California CDL practice test.
General-knowledge questions from the California Commercial Driver Handbook — air brakes, following distance, cargo securement, and stopping distance.
A commercial driver license (CDL) is generally required to drive a vehicle that:
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California CDL numbers to know
The figures most likely to trip you up on the general-knowledge test — straight from the official handbook.
Safe following distance
- 1 sec / 10 ftBelow 40 mph: 1 second of space for every 10 ft of vehicle length
- +1 secOver 40 mph: add 1 second (a 40-ft vehicle = 4 sec, or 5 sec over 40 mph)
Total stopping distance @ 55 mph
- 142 ftPerception distance
- 61 ftReaction distance
- 216 ftBraking distance
- ≈419 ftTotal — about the length of a football field
Speed, reaction & weight
- ¾–1 secAverage driver reaction time
- 4×Double your speed (20→40 mph) → braking distance ~4× longer
- 9×Triple your speed (20→60 mph) → ~9× longer
- Empty = longerEmpty trucks need a GREATER stopping distance (less traction)
Tire tread minimums
- 4/32 inMinimum tread depth on steering (front) tires
- 2/32 inMinimum tread depth on all other tires
Figures from the official California DMV handbooks (dmv.ca.gov). Always confirm current requirements with the DMV.
Common questions
What does the California CDL general-knowledge test cover?
Vehicle inspection, basic vehicle control, shifting, communicating and seeing, space and stopping distance, and cargo safety. Our practice questions are based on the public California Commercial Driver Handbook.
Which CDL test is this for?
This is the general-knowledge test required for every California commercial driver license. Endorsement tests — air brakes, combination vehicles, hazmat, passenger, tanker — are separate, and the class you need (A, B, or C) depends on the vehicle.
Is this CDL practice test free?
Yes — you get free practice rounds with instant explanations. Unlimited CDL practice, smart review, and the timed exam simulator are part of CDL Pro.
How many attempts do I get on the CDL knowledge test?
Three per test — fail the same test three times and your application becomes invalid, so practice before you go.
Can I practice in my language?
PassGolden is built for the languages the California Driver Handbook is published in — English, Spanish, Chinese, Vietnamese, Russian, Punjabi, Hindi, and Armenian.
New to the CDL process? Read California CDL: classes, permit & general knowledge test.