What is the legal minimum air pressure a driver should have before starting a trip in a vehicle with air brakes?

Pick an answer

1. Exactly the pressure at which the low air warning starts to buzz
2. Full operating pressure, well above the level where the low pressure warning would activate
3. Half of the compressor's normal cut-out pressure
4. Any pressure at all, since the low air warning will activate once it's actually needed on the road

Correct!

Not quite. The correct answer is highlighted.