All your missed questions are saved
automatically for extra practice.
It's a practice test that's automatically made up of all your missed questions. Once you finish this test, you’ll be able to revisit your Challenge Bank™ to practice and sharpen your skills.
View All PlansAdding difficult questions to Challenge Bank™ is an exclusive Premium feature. Unlock access to 650+ exam-like questions, a Pass Guarantee, personalized study plans, and more.
View All Plans- Updated for March 2025
- Based on 2025 SC commercial driver's license manual
Free South Carolina CDL Air Brakes Test 2025
Our South Carolina DMV CDL Air Brakes Practice Tests are the key to passing your Air Brakes knowledge exam on the first attempt. Failure to pass the South Carolina DMV CDL Air Brakes Knowledge Test means that your CDL will include the restriction “L,” prohibiting you from operating commercial motor vehicles (CMVs) with air brakes. Failing the test in South Carolina also results in a one-day waiting period and a fee should you decide to retake the test. This “L” restriction significantly damages your job prospects in this market.
Because most semi-trucks, tractor-trailers, and commercial buses rely on air brakes for safe navigation, removing the air brake restriction from your CDL is vital for expanded job opportunities. South Carolina features a mix of coastal plains, rolling hills, and the Blue Ridge Mountains as well as urban and rural challenges throughout. Interstate highways like I-26 and I-85 feature hilly and flat regions, where air brakes are essential for vehicle control. Weather in the state brings frequent thunderstorms (especially in the summer) and wintry snow and ice. These impact road conditions and require powerful, reliable braking systems, heightening the demand for air brake-qualified drivers. The major transportation routes include I-26 (connecting Charleston to the western part of the state), I-85 (linking South Carolina with Georgia and North Carolina), I-95 (a vital north-south route), and US-301 (used for regional transport).
The Palmetto State demands air brakes in key industries, including manufacturing (automotive and aerospace), agriculture (poultry and cotton), tourism, and logistics. Companies requiring air brake-qualified drivers include BMW (Spartanburg) and Volvo Cars (Charleston) in the manufacturing sector and Mountaire Farms and Perdue Farms in the agriculture industry. XPO Logistics and Old Dominion Freight Line are major logistics companies with fleets of air brake-equipped vehicles. In the charter bus industry, companies like Greyhound Lines, Southeastern Stages, and Carolina Trailways require air brake-qualified drivers, as do the state’s school districts for their full-size buses (employing hundreds of air brake-qualified drivers).
The written Air Brakes knowledge test features multiple-choice questions based on the state’s CDL manual (South Carolina CDL Handbook 2025) and requires a minimum passing score of 80%. Our CDL Air Brakes Practice Tests mimic the official DMV Air Brakes Knowledge Test and cover everything needed to pass it. The instant feedback you’ll receive on all responses will help you learn faster and ensure you pass the knowledge test!
- Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
- Triple-checked for accuracy
What you need to know
What to expect on the actual SC DMV exam
questions
correct answers to pass
passing score
List of questions (classic view)
- What is the best way to test your vehicle's low air pressure warning signal?
- After the initial drop, the maximum acceptable leakage rates per minute are
- Under which conditions are front wheel brakes good?
- Which of the following is NOT part of the braking process when you're driving a tractor-trailer combination vehicle with an antilock braking system (ABS)?
- If the air tanks are not drained,
- Which of the following can cause brakes to fade or fail?
- Which of the following is NOT part of the air brake system?
- When should you use the parking brake?
- When should you drain your air tanks?
- What is the best way to test if your vehicle's spring brakes come on automatically?
- The tractor protection valve
- How would you check your truck's slack adjusters?
- Why must you pass a knowledge test on air brakes?
- An antilock braking system (ABS)
- Slack adjusters are
- How can you tell if your vehicle is equipped with an antilock braking system (ABS)?
- Which of the following are true about a dual air brake system?
- Which of the following will be true about your brake function if your antilock braking system (ABS) fails?
- Which of the following is NOT part of the drum brake?
- How do brakes work on a long, steep downgrade?
- The purpose of a supply pressure gauge is
- Which of the following should you do before leaving your vehicle unattended?
- Which vehicles must have low air pressure warning signals?
- At what measurement is the safety valve USUALLY set to open?
