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AhaBulb: Stuff Everyone Should Know · ahabulb.com/cdl-following-distance-40ft-55

For a 40-foot vehicle at 55 mph, what following distance should you leave?

Leave about 5 seconds.

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  1. 2 seconds
  2. 4 seconds
  3. 5 seconds ✔

Why: Four seconds for the 40-foot length, plus one second because the speed is over 40 mph.

Huh, didn't know that: When the road is slippery, you need even more space to stop.

The dad joke
What is a truck's favorite dance move? The five-second rule.
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References

Answer: 5 seconds. Four seconds for the 40-foot length, plus one second because the speed is over 40 mph.

  1. California Commercial Driver Handbook (AAMVA model manual) www.dmv.ca.gov/portal/file/california-commercial-driver-handbook-pdf
    Over 40 mph, you would need 5 seconds for a 40-foot vehicle and 7 seconds for a 60-foot vehicle.
    Checked 2026-10-11.

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