Tanker Vehicles
Handle the surge, stability, and stopping challenges of liquid loads.
Liquid cargo moves, and everything difficult about tankers follows from that. Learn how surge affects stopping and starting, why a high center of gravity changes safe cornering speed, and how baffles and compartments alter handling, so you can answer from the physics of the load instead of guessing at isolated rules.
The rules that matter
- Liquid surge combined with a high center of gravity is the leading cause of tanker rollovers, so slow well below the posted speed for every curve.
- Baffles cut front-to-back surge but do nothing for side-to-side; a smooth-bore tank with no baffles surges the hardest.
- Tanks are never loaded completely full — liquids expand, and the empty space, called outage, leaves room for it.
- Even a partly filled tank surges, so brake early and smoothly and leave extra following distance.
- A loaded tanker stops before railroad crossings and takes curves and ramps far slower than the signs, which are set for cars.
- A placarded tanker stopped on a public road is attended by its driver, on the vehicle or within 100 feet with it in clear view.
The lessons in this module
Each lesson is one short set of questions. If you've missed questions in this module before, a few come back at the start. Progress saves automatically; sign in only if you want cross-device sync.
Lesson videos
1 lesson · See all →Read this in the handbook
Look for these sections: Tank Vehicles, Environmental Compliance.
This content comes from the federal FMCSA regulations (49 CFR), not a state handbook, so the rules are the same nationwide. Your state agency may add its own endorsement requirements on top.
Where these rules come from
We do not copy official handbooks — most states do not allow it. What we do instead: state the rule in our own words, then name the official document behind it. 101 questions in this module cite 9 official documents, none checked earlier than 2026-05-17. The 6 most-cited are below.
| Official document | Sections cited |
|---|---|
FMCSA Commercial Driver License Manual ↗ National · Checked 2026-08-01 | Section 8: Tank Vehicles |
FMCSA CDL Testing System — Tankers ↗ National · Checked 2026-06-30 | Tanker Vehicles — Anti-Surge Devices, Tanker Vehicles — Food Grade Tanks, Tanker Vehicles — Full Tank Handling |
FMCSA Commercial Driver License Manual ↗ National · Checked 2026-05-17 | Section 8: Tank Vehicles |
FMCSA Commercial Driver's License Manual ↗ National · Checked 2026-06-14 | Section 8 - Tank Vehicles, Section 8.1 - High Center Of Gravity, Section 8.1 - Inspecting Tank Vehicles |
49 CFR § 177.834 ↗ National · Checked 2026-06-30 | Tanker Vehicles — Flammable Liquids Safety |
49 CFR § 178.337-18 ↗ National · Checked 2026-06-30 | Tanker Vehicles — Specification Plate |
Opening a source takes you to the agency's own site, never to a copy of ours. If a source is out of date or broken, say so from any question.
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Review these questions
When stopping a tanker, you should brake:
- A. Gently and well in advance
- B. Hard and quickly
- C. Only at the last moment
- D. Using only the parking brake
Show answer
A. Gently and well in advance — Brake gently and early when driving a tanker. Hard braking causes liquid to surge forward, pushing the vehicle and extending stopping distance.
Universal rule · checked against FMCSA Commercial Driver License Manual — Section 8: Tank Vehicles · verified 2026-05-17
How should you brake a partly loaded tanker approaching a stop?
- A. With the trailer brakes only
- B. Late and firmly to settle the load
- C. In short bursts to break up surge
- D. Early and smoothly, leaving extra room
Show answer
D. Early and smoothly, leaving extra room — Surge pushes hardest at the end of a stop, so braking early and gently leaves room for the load to move without shoving you forward.
Universal rule · checked against FMCSA Commercial Driver License Manual — Section 8: Tank Vehicles · verified 2026-07-29
What should you check about a tank's sight glass or gauge?
- A. Painted over for privacy
- B. Readable and not damaged
- C. Removed during transport
- D. Loose enough to rotate
Show answer
B. Readable and not damaged — It is how the driver knows what is actually aboard, and a cracked or fogged gauge turns loading into guesswork.
Universal rule · checked against FMCSA Commercial Driver License Manual — Section 8: Tank Vehicles · verified 2026-07-30
What should you check on a tank's shell and seams during inspection?
- A. That the paint color matches
- B. No dents, leaks or corroded areas
- C. That the shell is warm to touch
- D. That the seams are freshly welded
Show answer
B. No dents, leaks or corroded areas — A dent or corroded seam is where a tank fails under pressure, so the shell is walked and looked over before every trip.
Universal rule · checked against FMCSA Commercial Driver License Manual — Section 8: Tank Vehicles · verified 2026-07-29
What is the primary hazard of a partially filled tanker compared to a full or empty tanker?
- A. Higher weight causes brake fade
- B. Lower center of gravity increases tire wear
- C. More liquid surge due to free liquid movement in the tank
- D. Reduced fuel efficiency
Show answer
C. More liquid surge due to free liquid movement in the tank — A partially filled tanker has free liquid that can surge violently. A full tank has no room to surge, and an empty tank has no liquid. The half-full condition is most dangerous.
Universal rule · checked against FMCSA CDL Testing System — Tankers — Tanker Vehicles — Partially Filled Tanks · verified 2026-06-30