Im running 37's with a weight of 100lbs-150lbs per tire/wheel on my D30. What I have done to mine dana 30 added an Eton Elocker and 30 spline molly shafts. Also Moog ball joints and Timken hubs. Oh and my YJ is a daily driver. Hub conversions are only good for up too 33 in tires from what i have read.