Tire Pressure Monitoring System

[grease]

Hey Jim,
I am sure there are more accurate ways to measure drop in tire pressure, but BMW has been using this system since 2004 and I don't see any complaints on the BMW forums.

As you suggest this method has many vulnerabilities, even BMW points out some of them. It does compare tires on same axle, various 3 series. 5 series and Z4s have different width tires front to back.

Basically it's purpose is to alert driver to major drop in tire pressure, not necessarily noticeable since many BMWs now use runflats.....