Which CDL knowledge tests do you need?
Before you get a commercial learner's permit, you pass one or more knowledge tests at your state's licensing office. Which ones depends on the vehicle you will drive.
| License | Vehicle | Knowledge tests |
|---|---|---|
| Class A | A combination of 26,001 lb or more where the towed unit is over 10,000 lb, such as a tractor-trailer | General Knowledge, Combination Vehicles, and Air Brakes if the vehicle has them |
| Class B | A single vehicle of 26,001 lb or more, including one towing a trailer of 10,000 lb or less, such as a bus, dump truck or box truck | General Knowledge, and Air Brakes if the vehicle has them |
| Class C | A smaller vehicle that carries 16 or more people counting the driver, or placarded hazardous materials | General Knowledge, plus the Passenger or HazMat endorsement |
Your state may add rules of its own: Texas has a state rules test, New York has a metal coil endorsement test, and California needs a commercial license for some vehicles the federal rules leave out. Check your state.
The tests
General Knowledge
Everyone who applies for a commercial learner's permit takes this test, for Class A, B or C.
554 practice questions in 34 chapters.
Air Brakes
Take it if you will drive a vehicle with air brakes. Without it, your license carries an air-brake restriction.
164 practice questions in 5 chapters.
Combination Vehicles
Needed for a Class A license: a tractor-trailer or other vehicle that tows a heavy trailer.
129 practice questions in 6 chapters.
Passenger (P)
For the P endorsement, to drive a bus or other vehicle that carries 16 or more people, counting the driver.
87 practice questions in 7 chapters.
School Bus (S)
For the S endorsement. School bus drivers also need the Passenger endorsement.
108 practice questions in 7 chapters.
Tank Vehicle (N)
For the N endorsement, to haul liquids or gases in a tank.
48 practice questions in 4 chapters.
Doubles and Triples (T)
For the T endorsement, to pull two or three trailers. Class A only.
69 practice questions in 4 chapters.
Hazardous Materials (H)
For the H endorsement, to haul placarded hazardous materials. It also needs a federal background check; your state explains how.
204 practice questions in 8 chapters.
Texas Commercial Rules
Texas only. Texas applicants take this state test before the others.
38 practice questions in 7 chapters.
New York Metal Coil (M)
New York only. For the M endorsement, to haul metal coils of 5,000 lb or more, alone or bundled. Based on New York's own metal coil manual.
46 practice questions in 4 chapters.
This is practice for the knowledge test. It is not Entry-Level Driver Training and does not count toward any federal training requirement.