Also called a tow ball or hitch ball, a trailer ball is the immediate connection point between your tow vehicle and trailer. In conjunction with a trailer coupler, a trailer ball allows you to turn corners and travel over bumps and dips without becoming disconnected. The coupler mounts and locks on top of the trailer ball and articulates around it. Trailer balls come in a variety of diameters, including 1 7/8″, 2″, 2 5/16″ and sometimes 3″. In general, the smaller the diameter of the trailer ball, the less capacity it has.
Choosing the Right Tow Ball
Most ball mounts will require you to purchase a trailer ball separately and you will need to select one that fits your towing setup. You will need to know the coupler size, the trailer ball hole diameter of your ball mount and the weight of your trailer.
For the coupler size, most manufacturers stamp or label the correct trailer ball size on the coupler. Make sure that your coupler and trailer ball have a solid connection before towing and that all necessary adjustments have been made.
Trailer Ball Hole
The hole in the platform of a ball mount or trailer hitch tongue is where the trailer ball bolts onto. It is important to know the diameter of this hole so that you can choose a trailer ball with a matching shank diameter. If the trailer ball shank is too small, it will shift while towing and tend to come loose. If the shank size is too small for the trailer ball hole, you may be able to use a reducer bushing to make up the difference.
The weight rating for a trailer ball will be listed as the ball capacity. This will reflect the gross trailer weight limit, not the tongue weight. You must select a trailer ball with a ball capacity that exceeds the gross weight of your trailer.