08 Lmm Need More Mpg, How?

zaddict · 05-05-2008, 08:58 PM

I just picked up 08' 3500 dually LMM and fuel mileage sucks, and 22.5 rims have speedo off. Is there a programmer that will set tire size and pick up mpg's?

BlackSilver · 05-05-2008, 09:37 PM

The first thing you can do to improve mileage is to lose those tall wheels.

In any case the 3500HD is not an economy car. Mine, with careful driving, averages about 18.5 on the highway, 14-15 in mixed town/highway empty. About 10-12 pulling 13,500#.

**daddysLBZ** · 05-05-2008, 09:40 PM

Mine with 285's made a 2-3 mpg diff,so I can imigane yours is a lot worse,smaller tires for sure..

zaddict · 05-06-2008, 04:13 PM

I noticed the PPE programmer says it will allow you to adjust for tire size and gain MPG
how is it? And what about the Quadzilla? Any thoughts?

Nor-Cal Nick · 05-08-2008, 09:04 AM

You can use a downloader to re set the tire size but if you are running large tires on your 22.5's I might sugest re gearing your truck.

Nor-Cal Nick

zaddict · 05-11-2008, 03:19 PM

Nick, why re gear, I realize I lost take off torque but shouldnt my cruising speed be better?
lower RPM for speed attained? Wouldnt lower RPM mean better fuel mileage?

**4x4Fantasy** · 05-11-2008, 03:22 PM

No, because those 22.5 rims are heavier, higher rotating mass, your actually hurting your MPG right now. Plus, your speedo, and miles driven, will be off as well. Get a tuner, have everything adjusted properly, and go from there.

Nor-Cal Nick · 05-11-2008, 03:36 PM

Quote:

Originally Posted by zaddict

Nick, why re gear, I realize I lost take off torque but shouldnt my cruising speed be better?
lower RPM for speed attained? Wouldnt lower RPM mean better fuel mileage?

Quote:

Originally Posted by 4x4Fantasy

No, because those 22.5 rims are heavier, higher rotating mass, your actually hurting your MPG right now. Plus, your speedo, and miles driven, will be off as well. Get a tuner, have everything adjusted properly, and go from there.

x2

It is taking more of your engine to maintain speed than saving fuel. Low rpm's don't always mean better.

lvjunior · 05-11-2008, 09:53 PM

I don't know if I agree on the tire/gear ratio thing. I have 35X12.50's on my truck with no chip and only a speedo recalibratior and see 18-18.5mpg highway and about 14.5 in town with more stop than go traffic.

after reading the other posts around here I don't seem to be doing as bad as the stock trucks

**4x4Fantasy** · 05-11-2008, 10:00 PM

There is a BIG difference from a 35x12.5 on a 17 or 18" rim as opposed to running a 22.5 STEEL rim... Its not the size of the tire thats hurting, its the weight! Rear gears are a very valuable part of a drivetrain. They can ease the stress your drivetrain sees if you want to run a larger wheel/tire combo. Add more gear if you have a heavier setup and you can actually improve performance!