I run 4.88's in a D44. With a manual I run 2600-2700 rpm at 65 mph. The auto has a deeper overdrive so the RPMs will be slightly lower. You will be thankful for the lower gearing when climbing hills.If its your daily driver though, you might wanna do like 4.56. When i do highway, i wish i had 4.56's for lower rpms and i have 35's.
I run 35's. I started with 33's and didn't feel much of a difference when I went to the 35's.Bryan what size tires do you have.
I was talking with Jason at WFO Concepts in Auburn and he said that he put 4.88's in when his customers will be running 33's and a auto transmission. Jason said he has done over fifty this way and everyone likes the way their rigs runs on the trail and hwy.
This is the way I will be going I think too.