Check out bagged_expo's build, I believe he was planning on running 37's. I'd recommend at least 4.56's for 37's to still have some power. I ran 5.13's on my dodge with 44x21's and it had a little get up.
I have 37's haven't got my truck back so don't know how it runs with them on. I have 3:73 and running 93 SCT tune. Hoping to be driving it this month. Have another buddy running 37's stock ecoboost with 3:55. It still moves, his gas mileage is about 15 around town 17 on hwy.He is getting a programmer soon so the mileage will get a little better.
Alright thanks guys. I have 3.55s on mine so I know I would need a regear sometime. Just wondering how y'all are feeling it now. I had 37s and 3.73s in my jeep it wasn't to bad. But I just don't know how 3.55s will do.
Something's going to give with that big of a tire and such a small gear! Ether pay for a new tranny down the road or pay for gears now! Ether way money will be coming out of your pocket! Just my opinion but something I personally learned the hard way!