I have a 97 f150 2wd with a 4.2 v6 automatic and 3.55 LS rear gears. I also have 20 inch wheels with 275/55/20 tires on them which are 31.9 inches tall. My original tire size was 255/70/16 which is a 30.05 inches tall tire. I was wondering if going to a 3.73 LS or even a 4.10 LS would help my gas mileage or would it hurt it. I do mostly in town driving with the occasional jump on the highway to go places. Any help would be greatly appreciated.

 

You probably won't notice much with 3.73's. I would opt for the 4.10's, only because that is what I'm doing. I'm not changing the stock tire size, just the ratio, going from 3.73's to 4.10's. I do mostly city driving as well. Hope this helps.

 

yes doing a swap to 4.10 will help your city MPG, maybe 1-2 MPG if you are lucky and stay off the go pedal maybe more than that, good luck