Hey guys,

Looking to regear my truck so I get better MPG. Currently I am running 37's but may switch it to a 40 by summer. So I was thinking 4.56's but how much would I gain as fas as mileage?? Not concered all that much about power, just need to save some $$$. Also I am running the Predator chip at 85 and have a K&N CAI with a straight piped exhaust. Let me know guys.

I found this: http://www.speedworldmotorplex.com/calc.htm

Yet if you scroll to the bottom it asks to calculate rear ratio. I dont know the overall diameter of a 40" tire... I think i'm reading it right...?

I put in 5.13's and it corrected my speedo and helped driveability (and towing) alot.... I wanted 5.38s but they dont make them, but the 5.13s worked out perfectly for the 40s

What kind of mileage are you gettin?

Its a 8.1 gasser so mileage is bad... 7 to 12. But changing from 4.10s to 5.13 helped alot. 4.10s to 4.56s isnt much of a change and might not be worth the dough

Well i have 3.73's now and im getting around 14-16. So I was hoping to get atleast 17-19....

Man that's incredible mileage turning those tires!!! Is your speedo calibrated to the tires?

Yes it is, why do you think I would be getting worse??

i was getting about 12 IIRC for the week i had 3.73's in the rear. i get about 16.8 drivng like i dont care about mileage but i can squeak 17.75 out of it. and average 17.1 plus its so much easier on the trans, engine, and drivetrain.and then towing i still get upper 15's.you would/should get better mileage than im getting with the tires you have now. maybe lxh or DINO ONE will chime in since they already have foh-tees

Interesting, well hopefully I can get these and get them installed fairly soon Im thinking around April.