Tanker Endorsement Practice Test 2026
Free tanker endorsement practice test for 2026: 20 questions with answers on surge, baffles and braking, plus how to add the N endorsement to your CDL.
What's on the Tanker CDL test
Answering from memory beats re-reading — retrieval practice roughly doubles what you remember a week later. These free questions are modeled on the official Tanker CDL knowledge test.
- Official test
- 20
- Practice questions here
- 20
- To pass
- 16/20 correct (80%)
- Updated
- September 2026
- 100% free
Hauling hazmat in a tanker? That’s the X endorsement
The X endorsement is the combined tank vehicle + hazardous materials endorsement (49 CFR 383.153). To earn it you pass both knowledge tests: the tanker test — knowledge-only, no skills test (49 CFR 383.93(c)) — and the hazmat test, which additionally requires a TSA security screening (49 CFR 383.71, part 1572).
Federally, a “tank vehicle” means tanks over 119 gallons individually and 1,000+ gallons combined (49 CFR 383.5) — if that’s your rig and the load is placarded, you need the X, not just the N.
HazMat practice testTanker (N) endorsement at a glance
- Endorsement code
- N — tank vehicle (X when combined with hazmat)
- Test type
- Knowledge test only — no skills (driving) test
- Allowed on a learner’s permit
- Yes — empty tanks only while on a CLP
- Entry-level driver training
- Not required for the N endorsement
- Where to study
- The “Tank Vehicles” section of your state CDL manual (Section 8 in the model manual)
- Official test
- 20 questions under the AAMVA model most states use — your state may differ
- Pass mark
- 80% — 16 of 20 correct (federal, 49 CFR 383.135)
- This practice set
- 20 questions with explanations, free, no sign-up
Show all 20 practice questions with answers
How do baffles in baffled tanks contribute to managing liquid movement?
- Reducing the speed of the truck
- Increasing fuel efficiency
- Controlling both forward and backward liquid surges
Correct answer: Controlling both forward and backward liquid surges
Baffles in tanks help stop the liquid from sloshing too much forward and backward. This makes it easier to control the truck when it's moving.
When filling up a tanker with 3 or 4 valves at its bottom, how should you position the valves?
- Locked
- Secured
- Closed
Correct answer: Closed
When filling up a tanker with 3 or 4 bottom valves, make sure those valves are tightly shut. This prevents any spills or leaks while loading.
When filling up and emptying tanks with bulkheads, the driver needs to ensure the weight is evenly distributed.
- TRUE
- FALSE
Correct answer: TRUE
TRUE. When filling or emptying tanks with dividers, it's important for drivers to make sure the weight is spread out evenly. This helps keep the truck stable and safe on the road.
On all tank vehicles the most important item to check is for:
- Broken seals
- Leaks
- Cracked hoses
Correct answer: Leaks
When checking tank vehicles, the most crucial thing to look for is leaks. This is because leaks can lead to loss of liquids, potentially causing accidents or environmental harm. Always ensure the tank is secure and leak-free to keep both you and the environment safe.
When driving, it's important to pay attention to the speed limits for curves and understand that...
- The posted speeds may not be slow enough for a tank truck
- Tank trucks have a higher center of gravity
- A rollover can still occur when traveling at posted speeds in a tank truck
- All of the above
Correct answer: All of the above
The correct answer is "All of the above."
A tank endorsement is required for certain vehicles that transport what?
- oversize loads.
- liquids or gases.
- general freight in boxes or pallets.
Correct answer: liquids or gases.
Federal regulations say a tank endorsement is needed to operate a tank vehicle that requires a CDL. A tank vehicle is a commercial motor vehicle carrying bulk liquid or gas in one or more tanks that are permanently or temporarily attached to the vehicle (49 CFR 383.5; 49 CFR 383.93).
Which statement best characterizes baffled tanks?
- Baffled tanks have double walls for extra insulation.
- Baffled tanks have bulkheads with openings that let liquid flow through to other smaller tanks inside the tank shell.
- Baffled tanks are equipped with external vents to reduce internal pressure.
