Free, full Tennessee 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.
When checking lighting during a vehicle inspection, which lights must work at all times on a CMV?
B. All marker lights, clearance lights, identification lights, and brake lights — all required lighting must work — Federal regulations require all lights on a CMV to be in proper working order, including required marker lights, clearance lights, identification lights, headlights, brake lights, and turn signals.
CDL safety scenario 8: What is the greatest risk when pulling doubles or triples?
C. Rearward amplification and rollover from quick steering — Rearward amplification and rollover from quick steering. Commercial drivers are expected to manage this situation before it becomes a crash risk. The CDL manual emphasizes controlling the vehicle, inspecting safety-critical systems, and correcting hazards promptly.
A fire extinguisher on a CMV must be:
A. Rated at least 5 B:C and secured in an accessible location — FMCSA requires CMVs to carry a fire extinguisher with a minimum 5 B:C rating, mounted in an accessible location in the cab. B:C ratings cover flammable liquid (B) and electrical (C) fires.
The correct color coding for air brake glad hands (couplings) is:
A. Blue for service brakes, red for emergency (supply) brakes — Air supply (emergency) glad hands are red; service brake glad hands are blue. Cross-connecting them will charge the emergency line with service brake air and disable the trailer brakes.
When coupling a tractor to a trailer, you should position the fifth wheel:
B. Tilted down toward the rear — The fifth wheel should be tilted down toward the rear of the tractor so the trailer kingpin engages properly.
Brake lag in an air brake system is:
A. The time required for air to travel to the brakes — Brake lag is the time (about ½ second) it takes for air to flow through the lines and apply the brakes after you press the pedal.
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.
CDL safety scenario 45: During an en-route inspection, what should you check after the first 50 miles?
D. Cargo securement, tires, brakes, lights, and coupling devices — Cargo securement, tires, brakes, lights, and coupling devices. Commercial drivers are expected to manage this situation before it becomes a crash risk. The CDL manual emphasizes controlling the vehicle, inspecting safety-critical systems, and correcting hazards promptly.
Baffles in a liquid tanker help reduce:
D. Front-to-back surge — Baffles have holes that allow liquid to flow through but reduce front-to-back surge. They don't prevent side-to-side surge.
If you must leave the roadway to avoid a collision, it is better to:
A. Drive onto the shoulder or into an open area — Leaving the road is generally safer than a head-on collision. Steer for an open area. Avoid braking on soft shoulders at high speed.
The Tennessee 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.