Depending on which expert you talk to, your tires should be set at the reccommended pressure on the dealer vin# label on the side of your trailer OR to the max pressure as stated on the side of the tire. Both should be set when the tires are cold (Before Towing). I use the Heartlands recommended pressure but there are others that use the Tire Manufacturers pressure. It's a matter of choice. One thing for sure is to visually check your tires for bubbles and tread separation as often as possible while traveling. Also check for an abnomally hot tire. This is usually an indication of a problem.