Chapter 6. Commercial Driver's License Information Obtaining a CDL Permit and License Commercial vehicles are divided into 3 classes based on size, weight, and functionality. Each class requires a different CDL. In addition to classes, you may also get endorsements, which permit you to drive specific kinds of vehicles. For example, you'll need a special endorsement to drive a school bus. CDL Class 10/13 Test Required Class A (Combination Vehicle endorsement required) General Knowledge Written Exam Combination Endorsement Written Exam Road Exam Possible Endorsements and Required Tests H - Hazardous Materials N - Tank Vehicles P - Passenger Transport T - Double/Triples X - HazMat & Tank Vehicles L - Air Brakes S - School Bus Class B General Knowledge Written Exam Road Exam X - HazMat & Tank Vehicles L - Air Brakes S - School Bus Class C (Passenger, HAZMAT, or Airbrakes endorsement required UNLESS the endorsement requires one) General Knowledge Written Exam Road Exam Note: If upgrading to a Class C from a Class D, no road test is required UNLESS the endorsement requires one. X - HazMat & Tank Vehicles L - Air Brakes S - School Bus H - Hazardous Materials N - Tank Vehicles P - Passenger Transport H - Hazardous Materials N - Tank Vehicles P - Passenger Transport Written Exam Written Exam Written & Road Exam Written Exam Written Exam Written & Road Exam Written & Road Exam Written Exam Written Exam Written & Road Exam Written Exam Written & Road Exam Written & Road Exam Written Exam Written Exam Written & Road Exam Written Exam Written & Road Exam Written & Road Exam