so im driving back on the freeway and i start the car to get squirly and i look for the flat tire indicator in the dash and i drive and i got nothing so i think it is just uneven pavement since theres constuction in the area. then it gets worse i cut 4 lanes traffic to get to the right hand shoulder and i get out and the right rear tire is flat. i change to the spare, inspect my tire and i see a 1/4 inch puncture hole in the middle of the tire (not the sidewall) and i tighten up every thing start driving and get the flat tire warning lol..go figure.

hope i can get this puncture plugged i would hate to spend another 30 bux on a rear 20inch tire lol

 

Curious ... Did you ever manually reinitialize the FTM system in iDrive after you put on those different wheels displayed in your pic?

 

Sounds to me like the system was never properly initialized...

 

Actually... -in theory- a change in the circumference of the tire will throw the FTM calculations out of whack. If your aftermarket wheels/tires are different from the spare (which is not only possible but likely) then putting the spare on will trigger the FTM.


With such a low profile on the 20s, a low inflation or flat condition might not alter the collected data enough to trigger FTM.

 

+1.

But the FTM is calculating the rotation speed of tires (diameter).

Just resetting the iDrive should do, if the tire ratio is correct.

 

Either way... one can't change without the other changing (diameter >> circumference).