- Spring brakes are
- The low air pressure warning signal will come on before the pressure in the air tanks falls below
- A low pressure warning signal is required on
- All vehicles equipped with air brakes have
- With air brake-equipped vehicles, the parking brakes should be used
- The use of air brakes on a downgrade is only a supplement to the
- Alabama: Test 1 / Test 2
- Alaska: Test 1 / Test 2
- Arizona: Test 1 / Test 2
- Arkansas: Test 1 / Test 2
- California: Test 1 / Test 2
- Colorado: Test 1 / Test 2
- Connecticut: Test 1 / Test 2
- Delaware: Test 1 / Test 2
- District of Columbia: Test 1 / Test 2
- Florida: Test 1 / Test 2
- Georgia: Test 1 / Test 2
- Hawaii: Test 1 / Test 2
- Idaho: Test 1 / Test 2
- Illinois: Test 1 / Test 2
- Indiana: Test 1 / Test 2
- Iowa: Test 1 / Test 2
- Kansas: Test 1 / Test 2
- Kentucky: Test 1 / Test 2
- Louisiana: Test 1 / Test 2
- Maine: Test 1 / Test 2
- Maryland: Test 1 / Test 2
- Massachusetts: Test 1 / Test 2
- Michigan: Test 1 / Test 2
- Minnesota: Test 1 / Test 2
- Mississippi: Test 1 / Test 2
- Missouri: Test 1 / Test 2
- Montana: Test 1 / Test 2
- Nebraska: Test 1 / Test 2
- Nevada: Test 1 / Test 2
- New Hampshire: Test 1 / Test 2
- New Jersey: Test 1 / Test 2
- New Mexico: Test 1 / Test 2
- New York: Test 1 / Test 2
- North Carolina: Test 1 / Test 2
- North Dakota: Test 1 / Test 2
- Ohio: Test 1 / Test 2
- Oklahoma: Test 1 / Test 2
- Oregon: Test 1 / Test 2
- Pennsylvania: Test 1 / Test 2
- Rhode Island: Test 1 / Test 2
- South Carolina: Test 1 / Test 2
- South Dakota: Test 1 / Test 2
- Tennessee: Test 1 / Test 2
- Texas: Test 1 / Test 2
- Utah: Test 1 / Test 2
- Vermont: Test 1 / Test 2
- Virginia: Test 1 / Test 2
- Washington: Test 1 / Test 2
- West Virginia: Test 1 / Test 2
- Wisconsin: Test 1 / Test 2
- Wyoming: Test 1 / Test 2
Your go-to, trusted source
Experience the Driving-Tests differenceOur commitment to accuracy and quality in our practice tests
Explore our rigorous, multi-tiered verification process that ensures each question mirrors the official manual for unparalleled accuracy.
At Driving-Tests.org, we understand the importance of reliable and accurate practice tests to help you prepare for your DMV exam. That's why we've developed a meticulous process to create and continually update our practice questions, ensuring they reflect the most current driving laws and regulations.
Here's an inside look at how we maintain the highest quality in our practice tests.
Content Creation and Verification Process
- Alignment with Official Manuals:
Every question we develop is based on the most recent version of each state's official driving manual. Our team regularly monitors each state DMV's website for the latest updates to ensure our practice tests are always aligned with the most current information. - Community Feedback Integration:
We leverage feedback from our vast community of users to understand which topics are most frequently tested. This helps us focus on the areas that are most relevant and beneficial for your preparation. - Expert Content Creation:
Our in-house editor, Steven, who has extensive experience in driver education, crafts each question with precision. He conducts a thorough review of each question against the official manuals to ensure accuracy. - Rigorous Review Process:
Once Steven has finalized a set of questions, our team conducts a joint review session. This second level of scrutiny involves content accuracy, proofreading, and fact-checking to eliminate any errors. - User Feedback Mechanism:
After a question goes live on our site, we keep the lines of communication open. Each question features a feedback button, inviting users to report any issues or errors. This continuous feedback loop allows us to address and rectify any concerns promptly. - Responsive Updates:
In line with our commitment to accuracy, we quickly update our practice questions to reflect any changes in the DMV manuals. Additionally, we update the free electronic copy of the state's driver's license manuals on our site, typically within a few days after the DMV publishes them.
Our thorough quality control process ensures that you have access to practice tests that are as accurate and up-to-date as possible. We believe in the power of well-prepared drivers and are dedicated to providing you with the best study tools to help you succeed on your DMV exam.
Pass the First Time – Guaranteed
You’re moments away from your results.
Before you view them, see how 1.15 million drivers used Premium to pass faster.
Real Exam-Like South Carolina Questions
Get all exam-like questions seen on the real test.
99.06% Pass Rate vs. 49% Average
Most Premium users pass on their first try.
Money-Back Guarantee
We stand behind you until you pass.
