The trailer must be towed level so that the frames and tongue of the trailer are parallel with the ground.  The best way to determine the tow ball height is when your trailer is empty. Raise your tongue jack so that the frames and tongue are parallel with the ground. While on flat level ground use a tape measure to measure from the ground to the bottom of the frame on two different points on your trailer. The first point is the rear of the trailer near the taillights and the second point is where the frame meets the tongue. Raise or lower your tongue jack so both points are the same. Go to the coupler of the trailer and measure from the ground to the top of the coupler. This will be height needed for the tow vehicle's tow ball. As long as the tongue weight is between 5% and 7% of the gross weight and load is under the trailer's carrying capacity, any drop to the trailers suspension while under load will be relative to when the trailer is empty.

TIP: Be sure to have your tongue weight between 5%-7% of your gross weight. Insufficient tongue weight may allow the frames to distort or deflect making it difficult for the frames to be parallel with the ground. Need to know how to calculate tongue weight? Click here https://www.venturetrailers.com/resource/how-can-i-calculate-my-tongue-weight/