I have a SN 200 sitting on a Ram-Lin single axle trailer. The tires are ST225 75R, load range E, 10 ply rating, maximum load capacity 2830 lbs. (each) at 80 PSI air pressure. The shipping weight of the boat trailer is 1,040 lbs., the dry weight of the boat is 2,800 lbs. Since there are two tires splitting the weight of the boat/trailer not even considering that maybe 100 lbs of the gross weight is transferred to the trailer hitch on my truck, my tires have more than enough capacity - even considering the weight of gas and gear in the boat. I do not, however, run them at 80 PSI. I run them at 65 lbs. because the ride for the boat is a little (perhaps a lot) smoother. I have used 65 lbs. pressure since the rig was new in 2015. I am on my second set of trailer tires due solely to age, but I have never had a blowout or flat. But, should I be running 80 lbs. tire pressure? I'm guessing that tire capacity diminishes as tire pressure is reduced. If so, how much or at what ratio? What do you all think?