Question 1 of 20
Cargo securement: the heaviest part of the load should be:
Correct. Loading heavy cargo to the front of the trailer over the drive axles helps with traction; loading to one side or top creates dangerous handling.
Texas Combination Vehicles CDL Practice Test
This is a free 20-question practice test for the Combination Vehicles portion of the Texas Commercial Driver's License knowledge exam. Questions are pulled from a pool of 55 drawn from the AAMVA CDL Manual, which is the source document the Texas Department of Public Safety Driver License Division 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 Texas.
Question 2 of 20
A safe practice when arriving at a destination is to:
Correct. Slow approach with mirror checks gives time to identify clearance issues and pedestrians.
Question 3 of 20
A jackknife happens when:
Correct. Jackknife is when the drive wheels skid and the trailer continues forward, causing the tractor to pivot — the rig folds at the fifth wheel like a closing knife.
Question 4 of 20
A high-mounted trailer kingpin is dangerous because:
Correct. If the trailer is too high, the fifth wheel slides under without the kingpin engaging the locking jaws. The trailer is not coupled and can drop when you pull away.
Question 5 of 20
On a tight curve or exit ramp, a tractor-trailer is most likely to roll over because:
Correct. Centripetal forces in a curve push the cargo outward; a high center of gravity multiplies the tipping moment. Slow before the curve.
Question 6 of 20
To make a trailer go where you want when backing, the steering wheel should:
Correct. Backing is opposite-direction steering: to swing the trailer right, turn the wheel left first, then correct as the trailer follows.
Question 7 of 20
The air lines connecting the tractor and trailer are:
Correct. The red glad-hand carries emergency/supply air; the blue glad-hand carries service air. They cross to keep matched colors when coupling.
Question 8 of 20
After connecting the trailer, before pulling away, you should always:
Correct. Always visually confirm: no gap between fifth wheel and trailer plate, jaws closed around the kingpin shank, locking lever fully in place.
Question 9 of 20
When backing a tractor-trailer in a straight line, you should:
Correct. When backing straight, watch the trailer in your mirrors and make small steering corrections to keep it tracking straight. Big corrections lead to jackknifing.
Question 10 of 20
Most jackknifes happen because:
Correct. Loss of traction on the tractor drive axles during braking — typically on slick surfaces or with overly aggressive braking — causes a jackknife.
Question 11 of 20
A "trailer skid" happens when:
Correct. When trailer wheels lose traction (often from over-application of trailer brakes alone), the trailer can slide sideways — a trailer skid or trailer swing.
Question 12 of 20
A sliding fifth wheel allows you to:
Correct. Sliding fifth wheels move forward to put more weight on drive axles or aft to reduce drive-axle weight, helping comply with axle-weight limits.
Question 13 of 20
When you supply air to the trailer for the first time after coupling, you should:
Correct. Charge the trailer system. Then test the trailer brake function by tugging gently or pulling the trailer-supply knob to confirm trailer brakes apply.
Question 14 of 20
When coupling, after backing under the trailer, you should:
Correct. A tug test confirms the kingpin is fully engaged. Skipping it is the leading cause of trailer drops shortly after coupling.
Question 15 of 20
Before uncoupling, you should:
Correct. Proper sequence: park level, lower landing gear to support the trailer, disconnect lines, release jaws, then pull forward slowly. Skipping any step risks dropping the trailer.
Question 16 of 20
A sliding-tandem trailer allows you to:
Correct. Sliding tandems shift trailer axles forward (more weight on tractor) or aft (more weight on trailer axles), helping meet axle-weight limits.
Question 17 of 20
When approaching a curve in a tractor-trailer, you should:
Correct. Slow before entering the curve. Once in the curve, accelerate gently to maintain stability. Braking in a curve invites trailer skid or rollover.
Question 18 of 20
When you turn on a tight radius (e.g., into a tight loading dock):
Correct. On a tight radius, off-tracking is more pronounced. Sweep wide enough that the trailer wheels clear curbs and obstacles.
Question 19 of 20
When you are backing a trailer to the right, you should turn the steering wheel:
Correct. When backing, the trailer goes opposite to the way you initially turn the steering wheel. To make the trailer go right (passenger side), start by turning the wheel left.
Question 20 of 20
Off-tracking refers to:
Correct. Off-tracking is the tendency for trailer wheels to follow a smaller-radius path than the tractor wheels through a turn, more pronounced with longer wheelbases.
About the Texas Combination Vehicles exam
Most states administer 20 Combination Vehicles questions and require 80% to pass. The exam emphasizes the unique handling of articulated vehicles: how trailers track behind the tractor, how to prevent rollover, how to manage rearward amplification with multi-trailer combinations, and the correct sequence to couple and uncouple.
The Texas Department of Public Safety Driver License Division follows the federal CDL standards established by FMCSA. To earn the Combination Vehicles 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 Combination Vehicles question bank or browse all Texas CDL practice tests.