2008 Mercedes S-Class Owner's Manual - Page 566

Operation Tires and wheels Run Flat Indicator (Canada only) While the vehicle is being driven, the Run Flat Indicator monitors the set tire inflation pressures by evaluating each wheel's rotational speed. This allows the system to detect a significant loss of pressure in a tire. If a wheel's rotational speed changes due to falling tire inflation pressure, you will see a corresponding warning message in the multifunction display. The Run Flat Indicator may function in a restricted manner or with a delay if: snow chains are mounted to the vehicle in presence of ice and snow you are driving on a loose surface (e.g. sand or gravel) you are driving in a very sporty manner (involving rapid acceleration or high speeds in curves) Warning! G Warning! G When the multifunction display shows the message "Tire pressure Check tires", one or more of your tires is significantly under-inflated. You should stop and check your tires as soon as possible, and inflate them to the proper tire inflation pressure as indicated on the vehicle's tire information placard. Driving on a significantly underinflated tire causes the tire to overheat and can lead to tire failure. Underinflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability. Each tire, including the spare, should be checked monthly when cold and set to the tire inflation pressure recommended by the vehicle manufacturer on the vehicle placard or the tire inflation pressure label. The Run Flat Indicator does not provide a warning for wrongly selected tire inflation pressures. Always adjust tire inflation pressure according to the placard on the driver's door B-pillar or fuel filler flap. The Run Flat Indicator does not replace regular checks of the tire inflation pressures since a gradual pressure loss in more than one tire cannot be detected by the Run Flat Indicator. The Run Flat Indicator is not able to issue a warning due to a sudden dramatic loss of tire inflation pressure (e.g. tire blowout caused by a foreign object). In this case bring the vehicle to a halt by carefully applying the brakes and avoiding abrupt steering maneuvers. 565