California CDL — General Knowledge practice
California CDL — General Knowledge: Traffic Laws practice test
Speed limits, turning and signaling rules, headlight and seat-belt requirements, and the everyday laws every driver must follow.
Content reviewed against official driver handbooks · August 12, 2026
10 questions · pass with 8 correct. You get instant feedback and an explanation after every answer.
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Study questions with answers
10 sample Traffic Laws questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. Outside a business or residence district you want to overtake a vehicle crawling up a grade at less than 20 mph. What does the law require?
Correct answer: You must be able to pass at least 10 mph faster and finish within a quarter of a mile
Two conditions apply at once: your speed advantage has to be at least 10 mph, and the whole maneuver has to be finished inside a quarter of a mile. If you cannot satisfy both, stay behind.
Source: California Commercial Driver Handbook — Driving Safely (Controlling Your Speed)
2. Several large trucks are traveling together as a caravan on an open highway. How much room must be left between them?
Correct answer: At least 100 feet, so other traffic can move past one truck at a time
When heavy vehicles run as a group on the open road, state law calls for a minimum 100-foot gap. That space gives a passing motorist somewhere to pull in instead of having to clear the whole convoy in one move.
Source: California Commercial Driver Handbook — Driving Safely (Controlling Your Speed)
3. Apart from the hours around darkness, when else does California law oblige you to switch your headlights on?
Correct answer: Any time weather has forced you to run the windshield wipers
Headlights are mandatory from a half hour after sundown until a half hour before sunrise, any time rain, snow, or fog has you running the wipers, and any time you cannot clearly make out a person or a vehicle a thousand feet away.
Source: California Commercial Driver Handbook — Driving Safely (Night Driving)
4. Measured up from the road surface the vehicle stands on, what is the general height limit for a vehicle and its load in California?
Correct answer: 14 feet
The standard ceiling is 14 feet from pavement to the top of the load. A double deck bus is allowed a few inches more, and farm equipment moved incidentally along a highway is treated separately.
Source: California Commercial Driver Handbook — Other CDL Rules (State Laws and Rules)
5. In California, what is the highest speed limit that applies to a truck tractor built with three or more axles?
Correct answer: 55 mph
State law caps several classes of heavy vehicle at 55 mph. The list takes in a truck or truck tractor with three or more axles, any vehicle towing another, and a school bus carrying pupils.
Source: California Commercial Driver Handbook — Other CDL Rules (State Laws and Rules)
6. Which statement about speed limits for commercial vehicles is correct?
Correct answer: Never drive faster than is safe, and obey limits that may be lower for trucks
You must never drive faster than is safe for the conditions, and you must obey posted limits, which may be lower for trucks than for cars. Conditions such as rain, curves, or heavy traffic may require an even slower speed.
Source: California CDL Manual — Section 2: Driving Safely (Controlling Your Speed)
7. Under federal rules, how may a commercial driver legally use a mobile phone while driving?
Correct answer: Hands-free only, without holding, reaching for, or dialing a handheld phone
Federal law allows only hands-free use with the phone within easy reach; holding the phone, dialing more than a single button, or reaching for it in an unsafe spot is banned. Texting while driving a commercial vehicle is also prohibited.
Source: California Commercial Driver Handbook — Driver Disqualifications
8. On an undivided open highway outside any business district, how close may you follow a school bus that is carrying pupils?
Correct answer: No nearer than 300 feet
California sets a 300-foot minimum behind certain vehicles, among them a loaded school bus, a rig with three or more axles, and anything hauling explosives. The rule lifts while you overtake, where each direction has two or more lanes, and inside business or residence districts.
Source: California Commercial Driver Handbook — Driving Safely (Controlling Your Speed)
9. Is it lawful in California to drive at night with only your parking lights burning?
Correct answer: No — they are allowed as signals, or alongside lit headlamps, but not on their own
No vehicle may be operated on parking lights alone. They are legal as signals, or when the headlamps are lit as well, but never as your only source of light.
Source: California Commercial Driver Handbook — Driving Safely (Night Driving)
10. At what point must you drop your high beams for a vehicle coming toward you or for one you are following?
Correct answer: Once you are within 500 feet of it
Five hundred feet is the trigger in both directions, approaching oncoming traffic and closing on a vehicle ahead. Beyond that range high beams are the better choice, because they reveal far more of the road.
Source: California Commercial Driver Handbook — Driving Safely (Night Driving)
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California Practice Test Pack — 2026 Printable Edition
$4.99 · One-time purchase. Instant download.
Our own printable edition — nobody paid us to show it to you, and everything in it is free to read here too.