CDL Practice Test: General Knowledge, Air Brakes & Combination Vehicles
Practice the knowledge areas commercial-driver applicants are expected to understand, get an explanation after each answer in Practice Mode, and see which topics deserve another lap before your state exam.
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What this CDL practice test covers
The tool separates three knowledge areas because they serve different parts of the CDL testing path. General Knowledge covers the broad safe-driving and commercial-vehicle concepts used across CDL classes. Air Brakes covers the systems and inspection knowledge needed to avoid air-brake restrictions when operating applicable vehicles. Combination Vehicles focuses on the additional knowledge used for Class A combination vehicles.
Federal standards, state tests
FMCSA sets minimum federal CDL testing standards, but states develop and administer their own knowledge and skills tests. The federal basic knowledge test must contain at least 30 items, and applicants must answer at least 80 percent correctly. Your state's exact test format and administrative rules can differ, so use your current state CDL manual as the final study reference.
Where ELDT fits
Entry-Level Driver Training is separate from this practice tool. For applicants subject to ELDT, Class A/Class B and applicable passenger or school-bus training must be completed before the state-administered skills test. Hazmat applicants subject to ELDT must complete the required theory training before the Hazmat knowledge test. There is no federal requirement to finish ELDT theory before applying for a CLP.
How to use your results
Don't obsess over one percentage. Use the topic breakdown to find weak concepts, review the explanation and official source, then repeat the module with fresh concepts. A practice score at or above 80 percent is encouraging, but it is not an official passing result and cannot predict exactly what your state's exam will ask.
Official resources
- FMCSA: state CDL testing standards and manual guidance
- FMCSA: how to get a CDL
- FMCSA Training Provider Registry
- FMCSA: state driver licensing agencies
Regulatory and source review: August 12, 2026. Questions were independently reviewed against current official FMCSA, Training Provider Registry, and state CDL-manual sources. This is not an official state exam.
