It is important not to overload your trailer. You should not exceed the maximum load specified or recommended by the trailer manufacturer, nor should you exceed the tyre or coupling capacity.
Trailers now have attached to their drawbar or body a plate displaying the ATM (Aggregate Trailer Mass) which is the maximum allowable weight of the loaded trailer.
For safety and ease of towing the ball mass (the mass towards the front of the trailer carried by the tow ball of the towing vehicle), should be about 10% of the total laden trailer weight. The ball mass can be measured either at a weighbridge by resting only the jockey wheel on the scale, or by placing a ball mass scale under the coupling then taking the weight off the jockey wheel. Depending on capacity, bathroom scales can also be used.