See also:

Tire identification marks
Tire size 255/50 R 19 103 Y 255: nominal width in mm 50: aspect ratio in % R: radial tire code 19: rim diameter in inches 103: load rating, not for ZR tires Y: speed rating, before the R on ZR ...

Switching on/off
Press the button. ...

Tire inflation pressure values over 100 mph/160 km/h
528i Without high-speed tuning feature 550i Without high-speed tuning feature With high-speed tuning feature 528i xDrive Without high-speed tuning feature With high-speed tuning ...