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 ...

Notes
The vehicle equipment does not include a spare tire. When using run-flat tires* or tire sealants, a tire does not need to be changed immediately in the event of pressure loss due to a flat tire ...

Opening the main menu
Press the button. The main menu is displayed. All iDrive functions can be called up via the main menu. ...