I run 37's with stock 20's, 3.73's HO Aisin.. I gotta say, I thought i was buying a superior 37/12.5/20 tire, boy was I WRONG!!!!! I was a long time BFG customer for AT & muds. Specifically KO2 & KM2's & now the KM3's. I just got done running the 37 KM3's for about 35k miles with epic dissatisfaction! Initially when i purchased tires and installed, they could not get perfectly balanced due to OUT OF ROUND tires. I even installed balance rings and it helped but not to satisfaction. I ended up returning 3 of the set to also receive another out of round set... Super frustrating! So they balanced out a little better but still with annoying vibration, so i just ran them. Super loud on the road at end of life... Forward to today and finally swapped bfg for TOYO RT/TRAILS. What an AMAZING difference!!! These in my opinion are the best 37's to run!! Perfectly balanced from the start, extremely quiet on the road for a 37. I am having great experience with them and transmission. No searching or lugging for gears. I wish mpg was little better but it does not matter at all to me..15 city 18 hwy...