BMW 540iA Protection Manual Del Usuario página 19

Run-flat tyre systems
18n
The run-flat distance which can be
covered depends largely on the load
that the vehicle is carrying. With a full
load, this can be 50 kilometres (approx.
30 miles) or less; with an empty vehicle,
over 500 kilometres (approx.
300 miles). Pressure drop on one wheel
of the non-driven front axle and a low
residual air pressure in the defective
tyre considerably increase the run-flat
distance.
Run Flat Indicator
*
As a pressure drop in the tyre is difficult
to detect visually in the case of the two
run-flat systems, BMW vehicles with
run-flat tyers are factory-fitted with a
Run Flat Indicator.
The principle
The Run Flat Indicator monitors the
pressure of all four tyres while the
vehicle is on the move. The system
reports any sudden loss of pressure in
one or more tyres.
In order for the Run Flat Indicator to
"learn" the correct tyre inflation pres-
sure, check the inflation pressure in all
tyres against the inflation pressure table
on page 21 and make corrections as
necessary. Then activate the system.
*
Activating the system
1. Turn the ignition key to position 2
2. Keep the button (arrow) pressed until
the Check Control displays "SET
TYRE PRESSURE" for several
seconds
3. The Run Flat Indicator starts an auto-
matic learning process as the vehicle
is driven, and memorises these refer-
ence pressures. This one-off
"learning" takes at least 10 minutes,
after which the system is able to
detect and indicate a flat tyre.
The same procedure should be
repeated whenever the required tyre
pressures are changed or a new wheel
or tyre fitted.
Online Edition for Part No. 01 49 0 156 444 - © 09/01 BMW AG