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As air pressure drops, at what range do tractor spring brakes come fully on?

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  1. 60 to 75 psi
  2. 20 to 45 psi
  3. 100 to 125 psi

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References

  1. California Commercial Driver Handbook (DMV) www.dmv.ca.gov/portal/file/california-commercial-driver-handbook-pdf Checked 2026-10-10.

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