Your CDL class decides which vehicles you may drive and which tests you must pass. The federal rule is short and exact. Here it is in plain English, with the weight numbers.
The three vehicle groups
| Class | Federal definition (49 CFR 383.91) | Typical vehicles |
|---|---|---|
| Class A (combination) | A combination of vehicles with a gross combination weight rating (GCWR) of 26,001 lb or more, provided the vehicle being towed has a GVWR over 10,000 lb. | Tractor-trailers; a truck pulling a heavy trailer |
| Class B (heavy straight) | A single vehicle with a GVWR of 26,001 lb or more, or such a vehicle towing a vehicle of 10,000 lb GVWR or less. | Straight trucks, dump trucks, large buses |
| Class C (small vehicle) | Any single vehicle or combination that is neither Class A nor Class B, but is designed to carry 16 or more passengers including the driver, or is used to transport hazardous materials as defined in 49 CFR 383.5. | Small buses and vans with 16+ seats; vehicles carrying hazmat |
GVWR is the manufacturer’s maximum loaded weight for one vehicle. GCWR is the maximum for the whole combination.
Heads up: “Class C” can mean two things
In the federal CDL rule, Class C is the small-vehicle group above. In many states, “Class C” is also the name of the regular, non-commercial driver’s license for cars. Check your state’s DMV manual so you study the right thing.
Moving up: what you must retake
Under 49 CFR 383.91(c), a driver who wants to operate a different group than the one on their CDL must retake and pass all the related tests, with two exceptions:
- A driver who passed the knowledge and skills tests for Class A may operate Class B or Class C vehicles, as long as they hold the required endorsements.
- A driver who passed the tests for Class B may operate Class C vehicles, with the required endorsements.
First-time Class A or B applicants and people upgrading to A or B must also complete entry-level driver training first. See our guide to ELDT.
Which class do you need?
- Hauling a tractor-trailer or a heavy trailer: Class A.
- Driving a straight truck, dump truck or a large bus: Class B.
- Carrying 16+ passengers in a smaller vehicle, or hazmat in a lighter one: Class C. Vehicles used to transport hazardous materials as defined in 49 CFR 383.5 also require the H endorsement (§ 383.93).
When in doubt, read the weight plate on the vehicle and compare it to the numbers above.
Try a free test, no account needed, and study in English and Spanish with audio.
Free practice testSee plans
Official sources
Keep reading
- ELDT: Entry-Level Driver Training Rules for a CDL
- DOT Medical Card for CDL Drivers: How Often Do You Need One?
Facts checked against the official text of 49 CFR (eCFR) as current on October 15, 2026. Rules change and each state adds its own: confirm with your DMV and the FMCSA. PassYourCDL is an independent study site, not affiliated with the FMCSA, the DOT or any DMV, and this is not legal advice.