25 realistic Tank Vehicles practice questions for Iowa CDL applicants. Required for: Vehicles with liquid or gaseous tanks ≥1,000 gallons. Official test: 20 questions, 16 correct to pass.
Question 1 of 25 · Tank Types
What is a "smooth bore" tank?
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A.
A tank with internal baffles
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B.
A tank without internal baffles or compartments
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C.
A heated tank
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D.
A two-compartment tank
Correct answer: B.
Smooth-bore tanks have no internal baffles, so liquid surge is unrestrained.
Question 2 of 25 · Tank Types
What is "compartmented tanks"?
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A.
Tanks split into multiple sections
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B.
Tanks made for grain
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C.
Tanks made for hazardous materials only
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D.
Tanks with one large interior
Correct answer: A.
Compartmented tanks have multiple sections so different liquids can be carried separately.
Question 3 of 25 · Vehicle Dynamics
Why is the high center of gravity dangerous?
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A.
It increases rollover risk
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B.
It makes the vehicle more aerodynamic
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C.
It improves traction
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D.
It reduces braking force
Correct answer: A.
A high CG raises rollover risk, especially in turns or sudden maneuvers.
Question 4 of 25 · Inspection
What's the importance of the tank shell's integrity?
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A.
It contains the cargo and prevents leaks
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B.
It supports the chassis
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C.
It absorbs shock
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D.
It connects to the brakes
Correct answer: A.
A sound tank shell prevents leaks and contains pressure from the cargo.
Question 5 of 25 · Loading
What is a vapor recovery system?
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A.
A way to recover heat
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B.
A system to recover vapors during loading and unloading to reduce emissions
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C.
An air brake component
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D.
A backup pump
Correct answer: B.
Vapor recovery captures vapors during transfer to limit emissions.
Question 6 of 25 · Vehicle Dynamics
Why must drivers be especially careful when starting and stopping a tanker?
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A.
Surge can cause loss of control
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B.
Engine torque is too high
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C.
Brakes are weaker
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D.
Steering is harder
Correct answer: A.
Surge during starts and stops can shove the vehicle and cause loss of control.
Question 7 of 25 · Tank Types
What's a key difference between compartmented and smooth-bore tanks?
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A.
Compartmented tanks reduce surge between sections
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B.
Smooth-bore tanks have less surge
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C.
They are the same in terms of surge
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D.
Compartmented tanks are always larger
Correct answer: A.
Compartmented tanks reduce overall surge by limiting movement to each section.
Question 8 of 25 · Loading
How can drivers tell if a tank is properly loaded?
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A.
Check that all compartments are filled within outage limits
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B.
Check the weight distribution
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C.
Confirm valves are closed
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D.
All of the above
Correct answer: D.
Verify outage, weight distribution, and closed valves before moving.
Question 9 of 25 · Loading
Why is it important not to overload tank vehicles?
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A.
Overloading exceeds weight limits
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B.
It increases risk of tank rupture
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C.
It changes vehicle handling
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D.
All of the above
Correct answer: D.
Overloading is illegal and unsafe; it changes handling and stresses the tank.
Question 10 of 25 · Placards
Why are tankers required to have specific markings?
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A.
To identify the cargo and any hazards
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B.
To make them more visible
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C.
For tax purposes
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D.
For insurance only
Correct answer: A.
Markings identify cargo and any hazards for emergency responders and others.
Question 11 of 25 · Adverse Conditions
What's the safe way to handle a tanker on icy roads?
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A.
Slow down and increase following distance
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B.
Use chains if required
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C.
Avoid sudden braking and steering
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D.
All of the above
Correct answer: D.
Reduced speed, chains where required, and smooth inputs reduce risk on ice.
Question 12 of 25 · Backing
What should a driver do before backing a tanker?
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A.
Check the path with a helper
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B.
Look behind the vehicle
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C.
Walk around the vehicle to check clearances
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D.
All of the above
Correct answer: D.
Use a helper, walk-around, and check the path before backing.
Question 13 of 25 · Speed Management
When should tank drivers especially reduce speed?
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A.
On wet or slippery roads
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B.
On curves
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C.
On ramps
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D.
All of the above
Correct answer: D.
Slow down on wet roads, curves, and ramps — all increase rollover risk.
Question 14 of 25 · Tank Types
What is the purpose of internal baffles?
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A.
To reduce side-to-side surge
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B.
To reduce forward and back surge
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C.
To prevent leaks
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D.
To increase tank size
Correct answer: B.
Baffles reduce front-to-back surge but do not stop side-to-side surge.
Question 15 of 25 · Speed Management
What should you do when going around curves with a tanker?
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A.
Slow down well below the posted speed
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B.
Drive at the posted speed limit
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C.
Use the engine retarder
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D.
Lock the brakes
Correct answer: A.
