The flat tire monitor on our `06 530xi has never worked correctly. I'm an IT professional with a penchant for reading the manual and doing things as instructed. I initialized the FTM per the instructions. We had a flat tire on the interstate with no indication from the system. After I put on the space-saver spare, the indicator came on. After getting the tire repaired, and reinitializing the FTM, the system later told me that I had a flat tire when I didn't. That last time, a semi had several tires explode when we were alongside. There was a terrific explosion and smoke. It rocked the car, but there was no damage to the tires. Does the FTM monitor sound also? How could I have a flat (down to the rim) at highway speed without triggering an alert?