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Page 1 Tanker Test Study Guide for the CDL

General Information

The Commercial Driver’s License (CDL) Tanker test aims to determine whether or not potential drivers are able to competently and safely operate a tanker—or a vehicle designed to transport liquid or gas. Competency and safety are both pivotal in determining whether or not a driver should be working on the road; because tankers are large and exceedingly heavy, they handle quite differently than other vehicles and require vehicle-specific maintenance, inspection, and safety guidelines. The different components of the test are detailed below to provide drivers with items to study in order to pass the Tanker endorsement test.

Emergency Situations

As stated above, tankers are large, heavy machines and may not have the same halting capabilities as other commercial vehicles. For this reason, it is important to know and understand the proper procedure to come to a stop in an emergency, and what ought to be done in the event of an accident. When braking in an emergency, for instance, drivers should employ controlled or stabbed breaking, rather than using the emergency brake or locking the brakes. Additionally, note that tanks are more susceptible to overturning and, as a result, should be driven with a greater level of care, regardless of the fullness or the speed limit of the tank.

Weight Distribution

Drivers must know the limitations imposed upon their vehicles. As a tanker driver, you must not allow the tank to be filled to the top. Liquid may expand within the trailer, requiring some extra room to do so freely. Weight distribution impacts every aspect of your tanker’s performance, including the speed and acceleration the vehicle may achieve, the traction a vehicle may expect to have, and how the vehicle will handle. Because tankers are top-heavy, they are more easily overturned, may continue in a straight line following an attempt to turn or brake suddenly, and may be more difficult to maneuver at greater speeds. Understanding weight distribution is key to accurately and safely driving a tanker.

Driving with Baffles

Baffles are small holes in the walls of a tank, allowing liquid to flow through the walls and move more freely within the confines of the tank. Baffles are designed to allow more even distribution of fluid, improving drivability and safety, and allowing greater ease of movement when driving. But note that baffles do not necessarily guarantee freedom from accidents or overturning; they merely decrease the likelihood of a tanker-based accident and allow the liquid to surge from side-to-side, rather than front to back or top to bottom surges.


Though posted speed limits are typically understood as the absolute law on driving, most tanker drivers would do well to drive below the posted limit—particularly on curves and ramps. Though personal vehicles allow drivers to maintain the same speed during all terrain and driving grades, tankers are required to slow down before curve and only gently accelerate into a curve. They are required to go below the speed limit to effectively travel both up and down hill. Tankers possess a very high center of gravity and, as such, they are frequently more difficult to slow down and require greater care while driving. Maintain careful speeds at all times.