Texas CDL Combination Vehicles Practice Test

The Texas CDL Combination Vehicles test is a multiple-choice knowledge test you take for your commercial learner's permit. Texas Department of Public Safety (DPS), Driver License Division says you need 80% to pass (source).

Last updated Oct 7, 2026. FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC.

By Scott Wilder, Editor

Last reviewed against the Texas CDL manual on October 7, 2026

Scott Wilder on X | scottwilderhq.com

FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC. It offers free exam-style practice tests built from the official CDL manual. FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.

Texas CDL permit facts

What	What Texas says	Source
Combination Vehicles pass mark	80%	Official page
CLP fee	$25 (expires 180 days from issue)	Official page
CLP validity	180 days, or until your Texas driver license expires, whichever is first	Official page
CLP holding period	Hold the CLP at least 14 days before the skills test	Official page
Knowledge test retest rule	After a failed test, your application stays active for 90 days. After 90 days or three failed attempts, whichever comes first, you must submit a new application, pay fees again and retest	Official page
Test languages	All CDL and CLP knowledge exams are English only since June 1, 2026. Spanish tests are no longer offered and interpreters are not allowed. Skills tests are English only. Drivers who cannot show enough English are not eligible for a Texas CDL or CLP.	Official page

20 question Combination Vehicles practice test

1. What is a "bobtail" in trucking?
1. A. A tractor without a semitrailer
2. B. A trailer with a short body
3. C. A tractor pulling a single empty trailer
4. D. A straight truck with a dump body
Show answer
Answer: A. A tractor without a semitrailer
The manual defines bobtail tractors as tractors without semitrailers.
From the official CDL manual, section 6.1.3.
2. In Step 9 of coupling, what do you do to lock the trailer brakes?
1. A. Push in the "air supply" knob
2. B. Pull out the "air supply" knob
3. C. Put the transmission in neutral
4. D. Raise the landing gear
Show answer
Answer: B. Pull out the "air supply" knob
Pulling out the "air supply" knob locks the trailer brakes.
From the official CDL manual, section 6.4.1.
3. In Step 11, how far do you raise the landing gear to test the connection?
1. A. All the way up
2. B. Not at all
3. C. Halfway up the legs
4. D. Slightly off the ground
Show answer
Answer: D. Slightly off the ground
Step 11 says to raise the trailer landing gear slightly off the ground.
From the official CDL manual, section 6.4.1.
4. During the air flow check, what do you use to provide air to the service line?
1. A. The red trailer air supply knob
2. B. The tractor parking brake
3. C. The trailer handbrake
Show answer
Answer: C. The trailer handbrake
The trailer handbrake provides air to the service line.
From the official CDL manual, section 6.5.2.
5. What should you see on the landing gear during the walk-around?
1. A. Half raised so it clears the ground
2. B. Lowered with the crank removed
3. C. Raised, with the crank handle left on the ground
4. D. Fully raised, undamaged, with the crank handle in place and secured
Show answer
Answer: D. Fully raised, undamaged, with the crank handle in place and secured
This is what the manual lists for the landing gear.
From the official CDL manual, section 6.5.1.
6. You do not hear air escaping from both lines at the rear. What should you check?
1. A. That the trailer wheels are chocked
2. B. That the shut-off valves on the trailers and dollies are open
3. C. That the landing gear is raised
4. D. That the trailer tires are fully inflated
Show answer
Answer: B. That the shut-off valves on the trailers and dollies are open
Closed valves block the air from reaching the back.
From the official CDL manual, section 6.5.2.
7. At about what air pressure does the tractor protection valve close automatically?
1. A. 5 to 15 psi
2. B. 60 to 80 psi
3. C. 20 to 45 psi
4. D. 90 to 100 psi
Show answer
Answer: C. 20 to 45 psi
The manual gives a range of 20 to 45 psi.
From the official CDL manual, section 6.2.2.
8. An older trailer has no spring brakes, and its air-lines are crossed. What is the danger?
1. A. You could drive away with no trailer brakes
2. B. The trailer parking brakes will lock up and hold the rig
3. C. The trailer wheels will lock and drag
4. D. The tractor air tanks will fill too fast
Show answer
Answer: A. You could drive away with no trailer brakes
On such a trailer, the wheels turn freely and you would not have trailer brakes.
From the official CDL manual, section 6.2.5.
9. During the walk-around, what should you check about the air lines at the glad hands?
1. A. They are hanging down to the ground
2. B. They are tight with no slack at all
3. C. They are secured with enough slack for turns
Show answer
Answer: C. They are secured with enough slack for turns
Air lines must be properly secured with enough slack for turns.
From the official CDL manual, section 6.5.1.
10. You pile more cargo on a truck. What happens to its center of gravity?
1. A. It moves higher, which makes the truck steadier
2. B. It moves lower because of the extra weight
3. C. It moves higher, so the truck turns over more easily
4. D. It stays the same if the cargo is tied down
Show answer
Answer: C. It moves higher, so the truck turns over more easily
A higher center of gravity makes the truck easier to turn over.
From the official CDL manual, section 6.1.1.
11. How should the trailer height compare with the fifth wheel when you back under?
1. A. High enough that the tractor does not touch it
2. B. Level with the fifth wheel plate
3. C. As high as the landing gear will go
4. D. Low enough that the tractor raises it slightly
Show answer
Answer: D. Low enough that the tractor raises it slightly
The trailer should be raised slightly by the tractor as you back under.
From the official CDL manual, section 6.4.1.
12. You push in the trailer air supply control, but the spring brakes stay on. What should you check?
1. A. The ABS lamp bulb
2. B. The air-line connections
3. C. The fifth wheel grease
4. D. The trailer tires for proper inflation
Show answer
Answer: B. The air-line connections
The manual says to check the air-line connections if the spring brakes will not release.
From the official CDL manual, section 6.2.5.
13. Where are shut-off valves (cut-out cocks) found?
1. A. At the back of trailers used to tow other trailers
2. B. Next to the tractor's glad hands only
3. C. Inside the cab on the dash
4. D. On each trailer air tank
Show answer
Answer: A. At the back of trailers used to tow other trailers
They are in the service and supply air-lines there.
From the official CDL manual, section 6.2.7.
14. In a rig with several trailers, whose rear wheels off-track the most in a turn?
1. A. The last trailer
2. B. The tractor's rear wheels
3. C. The first trailer's rear wheels
4. D. All units off-track by the same amount
Show answer
Answer: A. The last trailer
The rear wheels of the last trailer off-track the most.
From the official CDL manual, section 6.1.6.
15. When does ABS activate?
1. A. Every time you touch the brake pedal
2. B. Only when wheels are about to lock up
3. C. Only at speeds above 40 mph
4. D. Only when the trailer is empty
Show answer
Answer: B. Only when wheels are about to lock up
ABS adds to your normal brakes and acts only at impending lockup.
From the official CDL manual, section 6.3.2.
16. When you couple a gooseneck hitch, what do you remember about safety chains?
1. A. They are optional for short trips
2. B. They are needed only for loaded trailers
3. C. All trailers are required by law to have them
4. D. They replace the clamp latch
Show answer
Answer: C. All trailers are required by law to have them
The manual says all trailers are required by law to have safety chains.
From the official CDL manual, section 6.4.7.
17. Why should you allow lots of following distance in a combination rig?
1. A. So you can pass more easily
2. B. So the trailer brakes stay cool
3. C. So the load stays centered
4. D. So you can brake early
Show answer
Answer: D. So you can brake early
Extra distance and looking far ahead let you brake early instead of making a panic stop.
From the official CDL manual, section 6.1.3.
18. When the full weight of the trailer is on the tractor, what clearance do you check at the trailer nose?
1. A. Between the top of the tractor tires and the nose of the trailer
2. B. Between the kingpin and the cab roof
3. C. Between the trailer tires and the landing gear
4. D. Between the glad hands and the bumper
Show answer
Answer: A. Between the top of the tractor tires and the nose of the trailer
You check clearance between the top of the tractor tires and the trailer nose.
From the official CDL manual, section 6.4.1.
19. What tends to happen when the wheels of a trailer lock up?
1. A. The trailer lifts off the road
2. B. The trailer follows the tractor straight
3. C. The trailer tends to swing around
Show answer
Answer: C. The trailer tends to swing around
Locked trailer wheels make the trailer swing around, which is a trailer jackknife.
From the official CDL manual, section 6.1.5.
20. When uncoupling, when should you chock the trailer wheels?
1. A. Only when the trailer is loaded
2. B. If the trailer has no spring brakes, or you are not sure
3. C. Never, because the landing gear holds it
4. D. Only on a downgrade
Show answer
Answer: B. If the trailer has no spring brakes, or you are not sure
Air could leak out of the tank, releasing emergency brakes.
From the official CDL manual, section 6.4.2.

