The concept

The system does not measure the actual inflation pressure in the tires.

It detects a pressure loss in a tire by comparing the rotational speeds of the individual wheels while moving.

In the event of a pressure loss, the diameter and therefore the rotational speed of the corresponding wheel change. This is detected and reported as a flat tire.

    See also:

    System limits
    Sudden tire damage Sudden serious tire damage caused by external influences cannot be indicated in advance.◀ A natural, even pressure loss in all four tires cannot be detected. Therefore, ...

    Safety
    Both the coupe and convertible have front airbags plus side-impact airbags built into the front seats. As required of all 2012 models sold in the U.S., the 640i has standard antilock brakes and an ...

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