In addition to the standard Commercial Drivers License required for truck drivers, tanker truck drivers must also obtain a tanker endorsement. This requirement applies not only to traditional tankers but also other types of trucks operating like tankers such as flatbeds, dry vans, box trucks, and refrigerated trucks if: The cargo includes liquid or gaseous individual containers larger than 119-gallon capacity. The containers are loaded, not empty. The total combined volume in the containers is 1,000 gallons.