CDL License Classifications:
The Federal standard requires States to issue a CDL license to drivers according to the following CDL license classifications:
Class A — Any combination of vehicles with a GVWR of 26,001 or more pounds provided the GVWR of the vehicle(s) being towed is in excess of 10,000 pounds.
Class B — Any single vehicle with a GVWR of 26,001 or more pounds, or any such vehicle towing a vehicle not in excess of 10,000 pounds GVWR.
Class C — Any single vehicle, or combination of vehicles, that does not meet the definition of Class A or Class B, but is either designed to transport 16 or more passengers, including the driver, or is placarded for hazardous materials.
For more complete details and information please refer to 49 CFR 383.91
Source: 49 CFR 383