Free, full California CDL general knowledge test practice right here in your browser — real exam format (50 questions, 80% to pass), diagnostic and adaptive modes, spaced-repetition review, and a readiness dashboard. No signup, no paywall — your progress is saved automatically on this device.
After taking a 34-hour restart, a property-carrying driver:
A. Resets their 60/70-hour clock to zero and can start a fresh cycle — A 34-hour restart (34 consecutive off-duty hours) resets the driver's 60/70-hour cumulative clock to zero, allowing them to begin a fresh cycle. It must include two consecutive periods from 1–5 a.m.
During the engine compartment check, you should verify the alternator belt is:
C. Not cracked, frayed, or too loose/tight — Check the alternator/serpentine belt for cracks, fraying, and proper tension. A broken belt causes charging and cooling system failure.
If you become stranded in severe winter weather, you should:
C. Stay with your vehicle and call for help — Stay with your vehicle — it provides shelter. Run the engine sparingly for heat with a window cracked for ventilation. Call for help.
When using a fire extinguisher on a vehicle fire, you should aim:
B. At the base of the fire, staying as far back as the extinguisher allows — Aiming at the base of the fire and staying back puts out the source while keeping you clear of heat, smoke, and flare-ups.
When must a CDL holder report a traffic conviction in another state to their employer?
B. Within 30 days of the conviction — A CDL holder must notify their employer of any traffic conviction (in any vehicle, in any state) within 30 days of the conviction, as required by 49 CFR 383.31.
What is the primary reason you must stop at railroad crossings when hauling a tank vehicle with flammable liquid, even if not placarded?
B. Federal regulations require all tank vehicles carrying flammable liquids in quantities that require a placard (and some that do not) to stop at railroad crossings — Tank vehicles hauling flammable liquids — including when loaded in amounts requiring placards — must stop at railroad crossings per 49 CFR 392.10. The combination of flammable liquid and a train collision risk makes this mandatory.
What is the maximum legal gross vehicle weight (GVW) for most combination vehicles operating on federal highways without special permits?
B. 80,000 lbs — The Federal Bridge Formula limits most combination vehicles to a maximum gross vehicle weight of 80,000 lbs on the Interstate Highway System without special permits.
Under HOS rules, after 8 consecutive hours of driving, you must take a break of at least:
D. 30 minutes — After accumulating 8 hours of driving, federal HOS rules require at least a 30-minute off-duty break before driving again. The break can be taken as a sleeper berth period. Skipping it extends fatigue and violates regulations that can result in an out-of-service order.
A bus driver's number one responsibility is:
D. The safety of the passengers — Passenger safety comes before schedule or any other duty, since the driver is responsible for everyone aboard the bus.
Air brakes use _____ to make the brakes work:
A. Compressed air — Air brakes use compressed air to push brake pads against brake drums or discs to slow/stop the vehicle.
The California CDL general knowledge test has 50 questions, and you need 80% to pass — at least 40 correct answers. The practice tests on this page use the same format. The 80% passing score is a federal FMCSA standard used by every state.
80%. You can miss at most 10 of the 50 questions. The readiness dashboard on this page tracks whether you're consistently scoring above that bar.
Yes. Every practice test on this page and everything in the DMVPrep iPhone app is free — no ads, no paywall, no account.
Federal motor carrier safety regulations (FMCSA) — the same rules every state's CDL exam is drawn from. Every question in the DMVPrep app cites the regulation or handbook section it comes from.
Yes — the DMVPrep app includes all 3,745+ questions in Spanish, and the whole app works in Spanish.