Measure the weight of the load the trailer is carrying with a weight scale, and write this number down with pencil and paper; for example, if you measure the total load as 500 lbs., write this number down.
Add the trailer's weight to the load's weight with the calculator. For example, if the trailer is 4,000 lbs. and the load is 500 lbs., this number will be 4,500 lbs. and is the weight for the back, or tandem, axle. Write down this number with the pencil and paper.
Use the tractor's weight to determine the front axle's weight to finish. For example, if the tractor weighs 6,000 lbs., then the front axle weighs 6,000 lbs. Write this number down with the pencil and paper.