What are the eight CDL knowledge tests?

General Knowledge, Air Brakes, and Combination Vehicles are the core tests; Hazardous Materials, Passenger, School Bus, Tanker, and Doubles / Triples are the five endorsements. The matrix on this page shows all eight and who needs which.

Which tests are endorsements?

Hazardous Materials (H), Passenger (P), School Bus (S), Tanker (N), and Doubles / Triples (T) are the endorsements. Each allows you to carry something specific or drive a specific type of combination, and each is its own knowledge test.

The CDL knowledge tests

Eight tests a CDL candidate can take. Three are core; five are endorsements. The matrix below shows all eight and who needs which.

The requirement matrix, unfilled

The eight CDL knowledge tests and which class and cargo selections require them.
Test	A	B	C	P Passengers	S School	H Hazmat	N Tanker	T Dbl/Tri
General Knowledge
Air Brakes
Combination Vehicles
Hazardous Materials
Passenger
School Bus
Tanker
Doubles / Triples

How to read it

required You must pass this test for that selection.
optional You may take it; it is not demanded by that selection.
not required Struck through: that selection never asks for this test.

Federal The eight tests are written to the knowledge areas every state is required to test, so this table is the same table in every state. Which questions you are asked, and what the test costs, is your state’s.

The eight tests

General Knowledge 60 questions Air Brakes 25 questions Combination Vehicles 25 questions H Hazardous Materials what it covers · no bank yet P Passenger what it covers · no bank yet S School Bus what it covers · no bank yet N Tanker what it covers · no bank yet T Doubles / Triples what it covers · no bank yet

Air brakes is not an endorsement

Air brakes removes a restriction rather than adding an endorsement. A licence issued to a driver who tests in a vehicle with air brakes carries no restriction; one issued after a test in a vehicle without air brakes carries an “L” restriction against air-brake vehicles. Most heavy vehicles use air brakes, which is why most drivers take it.

This site prepares for a written knowledge test. It is not driver training, it is not ELDT, and nothing on it substitutes for your state's CDL manual or a registered training provider. Air brake procedure, coupling, load securement and hazardous-materials handling are safety-critical, and this site never teaches them as something to do.

Common questions

What are the eight CDL knowledge tests?: General Knowledge, Air Brakes, and Combination Vehicles are the core tests; Hazardous Materials, Passenger, School Bus, Tanker, and Doubles / Triples are the five endorsements. The matrix on this page shows all eight and who needs which.
Is air brakes an endorsement?: No. Air brakes removes a restriction rather than adding an endorsement. A licence issued to a driver who tests in a vehicle with air brakes carries no restriction; one issued after a test in a vehicle without air brakes carries an 'L' restriction. Most drivers take it because most heavy vehicles have air brakes.
Which tests are endorsements?: Hazardous Materials (H), Passenger (P), School Bus (S), Tanker (N), and Doubles / Triples (T) are the endorsements. Each allows you to carry something specific or drive a specific type of combination, and each is its own knowledge test.