Take curves at speeds well below the posted limit to avoid rollovers.
Question 16 of 25 · Adverse Conditions
What's the safe way to handle a tanker in heavy wind?
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A.
Slow down and grip steering firmly
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B.
Speed up to maintain control
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C.
Use the engine retarder
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D.
Lock the brakes
Correct answer: A.
High winds destabilize tankers; slow down and steer firmly.
Question 17 of 25 · Loading
Why must tanker drivers be careful when refueling?
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A.
Risk of fire from spills
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B.
Risk of cargo contamination
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C.
Risk of overloading
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D.
Both A and B
Correct answer: D.
Spills can ignite and cargo can be contaminated by fuel.
Question 18 of 25 · Vehicle Dynamics
What's the most important thing to remember about driving a tanker?
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A.
Be aware of liquid surge and high center of gravity
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B.
Drive faster to maintain schedule
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C.
Skip pre-trip inspections
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D.
Ignore weather conditions
Correct answer: A.
Surge and CG awareness are the cornerstones of safe tanker driving.
Question 19 of 25 · Vehicle Dynamics
What's a key safety feature in modern tankers?
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A.
Automatic emergency braking
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B.
Stability control systems
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C.
Reinforced tank shells
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D.
All of the above
Correct answer: D.
Modern tankers often combine ABS, stability control, and reinforced shells for safety.
Question 20 of 25 · CDL Rules
How are tanker drivers trained for hazardous cargo?
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A.
Same as regular drivers
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B.
They receive specialized training and may need HazMat endorsement
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C.
No specific training required
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D.
They are trained by the shipper
Correct answer: B.
Hazardous tankers require additional training and often a HazMat endorsement.
Question 21 of 25 · Vehicle Dynamics
How do drivers minimize side-to-side surge?
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A.
Avoid abrupt lane changes and turns
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B.
Take turns wide and slow
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C.
Use partial loads
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D.
Both A and B
Correct answer: D.
Smooth, slow inputs and wide turns help reduce side-to-side surge.
Question 22 of 25 · Tank Types
What is a baffled tank?
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A.
A tank with internal walls that have holes to slow surge
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B.
A tank with separate compartments
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C.
A tank with a smooth interior
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D.
A tank with no walls inside
Correct answer: A.
Baffles slow forward and back surge, but not side-to-side surge.
Question 23 of 25 · Loading
What is "outage" in tank operations?
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A.
Lost electricity
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B.
Empty space allowed in a tank for liquid to expand
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C.
Tank failure
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D.
Loss of brake pressure
Correct answer: B.
Liquids expand with heat. Outage is the empty space left for that expansion.
Question 24 of 25 · Inspection
What is the proper way to inspect a tank before driving?
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A.
Check valves, manhole, and tank shell for leaks and damage
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B.
Just check the tires
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C.
Only inspect the engine
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D.
Skip inspection if you're in a hurry
Correct answer: A.
Inspect valves, manhole, shell, hoses, and other tank components every pre-trip.
Question 25 of 25 · Loading
What is "outage" requirement for liquids that expand a lot?
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A.
Larger outage required
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B.
Less outage required
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C.
No outage required
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D.
Outage doesn't depend on the liquid
Correct answer: A.
Liquids that expand more (e.g., LPG) require greater outage in the tank.
About the Tank Vehicles Test
The Tank Vehicles test covers inspecting tank vehicles, driving tank vehicles, surge and liquid movement, baffled and unbaffled tanks, outage, and safe driving rules unique to large liquid loads. Tank vehicles handle very differently from dry-freight vehicles because liquid surge can shove the vehicle in the direction the wave moves.
The Iowa Department of Transportation — Motor Vehicle Division administers this knowledge test as part of its commercial driver license program. To earn the Tank Endorsement (N) on your Iowa CDL, you need to score at least 16 out of 20 on the official version.
Topics covered on this practice test
- Loading: 6 questions
- Tank Types: 5 questions
- Vehicle Dynamics: 5 questions
- Inspection: 2 questions
- Adverse Conditions: 2 questions
- Speed Management: 2 questions
- Placards: 1 question
- Backing: 1 question
- CDL Rules: 1 question
How to use this practice test
- Read each question carefully. CDL questions are written precisely — small wording differences matter.
- Click "Show Answers & Explanations" only after answering every question. Don't peek mid-test.
- Read the explanation for every question, even ones you got right. The reasoning is more important than the answer.
- Repeat the test until you score 100%. The questions are deterministic per state, so you can track your improvement over multiple sessions.
- Move on to the other endorsement tests for Iowa until you're ready for the official exam.
Tips specific to the Tank Vehicles test
Tank vehicle questions focus on liquid surge, outage, smooth-bore versus baffled tanks, high center of gravity, and the special braking and turning techniques required to keep a partially-loaded tank under control. Expect several questions about leak response and load distribution.