I just got the Cognito 9 inch lift now am wondering if I should go with the pro comp 37 13.50 extream A/T or there 38 14.50 will they fit any one no? there going on 20x10 xd rockstar rims.

I would go with 38's. Im running Toyo's 38x15.50x20 and love them. Had 37's on my other truck and they were good.

I second the toyos.

I think you should go with the 38's. I have 37's on mine and its not even cranked all the way and I have tons of clearance. I almost think that I could stuff a 39" Irok if I never took it off the road. My next tire will be a 38" Toyo M/T.