Free CDL Tanker Endorsement Practice Test 2026
The Tanker (N) endorsement is required to haul liquids or gases in bulk tanks. It covers the effects of liquid surge, high center of gravity, outage, baffles, and the special handling required for tank vehicles.
What is 'liquid surge' in a tank vehicle?
About the CDL Tanker Endorsement Test
Hauling liquid in bulk changes how a truck handles, and the Tanker endorsement test is built around that physics. Liquid surge - the wave that sloshes forward when you brake - can shove a tanker through an intersection or trigger a rollover on a curve. The exam covers outage (the space liquids need to expand), the difference between baffled and smooth-bore tanks, the high center of gravity that makes tankers tip easily, and the gentle, anticipatory braking and steering that keep the load under control.
What's on the CDL Tanker Endorsement knowledge test
The Tanker Endorsement knowledge test is written from Section 8 (Tank Vehicles) of the national CDL manual, the text every state's CDL manual follows. You take it only if you need the N endorsement or drive a vehicle that requires it.
Federal rules fix the pass mark at 80 percent for every CDL knowledge test, but leave the number of questions to each state, so check your own state's CDL manual for the exact count. This practice test uses all 13 questions in our Tanker Endorsement bank, each checked against the manual page shown with it.
- Source manual
- National CDL Manual, Section 8 (Tank Vehicles)
- Number of questions
- Set by each state: federal rules require a set number of questions, with a prescribed number from each knowledge area (49 CFR 383.133)
Manual sections this test is drawn from
- Section 8: Tank Vehicles - Inspecting Tank Vehicles, Driving Tank Vehicles, Safe Driving Rules
Sample questions from this test, with answers
Want to test yourself first? Take the test above before reading these. Every answer below is checked against the source shown.
1. How should you drive a tank vehicle through a curve?
- A. Keep the posted curve speed the whole way
- B. Brake firmly in the middle of the curve
- C. Coast through it with the clutch pushed all the way in
- D. Slow before it, then speed up slightly through it (correct)
Why: Slow down before the curve, then accelerate slightly through it. A curve's posted speed can be too high for a tank vehicle.
Source: National CDL Manual, p.8-2 (PDF p.104), 8.3.3 Curves
2. How are bulkheads different from baffles in a liquid tank?
- A. Bulkheads have holes to let liquid flow
- B. Bulkheads stop side-to-side surge only
- C. Bulkheads are used only in food tanks
- D. Bulkheads divide it into smaller tanks (correct)
Why: Bulkheads divide a tank into several smaller tanks, while baffles are bulkheads with holes that let the liquid flow through. When loading divided tanks, watch the weight distribution.
Source: National CDL Manual, p.8-2 (PDF p.104), 8.2.3 Bulkheads
3. How should you brake a tank vehicle to control surge?
- A. Brake early and keep steady pressure (correct)
- B. Brake late and release just before stopping
- C. Pump the brakes quickly as you stop
- D. Use only the trailer hand valve
Why: Keep steady pressure on the brakes and do not release too soon when coming to a stop. Brake far ahead of the stop and leave extra following distance.
Source: National CDL Manual, p.8-2 (PDF p.104), 8.3.2 Controlling Surge
4. What is 'liquid surge' in a tank vehicle?
- A. Pressure building as the liquid warms up
- B. Liquid leaking out from a loose or worn manhole cover
- C. Liquid moving back and forth in a part-full tank (correct)
- D. Fuel flowing too quickly during unloading
Why: Surge comes from liquid moving in a partially filled tank. When you stop, the wave hits the end of the tank and pushes the truck in the direction the wave is moving.
Source: National CDL Manual, p.8-1 (PDF p.103), 8.2.2 Danger of Surge
5. Before driving a tank vehicle, what must be true of its valves and manhole covers?
- A. Valves may be open if the tank is full
- B. Manhole covers may be left cracked
- C. They must be closed and not leaking (correct)
- D. Only the discharge valve must be shut
Why: A tank vehicle must not be driven with any valve or manhole cover open. Leaks are the most important thing to check for, and hauling liquids in a leaking tank is a crime.
Source: National CDL Manual, p.8-1 (PDF p.103), 8.1.2 Check Special Purpose Equipment
6. What is 'outage' in a cargo tank?
- A. A leak in the tank's discharge valve
- B. Room left so the liquid can expand (correct)
- C. The weight of liquid the tank can hold
- D. A period when the pump stops working
Why: A cargo tank should never be filled to the top, because liquids expand as they warm. Different liquids expand by different amounts, so each needs its own amount of outage.
Source: National CDL Manual, p.8-2 (PDF p.104), 8.2.6 Outage
Other CDL Endorsement Tests
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