Texas CDL Combination Vehicles questions

What score do you need to pass the Texas CDL Combination Vehicles test?

Texas says you need 80% to pass the Combination Vehicles test.

Is the Texas CDL Combination Vehicles test the same as other states?

The Combination Vehicles test is built on the same federal knowledge standards in every state, so the topics match the CDL manual. Texas uses its own handbook: https://www.dps.texas.gov/internetforms/Forms/DL-7C.pdf

How much does a CDL permit cost in Texas?

CLP fee: $25 (expires 180 days from issue).

What languages is the Texas CDL knowledge test offered in?

All CDL and CLP knowledge exams are English only since June 1, 2026. Spanish tests are no longer offered and interpreters are not allowed. Skills tests are English only. Drivers who cannot show enough English are not eligible for a Texas CDL or CLP.

Sources

https://www.dps.texas.gov/internetforms/Forms/DL-7C.pdf
https://www.dps.texas.gov/section/driver-license/driver-license-fees
https://www.dps.texas.gov/section/driver-license/how-do-i-apply-commercial-driver-license
Manual sections used in this test: 6.1.1; 6.1.3; 6.1.5; 6.1.6; 6.2.2; 6.2.5; 6.2.7; 6.3.2; 6.4.1; 6.4.2; 6.4.7; 6.5.1; 6.5.2

Combination Vehicles practice test in nearby states