I run mine at 26 to 27 psi. Will bump the back up to 30 psi hauling my camper and loaded down for Jeep traveling.Just got a set of STT Pros in 37x12.50x17 installed yesterday, coming from 315/70/17 BFG KO2's that were 'C' rated. I can say I am pleasantly surprised at the comfort and volume as well as the traction in rain. My KO2's fishtailed at every corner in the rain and I couldn't get the Coopers to slide yesterday. I was set on getting Ridge Grapplers or Toyo RT's because I didn't want the noise of a mud terrain but they are on a national backorder. It has been 20 yrs since I have had a mud terrain but the hum of the STT's is quiet in my opinion. Now just need to dial in the chalk test as the 40psi Discount set them at is sending the car all over the road.