Bad Weather & Night Driving — Idaho
Idaho CDL practice test: 416 free practice questions (Based on the official driver handbook). The official format is not yet verified; check the official site before your test. Bad Weather & Night Driving: 20 questions.
Rain, snow, ice, fog and night driving: visibility, traction and headlight use.
This topic page is still being reviewed against the official handbook. Until review is finished it is hidden from search engines.
| Topic / Metric | Value |
|---|---|
| Topic | Bad Weather & Night Driving |
| License test | Idaho CDL permit (CLP) knowledge tests |
| Topic questions | 20 (5% of 416 total) |
| Review status | This topic page is still being reviewed against the official handbook. Until review is finished it is hidden from search engines. |
Official handbook
Not yet verified
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Questions (20)
1. How much water must be present for a vehicle to hydroplane?
- Usually several inches
- A good amount, such as a large puddle
- A small amount ✓
Answer: C. A small amount
2. You should specifically look out for black ice:
- When it is snowing.
- When the temperature is below freezing and the road looks wet. ✓
- When the temperature is above freezing and there is snow on the ground.
Answer: B. When the temperature is below freezing and the road looks wet.
Look out for black ice when the temperature is below freezing and the road looks wet. The handbook describes black ice as a thin, clear layer that lets you see the road underneath, so the pavement looks wet. It gives a specific warning: any time the temperature is below freezing and the road looks wet, watch for black ice. That matches the condition of below-freezing air plus a wet-looking road, not simply snowfall or above-freezing weather with snow on the ground.
3. When driving under wet conditions, a lack of spray coming from the tires of other vehicles indicates that:
- Ice has formed on the road. ✓
- The pavement is dry.
- The spray is caught on the underside of the vehicle.
Answer: A. Ice has formed on the road.
A lack of spray from other vehicles under wet conditions means ice has formed on the road. The handbook puts this under slippery-surface driving. It says to watch for ice, particularly on bridges and overpasses, and that when other vehicles throw no spray, ice has formed on the road. It also suggests checking your mirrors and wiper blades for ice, since ice there makes an icy road likely. So the missing spray is a warning sign to slow down and treat the surface as slippery, not a sign that the pavement is dry or that spray is trapped underneath.
4. Roads are especially slippery right after it begins to rain because:
- The water mixes with oil and grease on the road. ✓
- Tires are not made to drive in wet weather.
- The water yet hasn't absorbed the dirt and grease.
Answer: A. The water mixes with oil and grease on the road.
Roads are especially slippery right after rain begins because the water mixes with oil and grease left on the road. The handbook says that just after it starts to rain, water mixes with oil left on the road by vehicles, making the road very slippery. If rain continues, it washes the oil away. That oil-and-water film reduces traction, and the handbook notes that slippery roads make stopping take longer and turning harder without skidding. So the first rain is the risky time, before the oil has been washed off.
5. Water that has collected on a roadway can cause:
- Hydroplaning. ✓
- Acceleration.
- Stopping.
Answer: A. Hydroplaning.
Water collected on a roadway can cause hydroplaning. When water or slush collects on the road, the handbook says your vehicle can hydroplane. The tires lose contact with the road and have little or no traction, so you might not be able to steer or brake. Another passage says surfaces where water collects create the conditions for hydroplaning. That matches the answer: the collected water causes hydroplaning.
6. Hydroplaning happens most often when:
- A vehicle is traveling faster than 60 mph.
- Tire pressure is too low. ✓
- Tire tread is too deep.
Answer: B. Tire pressure is too low.
Hydroplaning happens most often when tire pressure is too low. The handbook says low tire pressure makes hydroplaning more likely, and worn tread does too. It explains that tire grooves carry water away, so grooves that are not deep enough do not clear the water well. The same passage also says hydroplaning can happen even at 30 mph when there is a lot of water, so the key setup is low pressure or worn tread, not simply a high speed.
7. Hydroplaning:
- Rarely occurs with large trucks.
- Usually happens when vehicles are traveling faster than 65 mph.
- Can occur with a minimal amount of water on the roadway. ✓
Answer: C. Can occur with a minimal amount of water on the roadway.
Hydroplaning can occur with a minimal amount of water on the roadway. The handbook states that only a small amount of water is needed for hydroplaning, and it points to clear reflections, tire splashes, and raindrops as signs of standing water. It also says hydroplaning can happen at speeds as low as 30 mph when there is a lot of water, and that low tire pressure or worn tread makes it more likely. That supports water amount, not vehicle size or a high speed threshold, as the key condition.
8. When accelerating on a surface with poor traction, such as a wet road, a driver should:
- Speed up quickly.
- Speed up slowly. ✓
- Not be concerned about the pavement.
Answer: B. Speed up slowly.
On a wet or otherwise slippery road, you should speed up slowly. The handbook's advice for slippery surfaces is to drive slowly and smoothly, start gently and slowly, and get a feel for the road before hurrying. It also says to avoid having to slow down and speed up, and to keep a steady speed. On a wet road, those instructions point to easing into acceleration rather than making a quick increase. A slow, gentle speed-up fits the handbook's overall approach to low-traction conditions.
9. If a trailer begins to skid, it is best for the driver to:
- Release the brakes. ✓
- Accelerate.
- Quickly turn the steering wheel in one direction, then in the other.
Answer: A. Release the brakes.
When a trailer begins to skid, release the brakes. The handbook's procedure for stopping a trailer skid is to release the brakes. It explains that the trailer wheel brakes caused the skid, so letting them off lets the tires regain traction. Once the trailer wheels grip again, the trailer follows the tractor and straightens out. The handbook also says to watch the trailer in your mirrors during hard braking, because once it swings out of your lane a jackknife is hard to prevent. That is why getting traction back matters more than braking harder or steering sharply.
10. Driving at night is usually:
- More difficult than driving during the day. ✓
- Simpler than driving during the day.
- Discouraged.
Answer: A. More difficult than driving during the day.
Driving at night is more difficult than driving during the day. The handbook's night driving section treats darkness as a harder condition to drive in. It says your turn signals and brake lights matter even more at night for telling other drivers what you plan to do, and that a clean windshield and clean mirrors matter more than in daytime. The reason it gives is glare: bright lights at night hit dirt on glass or mirrors and block your view. It also warns about glare from oncoming headlights and from your own lights in other drivers' mirrors. All of that adds work and risk that daytime driving does not.
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Last checked: 2026-10-17 · Verified from official source
Updated: · Based on the official driver handbook