If there are several different vehicles with varying dimensions at your distribution centre and they all need to use the same loading bay. Special transport like refrigerated trucks are higher due to the overhead refrigeration units. Tankers and city vans and other variations are also possible. A general rule is to determine the average floor height of both the lowest and the highest loaded vehicle. Also take into consideration the frequency of the different types of vehicles. Make your plans based on the 80:20 rule.