This means nothing other than what I have been doing . So far, towing, 55 psi, unloaded. 45 yo 50 psi. I have been looking for a michlin chart on these specifil tires but have found nothing. I have herd to infliate them from people anywhere from door jam number which is 36 psi give or take to 80 psi. no straight answer yet so I keep it at 50.