All right, I finally got around to getting pictures up.
Don't they look a little flat? And the boat is completely empty in these pictures, although a little bow down in the driveway (which should REDUCE the weight on the tires since some is on the jackstand.) Each of these tires is over 50 psi (I'm not sure how much over 50, because that's as high as my little tire gauge goes, but I've never put air into them.) They are class "C" tires and they say on the side "Maximum weight of 1760 per tire at 50 psi." So after much research on the internet, I believe 50 is the not only the maximum tire pressure, but the correct tire pressure for a class C tire. There are class D tires (70 psi) and class E tires (90 psi) but these are class C.
I still think they look flat though.