CDL Tanker Practice Test

Endorsement Code: N

The Tanker endorsement (N) is required to drive a commercial vehicle designed to transport liquid or gaseous materials in a tank or tanks rated at 119 gallons or more. Liquid cargo behaves differently from solid freight -it surges and shifts, changing the vehicle's center of gravity. This endorsement ensures drivers understand these unique handling challenges.

Requirements

Hold a valid CDL (Class A, B, or C)
Pass the Tanker knowledge test at your state DMV
Complete Entry-Level Driver Training (ELDT) through a registered provider (for first-time tanker endorsement)
If transporting hazardous materials in a tank, you also need the HazMat endorsement (creating a Tank/HazMat combination, or 'X' endorsement)
Be at least 18 for intrastate hauling or 21 for interstate

What's on the Test

The Tanker knowledge test usually has 20 to 30 multiple-choice questions with an 80% passing score. Questions focus on liquid surge and its effect on vehicle handling, the dangers of partial loads vs. full loads, proper braking and cornering techniques for tank vehicles, baffled vs. unbaffled tanks, outage requirements (why tanks are never filled completely), and emergency procedures. If you are combining the tanker endorsement with HazMat (X endorsement), expect additional questions on hazardous liquid transport.

Study Tips

Understand liquid surge -a partially loaded tank is more dangerous than a full one because liquid has room to slosh and shift the center of gravity

Know the difference between baffled and smooth-bore (unbaffled) tanks and how each handles liquid surge

Remember that you should never fill a tank completely -outage space is required for liquid expansion

Study the specific braking techniques for tankers: brake early, brake gradually, and avoid sharp turns at speed

Learn why tank vehicles have a higher center of gravity and are more prone to rollovers than other commercial vehicles

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Tanker FAQ

What is the difference between the N endorsement and the X endorsement?

The N endorsement is for tanker vehicles only, meaning liquid or gas cargo in non-hazardous quantities. The X endorsement is a combination of Tanker (N) and HazMat (H), required when you transport hazardous materials in a tank vehicle -such as fuel tankers or chemical tankers. To get an X endorsement, you must pass both the tanker and HazMat knowledge tests.

Why is a partial load more dangerous than a full tank?

A partially filled tank allows liquid to slosh from side to side and front to back, creating liquid surge. This surge can push the vehicle in the direction the liquid moves, making it harder to control during braking, turning, and lane changes. A full tank has minimal surge because there is little room for the liquid to move.

What are baffles in a tank vehicle?

Baffles are internal walls inside a tank that have holes in them to allow liquid to flow through. They reduce the front-to-back surge of liquid, making the vehicle easier to control during braking and acceleration. However, baffles do not prevent side-to-side surge. Smooth-bore (unbaffled) tanks have no internal walls and are used for liquids like milk that must be easily sanitized.

Do I need ELDT for a tanker endorsement?

Yes. Since February 2022, first-time tanker endorsement applicants must complete Entry-Level Driver Training (ELDT) through an FMCSA-registered training provider. This applies to anyone adding the N endorsement for the first time. It does not apply if you are renewing or transferring an existing tanker endorsement.

What vehicles require a tanker endorsement?

Any commercial vehicle designed to transport any liquid or gaseous material in a tank or tanks with an individual rated capacity of 119 gallons or more, or a combined rated capacity of 1,000 gallons or more, requires a tanker endorsement. This includes fuel tankers, water trucks, milk tankers, and portable tank containers.

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