See also:

Mercedes-Benz M-Class Owners Manual
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Tire pressure monitor warning messages
If the tire pressure monitor detects a significant pressure loss on one or more tires, a warning message is shown in the multifunction display. A warning tone also sounds and the tire pressure ...

Tires
WARNING   Do not drive with a flat tire. A flat tire affects the ability to steer or brake the vehicle. You may lose control of the vehicle. Continued driving with a flat tire will cause ...