When a heavy commercial truck must wade through a flooded road section, what is the maximum safe water depth and the correct driving procedure?

1. Water depth must not exceed the wheel hub center / exhaust pipe height; proceed slowly in low gear at constant throttle, then apply intermittent light braking after exiting to dry the brake linings
2. Water depth may submerge the cab floorboard as long as the truck travels above 40 km/h to push a bow wave
3. Wading depth is unlimited for diesel trucks; driver should shift gears frequently while in the water
4. Drive through in neutral to avoid water entering the clutch housing