Well, really, when you think about it - the difference between a 32 and 33 inch tire isn't going to affect things more than 3 or 4 percent.

I don't want to make the difference out to be more than it is.

 

I just talked to the guys at 4wheelparts and they can't see anything that should have caused such a drop in MPGs... except MAYBE the tires are much heavier than the others due to them being the 8 ply LT tires. I thought that might be a factor, but I did lose the 20s for 17s... I just can't think of why I lost so much so fast. Oh well... my truck looks and drives nice

 

The guy there suggested that 4:10 gears would be appropriate, but I don't think that would be much of a difference over the 3:92s that I have now.

 

How do you reset the overhead?

 

1) You are enjoying your mods (heavier foot - we all do it without realizing).

2) The tires heavier weight / wheels lighter weight should be a wash.

3) NEVER listen to ANYBODY behind the counter at ANY 4 Wheel Parts store! The kid is making .50 cents over minimum wage and was probably fired from a local McDonalds last month. 3.92s to 4.10s is an almost completely un-noticeable difference and a waste of $2000 (at 4 Wheel Parts prices).

4) do the efan next, best MPG bang for the buck...

 

1) perhaps... but it must be without realizing.
2) that's what I thought too. I'm glad you are confirming that.
3) He wasn't a kid, but otherwise you are probably right.
4) yep, it's on the list. I suppose there is a FAQ for that one too? (I'll just go look

I appreciate everyone's input.

 

The last 3 tanks calculated by hand not overhead. 11.9, 11.9 and 12.4

The first tank was normal driving with a short trip pulling the boat. The second was just normal driving. The third was me driving as cautiously as I can. I intentionally drove like an old man (no offense to old men) just to see what my best gas mileage would be.

12.4.... That's just crazy. I have always been somewhat pleased that I had to the 4.7 because I thought it was giving me better gas mileage. Now, I'm disappointed because I hear of people with the 5.7 getting better gas mileage than I am. They can tow/haul more AND get better gas mileage.

There, I cried. Thanks for listening.

 

I have a 5.7 and I do get better gas mileage than you. All I have done to mine is a Super Chip,set on High Performance and a K&N CAI. I average 13.5 around town and where I live is at about 5600 feet above sea level.
I'm no mechanic but I think that the truck is pretty heavy for the 4.7. So the motor has to work hard to pull it. The hemi doesn't have to work as hard to pull the load so it gets a ittle better gas mileage.

 

I got 12.3 mpg on the last tank. That was 87 octane Shell gas. I'm gonna do a little experiment with some of the following tanks. I just filled up with 89 octane Chevron gas. I intend to drive my normal driving habits to see what difference it makes. I realize that I can't have a perfectly controlled experiment, but over time it'll be fun to see what differences I see.

 

I recently changed out my strait exhaust for a magnaflow and lost MPGs