Correct answer: Baffled tanks have bulkheads with openings that let liquid flow through to other smaller tanks inside the tank shell.
Baffled tanks are designed with special walls inside that have holes. These walls let liquids move through to smaller sections within the tank. This helps keep the liquid more stable and prevents it from moving around too much.
Why is it important to be aware of the required outage for the liquids you transport?
- Different liquids have the same outage requirements.
- All liquids can be safely transported without considering outage.
- For some of the heaviest liquids, you don't need to leave any clearance.
Correct answer: For some of the heaviest liquids, you don't need to leave any clearance.
Heavier liquids expand less, so they can often be filled to the top without risking overflow. Knowing each liquid’s expansion needs helps prevent spills and ensures safe, efficient transportation.
During loading, what should be the position of the tankers' manhole covers and vent covers?
- Tightly sealed with tape
- Loosely covered with cloth
- Closed correctly.
Correct answer: Closed correctly.
When loading a tanker, make sure the manhole covers and vent covers are properly closed. This keeps everything safe and secure.
What do you call the walls inside a tanker that have holes at both the top and bottom?
- Barriers
- Baffles
- Surfboards
- Partitions
Correct answer: Baffles
The correct answer is baffles. These are like walls inside a tanker truck's tank with holes on the top and bottom. They help keep the liquid from moving around too much when the truck is turning or stopping, making the drive safer.
Stop valves in a cargo tank...
- Are controlled remotely
- Close in an emergency
- Protect the tank and piping from rear end collisions
- Open automatically during maintenance
Correct answer: Close in an emergency
Stop valves in a cargo tank are special parts that automatically close if there's an emergency to prevent spills.
You’re driving at night with clear visibility and need to switch your headlights from high beams to low beams. You should reduce your speed so you can stop within what distance?
- the distance you could travel in the next 5 seconds.
- the distance you can see ahead.
- one car length.
Correct answer: the distance you can see ahead.
At night, regardless of the type of vehicle, you must travel slowly enough to be able to stop within the area illuminated by your headlights, because you cannot anticipate hazards beyond what your lights reveal. Low beams typically light only about 250 feet ahead. For example, a vehicle with air brakes traveling 45 mph may need up to about 346 feet to stop, meaning that at 45 mph on low beams you may not be able to stop in time for something you can see.
You should inspect the intake, discharge, and cut-off valves before driving, loading, or unloading the vehicle ___.
- To confirm the valves are properly labeled.
- To verify the color of the valves.
- To ensure they are in the correct position
Correct answer: To ensure they are in the correct position
Before driving, loading, or unloading your vehicle, you should check the intake, discharge, and cut-off valves to make sure they are in the right position. This helps prevent any problems during your trip.
Which of these facts is correct about how to steer in an emergency when driving a tanker?
- When making a quick steering movement, do not apply the brakes
- You should only use one hand on the steering wheel during quick movements.
- Turning the steering wheel slowly is safer in emergencies.
Correct answer: When making a quick steering movement, do not apply the brakes
When you need to steer quickly in a tanker, don't hit the brakes because it can lead to a skid or rollover. Quick and controlled steering is the way to prevent a crash without making things worse.
What should you inspect the tank's body or shell for?
- Leaks and discoloration
- Dents and leaks
- Cracks and rust
Correct answer: Dents and leaks
When inspecting a tank's body or shell, you should look for any dents and leaks. Dents can weaken the tank's structure, and leaks can cause the contents to escape, which might be dangerous or lead to waste. Checking for these issues helps ensure the tank is safe and in good condition.
A smooth bore tank is ___.
- A dry bulk cargo tank
- A tank which is portable
- A liquid tank without baffles
- A tank designed for compressed gases.
Correct answer: A liquid tank without baffles
A smooth bore tank is a special kind of tank used to hold liquids. It's different because it doesn't have inside barriers, known as baffles, that usually help to keep the liquid from moving around too much.
In what situations should you exercise extra caution when driving a smooth bore tanker combination?
