 85# in front and 65# in rear.
3. Add 1 gallon of Walmart 2 cycle oil ( $9.95 ) with every tankful.

 

That gear vendors over/under drive looks like the coolest thing ever. At first I thought it was just an additional gear for over drive, but it's an additional gear that automatically shifts between every gear and an overdrive. It seems to be built as tough as can be with guys running them on dragsters and tricked out diesel tow rigs. I'm pretty sold on the product, but the price ($3,195) is a bit out of my range. I may just tell my wife that I can improve the milage to around 30 MPG (I average 20) and that it will pay for it's self. Also that investment will mean I'm commited to my truck for another 10 years and I should get a fresh coat of paint. I wonder how she'll take it?

DieselJake, I think you may be running more 2cycle oil than yuou need to. I run it as well, but only add a quart every time I fill up. The ratio I use is 1oz of 2 cycle oil per gallon of diesel.

For best fuel economy, I recommend the 2cycle oil, higher air pressure in the tires (as listed above), straight piping the muffler/resonator ($30), BHAF, synthetic oils, a tuner box that defuels and advances timing, and keeping the boost under 5psi by only using light throttle pressure. And if your wife approves, a gear vendors under/overdrive.