BMW 5 Series Grand Turismo 2013 Owner's Manual page 196

Mobility Wheels and tires
Activating/deactivating rear axle
steering
If the status indicating that snow chains are in
use is activated, the rear axle steering is deacti‐
vated automatically.
At speeds above 30 mph/50 km/h, the rear axle
steering is activated again, even though snow
chains are in use.
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