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Missouri driving lesson · Safe Driving Basics

Carbon monoxide, deer and tire care

A 3-minute lesson from the Missouri course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.

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Read time
3 minutes
Course unit
Safe Driving Basics
Checkpoint questions
4
Source pages
61, 62

Some everyday hazards are easy to overlook: an invisible exhaust gas, deer on the road, and worn or underinflated tires. A few simple habits protect you from all three.

Carbon monoxide

A deadly gas given off by vehicle motors.

Handbook p. 61 ↗

To avoid carbon monoxide poisoning, don't:

  • Leave the motor running in a garage
  • Leave the motor running with the windows closed when you park
  • Use the heater or air conditioner in a parked vehicle with the windows closed
  • Leave the vents open when following closely behind another vehicle
  • Drive with a defective muffler or exhaust system
Handbook p. 61 ↗

Deer crash facts:

  • Be especially alert where deer crossing signs are posted
  • Deer seldom travel alone; if you see one, others are likely nearby
  • Deer gather around fields, streams and gardens
  • Most deer crashes occur in January, May, and October through December
  • Highest risk: sunset to midnight, and the hours shortly before and after sunrise
Handbook p. 61 ↗

Know the rule

After dark, use high beams when there's no opposing traffic. They light up deer's eyes and give you more reaction time.

Handbook p. 61 ↗

Know the rule

If a deer crash is unavoidable, don't swerve. Swerving off the road or into oncoming traffic can increase the risk of injury.

Handbook p. 62 ↗

Know the rule

Check that no one is behind you before slowing suddenly. Too much brake pressure can drop the front end, so the deer's body comes into the passenger compartment.

Handbook p. 62 ↗

After a deer crash:

  • Report it to a local law enforcement agency
  • Get a police report, if required, to file an insurance claim
  • Tell a local Missouri Department of Conservation agent where it happened
Handbook p. 62 ↗

Know the rule

Check tire pressure with a gauge against the recommended PSI in your owner's manual or on the driver's door jamb. Let air out or add air until it matches.

Handbook p. 62 ↗

Penny test for tread depth (monthly or before a long trip):

  • Hold a penny by Abraham Lincoln's body between your thumb and forefinger
  • Put Lincoln's head into a groove where the tread looks lowest
  • If any part of his head is covered by tread, you have a safe amount
  • Below that (about 2/32 of an inch), grip in bad conditions is greatly reduced
Handbook p. 62 ↗

Put it into practice

At dusk in November you see a deer cross the road ahead. Check your mirror, slow down, and expect more deer to follow. If a crash can't be avoided, stay in your lane rather than swerving.

Check your understanding

Read the question, decide on an answer, then open it to check the explanation. These are Roadwise study questions based on the source handbook.

Which time of day is one of the highest-risk periods for deer-vehicle crashes?
  1. Noon to 3 p.m.
  2. Sunset to midnight
  3. Midnight to 3 a.m.
  4. Mid-morning rush hour

Answer: Sunset to midnight

The highest-risk periods are sunset to midnight and the hours shortly before and after sunrise.

Handbook p. 61 ↗
A crash with a deer is unavoidable. What does the handbook advise?
  1. Swerve onto the shoulder
  2. Do not swerve
  3. Swerve toward the center line
  4. Steer off the road and brake

Answer: Do not swerve

Swerving off the road or into oncoming traffic can increase the risk of injury, so don't swerve.

Handbook p. 62 ↗
Using the penny test, when do your tires have a safe amount of tread?
  1. When all of Lincoln's head shows
  2. When the penny drops fully into the groove
  3. When tread covers part of Lincoln's head
  4. When tread is below 2/32 of an inch

Answer: When tread covers part of Lincoln's head

Place Lincoln's head into a groove; if any part of his head is covered by tread, you have a safe amount.

Handbook p. 62 ↗
To avoid carbon monoxide poisoning, you should not leave the vents open when following closely behind another vehicle.
  1. True
  2. False

Answer: True

Leaving vents open while following closely is on the guide's list of things to avoid to prevent carbon monoxide poisoning.

Handbook p. 61 ↗
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