Pass your CDL general knowledge and endorsement tests on the first try. FMCSA-based practice questions covering everything from air brakes to HazMat regulations.
A Commercial Driver's License (CDL) is required to operate large trucks, buses, or vehicles hauling hazardous materials in the United States. The CDL is regulated by the Federal Motor Carrier Safety Administration (FMCSA) and administered by individual states. You must pass written knowledge tests before taking the CDL skills (driving) test.
The CDL general knowledge test has 50 questions covering FMCSA regulations including pre-trip inspection procedures, basic vehicle control, shifting and backing techniques, coupling and uncoupling, space and speed management, and safe driving practices. You must score 80% (40/50) to pass. Additional endorsement tests cover specialized areas like air brakes, combination vehicles, HazMat, tankers, and passenger transport.
PrepTestAI's CDL practice questions are based on FMCSA regulations and include the specific numerical values tested on the CDL knowledge exam — like the 6-foot fall protection threshold for workers around CMVs, air brake pressure ranges (100-125 PSI normal operation), HOS driving limits (11 hours for property carriers), and CDL disqualification offenses.
Our questions cover every topic tested on the CDL Commercial Driver exam:
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Everything you need to know about the CDL Commercial Driver exam:
The CDL general knowledge test has 50 questions. You must answer at least 40 correctly (80%) to pass and receive your Commercial Learner Permit. Each endorsement knowledge test (air brakes, HazMat, combination vehicles, passenger, tanker) has 25-30 questions with an 80% passing score requirement.
If you will operate any vehicle with air brakes, you must pass the air brakes knowledge test. If you fail to get the air brakes endorsement, your CDL will have a restriction preventing you from operating air brake-equipped vehicles. Most commercial trucks have air brakes, so this endorsement is essential for most CDL holders.
Federal regulations require you to hold your Commercial Learner Permit for at least 14 days before you can take the CDL skills (driving) test. During this time you must be accompanied by a qualified CDL holder when operating a CMV on public roads.
CDL drivers must pass a DOT physical examination conducted by a FMCSA-certified medical examiner. The medical certificate is typically valid for 2 years. Certain medical conditions may require more frequent examinations or may disqualify a driver from CDL operation.
A Class A CDL is required for combination vehicles (tractor-trailer) with a GCWR over 26,001 lbs where the towed unit exceeds 10,000 lbs. Class B covers single vehicles over 26,001 lbs or towing a unit under 10,000 lbs. Class C covers vehicles under 26,001 lbs that carry 16+ passengers or HazMat requiring placards.
CDL training programs at truck driving schools typically take 3-7 weeks for full-time programs. After passing your knowledge tests and receiving your CLP, you must hold the permit for at least 14 days before your skills test. Most candidates complete the entire process in 1-3 months.
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