Huh? The 'Tire Pressure Monitor" system in the X5 does not monitor tire pressure -- it monitors differential rotation between the axles.

IOW it assumes that a tire/wheel that is rotating more slowly than the others is low on air. AFAIK this monitoring is done at the axle not the wheel/tire. That is why the manual tells you to 'initialize' the TPM EVERY time you adjust the air pressure in any tire.

Funf Dreisig

Edit: My Bad I didn't realize that the X5 has TWO systems that monitor low/flat tires. The one I described above is the Flat Tire Monitor system. But there is another more sophisticated Tire Pressure Monitoring system.

Thanks to Penguin and others for pointing this out.