Maine Tanker CDL Practice Test

This is a free 20-question practice test for the Tanker portion of the Maine Commercial Driver's License knowledge exam. Questions are pulled from a pool of 50 drawn from the AAMVA CDL Manual, which is the source document the Maine Bureau of Motor Vehicles uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Maine.

Question 1 of 20

When loading a cargo tank with flammable liquid, the driver must:

Stay alert, within 25 feet, with a clear view of the tank, and ready to handle emergencies
Leave for lunch
Smoke
Run the engine at high RPM

Correct. Federal rule: driver remains within 25 feet, alert, with a clear view, ready to act in case of overflow or emergency.

Question 2 of 20

A "tank vehicle" requiring an N endorsement is generally defined as:

Any commercial vehicle
A vehicle used to transport liquid or gaseous materials in a tank with rated capacity of 1,000 gallons or more, individual tanks of 119+ gallons
Only fuel trucks
Only vehicles over 80,000 lbs

Correct. The N endorsement is required for any commercial vehicle hauling liquid or gas in a permanently mounted tank or portable tank with rated capacity of 1,000+ gallons (and individual tanks of 119+ gallons).

Question 3 of 20

When unloading product from a cargo tank, you should:

Verify the receiving container can hold the load, bond and ground, control the flow rate, and remain within 25 feet for flammables
Walk away
Maximize flow rate
Smoke nearby

Correct. Pre-check receiving container, bond and ground, control flow rate to prevent splash and spill, and remain attentive for flammable liquids.

Question 4 of 20

Vapor recovery during loading:

Is used at terminals to capture flammable vapors
Replaces the cargo
Is forbidden
Is used only at night

Correct. Vapor recovery captures flammable vapors displaced as product is loaded, returning them to storage. Required at most modern fuel terminals.

Question 5 of 20

A double trailer tanker requires:

Both N (Tanker) and T (Doubles/Triples) endorsements, plus possibly H (Hazmat)
Only the N endorsement
No endorsements
Only the H endorsement

Correct. Pulling more than one tank requires Doubles/Triples (T) plus Tanker (N) endorsements. Add Hazmat (H) — together written X — for hazardous liquid loads.

Question 6 of 20

A heavy liquid load with a baffled tank may still surge:

Front-to-back, despite the baffles
Not at all
Less than smooth-bore but baffles do not stop side-to-side surge
None of the above

Correct. Baffles reduce front-to-back surge but do not affect side-to-side surge — bulkheads are typically transverse, not longitudinal.

Question 7 of 20

Front-to-back surge is most likely to cause:

The vehicle to be pushed forward when braking
The vehicle to roll over
Better braking
No effect

Correct. Front-to-back surge pushes the rig forward when you brake — drivers have been pushed through stop lines by an unexpected forward surge.

Question 8 of 20

Tankers have a high center of gravity because:

The driver sits high
The load is in a tall, narrow tank
The cargo is light
The cab is wide

Correct. A tank carries its load high above the road. The center of gravity is much higher than for a flatbed of the same weight, increasing rollover risk.

Question 9 of 20

Outage refers to:

Empty space left at the top of a tank to allow liquid expansion
The brake-out system
A power failure
A driver shortage

Correct. Outage is the empty space left at the top of a tank to allow liquid to expand as it warms. Different liquids require different outage percentages.

Question 10 of 20

When braking a partially filled smooth-bore tank, you should:

Brake hard at the last minute
Brake gently and start braking earlier than usual to compensate for surge
Use only the trailer hand valve
Pump the brakes

Correct. In smooth-bore tanks, surge is severe. Brake gently and earlier than you would in a dry-van trailer to avoid being pushed forward.

Question 11 of 20

You should never load a tank completely full because:

It is illegal in all states
Liquids expand when warmed and need outage; over-filling can rupture the tank
Trucks won't move
It saves no time

Correct. Liquids expand with temperature. Without outage, a warming load can over-pressurize and rupture the tank.

Question 12 of 20

A "bottom-loaded" tank:

Is loaded through bottom valves to reduce vapor and static
Is loaded only at the top
Carries cargo at the bottom only
Has no top vents

Correct. Bottom-loading uses sealed bottom-loading equipment with vapor recovery, reducing static and vapor escape compared to splash-loading from the top.

Question 13 of 20

A pressure-relief device that vents during transit:

Is a normal occurrence
Is a serious malfunction or over-fill — stop and investigate
Means the tank is empty
Means the load is cold

Correct. Continuous venting indicates over-pressure (often from over-fill or sun heating an over-filled tank). Stop and investigate; do not continue with a venting tank.

Question 14 of 20

When emergency-braking a smooth-bore tanker:

Brake hard
Anticipate forward surge that can throw your weight against the wheel and may push the rig past your intended stopping distance
Use only trailer brake
No special concern

Correct. Forward surge can dramatically push a smooth-bore tank rig further than expected. Plan stopping distance with significant additional margin.

Question 15 of 20

Bonding and grounding during product transfer:

Equalizes electrical potential between the tank and receiving container, preventing static-spark ignition
Charges the battery
Cools the load
Speeds delivery

Correct. Static electricity builds up during liquid transfer. Bonding (cable between tank and receiving container) plus grounding equalizes potential to prevent ignition.

Question 16 of 20

When carrying water (a non-hazmat liquid) in a tanker, you still need:

The N endorsement, because it is a tank vehicle
No endorsement
Only the H endorsement
Just a Class B

Correct. The N endorsement is based on the vehicle being a tank, not on the cargo. Even non-hazardous water requires the N endorsement if the tank meets size criteria.

Question 17 of 20

A loaded tanker on a curve is most likely to:

Roll over because surge plus high CG amplifies side forces
Skid in a straight line
Brake faster
Steer easier

Correct. Side surge plus high CG creates a tipping moment well above what a flat-bed of equal weight produces. Speed reduction in advance is the only safe answer.

Question 18 of 20

Side-to-side surge is most likely to cause:

Improved fuel economy
Rollover, especially on curves and in evasive maneuvers
No effect
Better braking

Correct. Side-to-side surge can amplify side-loading forces, contributing to rollover on curves and exit ramps.

Question 19 of 20

When you discover a leak in a cargo tank carrying flammable liquid:

Continue to the destination
Stop in a safe location, secure the area, contact emergency response and the carrier — never transfer cargo on the road
Try to drive around the leak
Pour water on it

Correct. A leaking flammable cargo tank is a major incident — secure the area, evacuate per the ERG, contact emergency services. Never attempt roadside cargo transfer.

Question 20 of 20

When driving with a load that has a low specific gravity (e.g., gasoline) versus high (e.g., asphalt), you should:

Drive the same
Adjust for the differences in surge dynamics, weight distribution, and braking
Skip braking
Run hot

Correct. Different products have different densities, surge characteristics, and weight distributions. Adjust speed and braking for the load.

About the Maine Tanker exam

Most states administer 20 Tanker questions and require 80% to pass. Topics include the unique handling of liquid loads, surge effects, baffles vs. smooth-bore, outage and expansion, inspection of the cargo tank, and emergency procedures.

The Maine Bureau of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the Tanker credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full Tanker question bank or browse all Maine CDL practice tests.