[Carl n Susan]

While your wheels have a max rating of 3,750 lbs. there is no way your actual load will approach that value. You have 6K rated axles and should only to expect that amount of weight. But of course you should weigh the axles to see what your actual load is. I bet it is less than 3,000 lbs. per wheel or 6K per axles. 80 PSI will handle your load easily.