The highest level of CDL license is typically referred to as a Class A CDL. This classification allows drivers to operate the largest and most complex commercial vehicles, including tractor-trailers, combination vehicles with a gross combination weight rating (GCWR) of 26,001 pounds or more, with the towed vehicle(s) weighing more than 10,000 pounds. Class A CDL holders have the most extensive range of driving privileges within the commercial trucking industry.