Do not assume the people at the CAT scales know what they are doing. I went in before weighing and explained what I wanted to do. They had never weighed an TT or RV before or so they said. I had to have them come out and show them while I was on the scales what I wanted to do. I had the print out of how to weigh I got from these forums on how to do the different weights. It was the first time I had used the CAT scales and thought it very disconcerting that they claimed to know not how to weigh a RV. I assumed they knew more than I did. It was very frustrating but eventually got it done. Have even went back several times and just did the three weights.