- When loading or unloading
- While ascending a hill
- While descending a hill
- When starting and stopping
Correct answer: When starting and stopping
When driving a smooth tank truck, be very careful when starting or stopping. This is because the liquid inside can move a lot, making it hard to control the truck.
Which of the following statements about tanker vehicles are true?
- Tankers can turn over at the speed limits posted for curves.
- Much of the load's weight is carried high up off the road.
- Both of the above are true.
Correct answer: Both of the above are true.
Tank vehicles have a high center of gravity, usually about five or six feet above the ground. This makes tankers top-heavy and more likely to roll over than other vehicles. Tests show a tank vehicle can roll over even when traveling at the posted speed limit for a curve. To take a curve safely, slow to well below the posted limit.
Before loading, unloading, or driving a tanker, what precautionary steps should you take?
- Inspect the vehicle.
- Make sure your cargo is covered with a tarp.
- Check the weather forecast.
Correct answer: Inspect the vehicle.
Before you do anything with a tanker, like loading, unloading, or driving it, you need to carefully check the vehicle to make sure everything is in good condition and safe to use.
Empty trucks:
- Can carry more weight than full trucks.
- May require longer stopping distances than full ones
- Are easier to control during sharp turns.
Correct answer: May require longer stopping distances than full ones
Empty trucks might take longer to stop than trucks full of stuff.
What the tanker endorsement is — and who needs it
The tank vehicle endorsement — code N on your license — is required to drive any commercial motor vehicle designed to carry liquid or gaseous materials in a tank or tanks with an individual rated capacity of more than 119 gallons and an aggregate rated capacity of 1,000 gallons or more, whether the tank is permanently or temporarily attached to the vehicle or chassis.
That definition reaches beyond fuel tankers. A flatbed hauling temporarily attached portable tanks or totes is a tank vehicle once both capacity thresholds are crossed. The one carve-out written into the rule is an empty storage-container tank of 1,000 gallons or more that is not designed for transportation and is temporarily attached to a flatbed trailer — that is not a tank vehicle.
The endorsement rides on top of your license class: a straight-truck fuel tanker needs a Class B CDL plus N, and a tractor pulling a tank trailer needs a Class A plus N. If the load is a placarded hazardous material you also need the hazmat endorsement — the combination of tank vehicle and hazardous materials endorsements is printed as a single X code.
49 CFR 383.5 (tank vehicle), 383.93(b)(3), 383.153(a)(9)(iii) and (v)
Drivers who typically need the N endorsement
If your job puts you behind the wheel of any of these, plan on the tanker test:
- Fuel, propane and heating-oil delivery trucks, whether straight trucks or tractor-trailers.
- Bulk liquid haulers — milk, water, juice, chemicals, asphalt, liquid fertilizer.
- Flatbeds carrying temporarily attached portable tanks or intermediate bulk containers over 119 gallons each and 1,000 gallons combined.
- Compressed-gas carriers: the federal definition covers gaseous materials as well as liquids.
- Dry-bulk pneumatic trailers are a gray area — the federal definition names liquid or gaseous materials, so confirm your state’s and employer’s policy before assuming.
49 CFR 383.5
What is on the tanker knowledge test
Federal rule fixes the subject matter every state’s tank vehicle test must cover. Expect questions on:
- Causes, prevention and effects of cargo surge on vehicle handling.
- Proper braking when the tank is empty, full and partially full.
- How baffled and compartmented tanks handle compared with unbaffled (smooth-bore) tanks.
- Differences in tank vehicle types and construction.
- How surge changes with liquids of different densities.
- Effects of road grade and curves with a full, half-full and empty tank.
- Proper use of emergency systems.
- Retest and marking requirements for DOT-specification tank vehicles.
49 CFR 383.119
How to add the tanker endorsement to your CDL
Hold a CDL or a commercial learner’s permit in the right class
The N endorsement can be added at the permit stage: it is one of only three endorsements allowed on a CLP (passenger, school bus and tank vehicle). A permit holder with N may only operate an empty tank vehicle, and never one that previously carried hazardous materials unless it has been purged of residue.
