I take any of my new to me trucks that I will tow with to a local comercial truck scale and weigh it full of fuel and me in it(the state comercial scales here in Oregon have a external LED sign visiable to see when thier closed) and write the front and rear axle weights down, I then take the race trailer with the car in it ready to go to the races and weigh how much more weieght is now on the rear axle of the truck and how much total weight it removed from the front truck axle and then decicde if it is safe or if I need to pull it off the scales and readjust the car in the trailer and reweigh it. I do wiegh the amount of weight on each axle on the trailer also, I like to see about 150 lbs more on the front trailer axle My current set up adds between(depending on how much fuel and how long I'm going to be gone racing with luggage and the at the rack snack box wieght ) 300 and 600 lbs on the rear axle on the truck and takes around 150 lbs off the front axle of the truck The current truck is aRam 3500 single wheel 4x4 crewcab long bed that weighs in at 7600 lbs or so with one tank full of fuel and me in it. I have added a tool box with a built in 47 gallon auxillary fuel tank and a camper shell since last weighing it, sounds like it is time to reweigh it again with both fuel tanks full Sorry for hijacking It pays to take the time to be safe