Tire PSI

RyBMW · 09-28-2005, 12:20 AM

I just checked my tire psi and they were all at about 27-29psi. I used a analog tire pressure guage.

How come the tire pressure monitoring system didn't indicate that the pressure is low?
When I add more air to bring the psi up to spec, do I have to update it in the iDrive also?

Barry626 · 09-28-2005, 02:47 AM

If all 4 tires have same psi then car won't tell you.
Yes, if u change air to 32 front & 36 rear for 330i...
you need to update FTM in iDrive.

visor · 09-28-2005, 02:51 AM

1. The TPMS works by monitoring the difference in rotation (therefore, tire circumference) of the front left tire vs the rear right, and the front right vs the rear left, ie. diagonally. Why this way? I don't really know, maybe someone else can answer that. So, if all the tires were to lose pressure at the same rate at the same time, then no alarm would sound. Hmmm, remind me not to drive thru a road that is completely filled with nails....

2. Yes. It may also be on your OBC stalk by the steering wheel.

09-28-2005, 12:20 AM	#1
RyBMW Major 81 Rep 1,038 Posts Drives: X5 Join Date: Jun 2005 Location: NYC iTrader: (1) Garage List 2012 BMW X5 [0.00] 2008 335i [0.00]	Tire PSI I just checked my tire psi and they were all at about 27-29psi. I used a analog tire pressure guage. How come the tire pressure monitoring system didn't indicate that the pressure is low? When I add more air to bring the psi up to spec, do I have to update it in the iDrive also?
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09-28-2005, 02:47 AM	#2
Barry626 Captain 24 Rep 724 Posts Drives: Coming: 2012 135i Join Date: Jun 2005 Location: NY iTrader: (0)	If all 4 tires have same psi then car won't tell you. Yes, if u change air to 32 front & 36 rear for 330i... you need to update FTM in iDrive.
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09-28-2005, 02:51 AM	#3
visor BMW, can I have some LSD please? 91 Rep 1,591 Posts Drives: 2017 F30 340i xDrive Join Date: Jun 2005 Location: Vancouver, Canada iTrader: (0)	1. The TPMS works by monitoring the difference in rotation (therefore, tire circumference) of the front left tire vs the rear right, and the front right vs the rear left, ie. diagonally. Why this way? I don't really know, maybe someone else can answer that. So, if all the tires were to lose pressure at the same rate at the same time, then no alarm would sound. Hmmm, remind me not to drive thru a road that is completely filled with nails.... 2. Yes. It may also be on your OBC stalk by the steering wheel.
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