49 CFR 383.93(a)(2), 383.25(a)(5)(iii)
Study the tank vehicles section of your state’s CDL manual
Most states publish the AAMVA model manual, where tank vehicles is Section 8. The topics it covers are the federal knowledge areas listed above — surge, baffles, braking with partial loads, outage and product density. Then drill the practice set on this page until you are consistently above 80%.
Pass the tank vehicle knowledge test at your state licensing agency
Tanker is a knowledge-only endorsement — there is no separate skills (driving) test. You need at least 80% on the test, the same federal pass mark as every CDL knowledge test. Test and endorsement fees, appointment rules and retake waiting periods vary by state; use the state pages below for the agency that issues your license.
Find your state’s tanker practice test and agency49 CFR 383.93(c)(3), 383.135(a)(1)
Get the N printed on your license
States issue an endorsement only to drivers who pass the specialized test, and every state uses the same code letters, so an N earned in one state means the same thing everywhere. No entry-level driver training is required for the tanker endorsement — the ELDT rule applies to a first Class A or B license and to the passenger, school bus and hazmat endorsements.
49 CFR 383.93(a)(1), 383.153(a)(9), 383.71(a)(10)
Hauling placarded hazmat in a tank? Add the H to get an X
A tanker carrying a placarded hazardous material needs the hazmat endorsement too. That test has its own knowledge exam plus a TSA security threat assessment, and the combined credential is printed as X. Practice the hazmat test next.
HazMat CDL practice test49 CFR 383.153(a)(9)(v), 383.71(b)(8)
Tanker endorsement — questions and answers
Is there a driving test for the tanker endorsement?
No. Federal rule requires only a knowledge test for the tank vehicle endorsement. Compare the passenger and school bus endorsements, which require both a knowledge and a skills test. That is why tanker is one of the fastest endorsements to add.
49 CFR 383.93(c)
How many questions are on the tanker test, and what score do I need?
Under the AAMVA model most states use, the tank vehicle test has 20 questions; your state can use a different count, so confirm it in the state CDL manual. The pass mark is federal and the same everywhere: at least 80% — 16 of 20 correct. The practice set on this page also plays 20 questions, each with an explanation.
49 CFR 383.135(a)(1)
Do I need entry-level driver training (ELDT) for the tanker endorsement?
No. Since February 7, 2022, ELDT from a registered provider is required before a first Class A or Class B skills test, a first passenger or school bus skills test, or a first hazmat knowledge test. The tank vehicle endorsement is not on that list.
49 CFR 383.71(a)(10), 380.603
Can I add the tanker endorsement to my learner’s permit?
Yes. Passenger, school bus and tank vehicle are the only endorsements a commercial learner’s permit may carry. With N on a CLP you may drive only an empty tank vehicle, and not one that previously held hazardous materials unless it has been purged.
49 CFR 383.93(a)(2), 383.25(a)(5)
What is the difference between the N and X endorsements?
N is the tank vehicle endorsement on its own. X is the combined tank vehicle and hazardous materials endorsement — you earn it by passing both knowledge tests, and the hazmat half also requires a Transportation Security Administration threat assessment under 49 CFR part 1572. If your tank loads are placarded, you need the X.
HazMat CDL practice test49 CFR 383.153(a)(9), 383.71(b)(8)
Does a portable tank or tote on a flatbed count as a tank vehicle?
It can. The federal definition includes tanks temporarily attached to the vehicle or chassis, so a flatbed with portable tanks over 119 gallons each and 1,000 gallons or more combined is a tank vehicle. The exception is an empty storage-container tank of 1,000 gallons or more, not designed for transportation, temporarily attached to a flatbed.
49 CFR 383.5
Official sources
- 49 CFR 383.5 — Definitions (tank vehicle)
- 49 CFR 383.119 — Requirements for tank vehicle endorsement
- 49 CFR 383.93 — Endorsements
- FMCSA — Commercial Driver’s License
Fees, the licensing agency and appointment rules vary by state — pick your state below for the agency that issues your license.
Federal rules on this page last reviewed against the eCFR on .
Practice the Tanker test by state
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