Conventional adjustment of tire pressure

If the "Pressure Loss" fault display appears, tire pressure at the affected wheel must be increased by 0.3 bar or at least to the specified pressure at that wheel. Since diffusion losses are approximately the same at the two wheels on any one axle, the tire pressure at the other wheel should therefore be increased by the same amouint. But do not reduce the tire pressure if too high a value is measured.

The specified tire pressures at 20"C are: front 2.5 bar, rear 3.0 bar {2.5 bar for 17" summer tires)

Note also in this connection that a small amount of air escapes when the pressure gauge is removed from the tire valve. Since the RDK system responds to even slight losses of pressure, this should be taken carefully into account.

Stop the engine while correcting tire pressures, so that the control system can register the new pressure settings.

After the car has been driven for a short distance (at least 20 meters) and has reached a speed above 5 kph, the RDK system will have registered the new tire pressures. If the low pressure warning persists, increase tire pressure further at the affected axle. Repeat this procedure until no further warning is displayed.

However, do not exceed maximum tire pressures of 3.5 bar at the front wheels and 4.0 bar at the rear wheels (3.5 bar for 17" summer tires), since these pressures correspond to tire temperatures which will never be reached in normal driving conditions. Normal conditions basically assume that tire pressures are correct. If a loss of pressure is still shown when 3.5 or 4.0 bar respectively have been reached, the pressure sensing switch must be faulty, a wheel without a pressure sensing switch has been fitted to the car or the pressure sensing switch has become displaced to one side of the HF sensor (see also Page 44 - 26).

To measure and adjust the tire pressure to precisely the correct value (see chart), tire temperature must therefore be known or else the tire pressure must be adjusted accurately with the 9288 system tester. For each 10'C increase in the temperature of the air in the tire, its pressure rises by approx. 0.1 bar. In other words, the correct pressure at any given moment is always higher than the nominal tire pressure once the tire has become hot, and for this reason should never be reduced.

10 20 30 40 50 60 70 00 90 100 °C

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