Class A-Combination heavy vehicle: any combination of vehicles with a gross combination weight rating of 26,001 or more pounds, provided the gross vehicle weight rating of the vehicles being towed is in excess of 10,000 pounds. 

Class B-Heavy straight vehicle or other combination: any single motor vehicle with a gross vehicle weight rating of 26,001 or more pounds, or any such vehicle towing a vehicle with a gross vehicle weight rating that is not in excess of 10,000 pounds. 

Class C-Small vehicle:  any vehicle that does not fit the definition of a Class A or Class B vehicle and is either (a) designed to transport sixteen or more passengers including the driver or (b) is used in the transportation of hazardous materials.