Trucks come in a wide variety of heights, overall lengths and bed heights. The above general information about truck can aid in designing the loading dock, it is best to remember that each of the above truck heights can vary as much as 6" to 8" (12" if air-ride trailer suspension) in height from empty to fully loaded, this is know as "float". When designing the dock it is a good practice to ask the client for a list of trucks serviced at the loading dock; i.e. height, width, overall length, bed height and frequency that they arrive at the loading dock.
If a wide variety of trucks are to be serviced it may be practical to have several dock heights or one (1) dock position dedicated with a dock scissor lift or a truck leveler to accomplish this. If it is a standard captured fleet (all trucks are the same width, length, height and bed height), then one (1) dock height can possibly serve them all.