Quote Originally Posted by dieseldummy
WOW!! I just read through this thread to catch up and find myself wondering what turbo selection has to do with a gear swap for MPG??? Unless one has an interest beyond MPG.

On my '93 I started out with stock 245/75/r16 tires and 4:10 gears. That would net a consistent 15MPG around town. When I swaped to 285/75/r16's I gained nothing... probably lost 1mpg truth be known. I always atributed it to added rolling resistance. I've always been under the impression that swaping out gears doesn't have that effect because rolling resistance is the same and the only difference is how long it takes to get rolling. That's what I got out of this thread thus far, am I somewhat correct?
I think as Ronniejoe said the subject drifted a little but did cover a lot of interrelated issues.

I don't think any of the above topics concluded that a gear reduction has an adverse effect on mileage. I think yours is the only one that has stated that reducing the gearing from 4.10 to 3.73 via. tire change adversely effected mileage. I think DaBigOne's poorer mileage may be because he's reduced a little too far and was using an aggressive tread pattern. Tread pattern has a big effect as does the width of the tire. If you go bigger, any benefits may be negated if you use a really wide tire and/or aggressive tread pattern.

I believe comparing stock trucks to stock trucks it's been proven that 3.42's get better mileage than 3.73