Which CDL Tests Do I Need? Class A, B, C Explained

Every CDL applicant takes the General Knowledge test. What else you take depends on your license class, whether your test vehicle has air brakes, and the endorsements you want.

By license class

License	What it lets you drive (simplified)	Usual written tests
Class A	Combinations, like a tractor-trailer, with a combined weight rating of 26,001 lbs or more and a towed unit over 10,000 lbs	General Knowledge, Combination Vehicles, plus Air Brakes (if your vehicle has air brakes)
Class B	A single vehicle of 26,001 lbs or more, like a dump truck, box truck or many buses	General Knowledge, plus Air Brakes (if equipped)
Class C	Smaller vehicles that carry 16 or more people (driver included) or haul hazmat that needs placards	General Knowledge, plus the Passenger or Hazmat test

Add the Tanker test if you will drive a tank vehicle. These weight rules come from 49 CFR 383.91. Your state's manual has its own chart of which tests go with which class.

By endorsement

Endorsement	Letter	Written test	Extra steps
Hazardous Materials	H	Hazmat test	TSA background check with fingerprints
Tanker	N	Tanker test	Check your state
Passenger	P	Passenger test	Skills test in a passenger vehicle
School Bus	S	School Bus test, plus the Passenger test	Skills test
Doubles/Triples	T	Doubles/Triples test	Check your state
Tanker plus Hazmat	X	Tanker and Hazmat tests	TSA background check

Air brakes

If you fail the air brake part of the test, or take your skills test in a truck without air brakes, your license gets an air brake restriction. You cannot drive a truck with air brakes with that restriction. Most truck driving jobs need you to pass it, so plan to take it.

Not sure which class you need?

Ask the employer or school you are working with. Tractor-trailers are Class A. Dump trucks and box trucks are usually Class B.

If you are a first time Class A or B applicant, or a first time Passenger, School Bus or Hazmat applicant, entry-level driver training is also required. See CDL permit to license: every step.

Want practice on the tests most Class A drivers take? Try 10 exam-style questions built from the official CDL manual.

Practice more on the General Knowledge test, the Hazmat test, or the full list of CDL practice tests.

Get a study plan for exactly your tests

Pick your class and endorsements. The free Diagnostic shows you where to start.

Common questions

Can I get endorsements later?

Yes. You can add endorsements after you have your CDL. You take the written test, plus any skills test or background check that endorsement requires.

Does Class A cover Class B vehicles?

Yes, as long as you have the endorsements the vehicle needs. Federal rule 49 CFR 383.91 lets a Class A driver operate Class B and Class C vehicles with the right endorsements.

What is an air brake restriction?

If you fail the air brake part of the knowledge test, or take your skills test in a truck without air brakes, your license is restricted from driving any vehicle with air brakes.

Do I need a background check for hazmat?

Yes. The Hazmat endorsement requires a TSA security threat assessment that includes fingerprints.