Trailer hitch height varies to the type of vehicle it is mounted to, however, a common maximum height used by commercial truck companies is 25-inches from the ball to the ground. If the hitch is too high or short for the trailer then the ball mount can be used to compensate the distance.
There are several types of ball mounts available, which allow the height of a hitch to vary. For hitches that are too high, there are ball mounts that have a drop. Hitches that are too low can use ball mounts that have a rise in their design.