The butt dyno thought it was worth it...

 

in addition to Dodge offering
3.21 diff gears this model year
in a Ram with better
aero, lower rolling resistance tires,
and 400+ ft-lbs from the Hemi 5.7 variable valve V8,
what are competing automakers doing?

read here:

https://dodgeforum.com/forum/off-brand-news-concepts-and-rumors/172908-small-tweaks-boost-mpg-say-automakers.html

 

my 3.55 with a stickshift gets me 16 in the city, 18 on the highway. tho its hard to tell average mileage if im on it tho whole time, cuz i got the 35 gal. tank, so my mileage rating is outta like 500-600 miles. but id have to guess if im on it half the time as driving normally, im prolly more like 14.5 city, and 16.5 highway

 

So as for a truck with over 200k miles,having to already rebuild diff,thought i would put steeper gears. Only 2wd with the 5.9 so probably has 3.55. would 4.10 be too much or should 3.90 be better. Tires are going to be 275's on 16" factory wheels

 

I have 285/75/16's with 3:50.1 gears and I turn 2000 at 78mph so 4:56.1 is in my favor come tax time. Get the engine around 2300-2500rpm at your cruising speed and you will get the best milage possible.