See also:

Inflating the collapsible spare wheel
WARNING Inflate the collapsible spare wheel only after the wheel is properly attached. Inflate the collapsible spare wheel using the tire inflation compressor before lowering the vehicle. ...

Kilopascal (kPa)
Metric unit for tire pressure. 6.9 kPa is the equivalent of 1 psi. Another unit for tire pressure is bar. There are 100 kilopascals (kPa) to 1 bar. ...

Please bear the following in mind
At the onset of winter, have your vehicle winterproofed at a qualified specialist workshop, e.g. at an authorized Mercedes- Benz Center. Observe the notes in the "Changing a wheel" ...