I forgot to add, the difference between 3.92 & 4.10 is under 100rpm at any given speed. Do you honestly think that would make a noticeable difference in mileage?

On the other hand there're limitations, if you drive a lot at 80mph that's a different story. Once you go above 2300rpm or so mileage starts going down quick.

Post your tire size and driving conditions.

 

for that turd at the least 4.10s.. theres not much difference between 3.90s and 4.10s.. just go with the 4.10s... if it were me Id run 4.30s and 4.56s..

 

Im running 275/45/20 which are almost a 30" tall i think and eagle 219's which are pretty damn light for 20"s

 

If you hit the highway often I'd say 3.90, but the difference is so minimal vs 4.10 that if it was me I'd choose the later.

I've never read a thread/post of anyone complaining they went too low (higher numerical) on their gears, but it's common to hear guys regret not going with the next lower gear available, me included as I regret not getting 4.30