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kd2789mo
12-14-2005, 06:54 PM
I left the house yesterday, headed to an appointment. About 2 miles from home I got a system chime, an icon in the system check window on the dash (red tire cross-section with a red explanation point inside), the system check below the tach said "Flat Tire!", and a message displayed on the iDrive screen saying, "Flat Tire Warning...the system has detected a flat tire...your vehicle is equipped with run-flat tires....continue driving...maintaining speeds of 50-60mph for a maximum distance of up to 200 miles" (I don't recall the exact wording)

So, I turned around, went back home, and switched cars.

This morning, I checked the air pressure in all the tires. The 2 fronts, and RR were normal, and the LR was at 22psi. There were no changes in the handling characteristics while driving.

I filled the LR to the recommended 42psi, restarted the car, and the system check was clear..."Systems OK"

I just checked the pressure again (about 9 hours later) and it is still at 42psi.
All four tires appeared the same, but then, these tires always look flat.

The car just had its first oil change, at BMW, 2 weeks ago. Presuming they would have check/set the tire pressure...yes...no??

So, I'll check the pressure again in the morning, and if it's still OK, resume driving the car.
Question is, if anyone knows, if the tire was losing air, either way, wouldn't it lose air whether it was sitting in the garage or out driving?

Keith2
12-14-2005, 07:19 PM
20 psi difference is alot. Check the tire very carefully for a nail or screw in the tread. They can be hard to spot. You could also try putting a little dish soap with water in a spray bottle and spraying the tire (tread, bead, valve) any leak will show up as bubbles.

Malibubimmer
12-14-2005, 11:23 PM
I left the house yesterday, headed to an appointment. About 2 miles from home I got a system chime, an icon in the system check window on the dash (red tire cross-section with a red explanation point inside), the system check below the tach said "Flat Tire!", and a message displayed on the iDrive screen saying, "Flat Tire Warning...the system has detected a flat tire...your vehicle is equipped with run-flat tires....continue driving...maintaining speeds of 50-60mph for a maximum distance of up to 200 miles" (I don't recall the exact wording)

So, I turned around, went back home, and switched cars.

This morning, I checked the air pressure in all the tires. The 2 fronts, and RR were normal, and the LR was at 22psi. There were no changes in the handling characteristics while driving.

I filled the LR to the recommended 42psi, restarted the car, and the system check was clear..."Systems OK"

I just checked the pressure again (about 9 hours later) and it is still at 42psi.
All four tires appeared the same, but then, these tires always look flat.

The car just had its first oil change, at BMW, 2 weeks ago. Presuming they would have check/set the tire pressure...yes...no??

So, I'll check the pressure again in the morning, and if it's still OK, resume driving the car.
Question is, if anyone knows, if the tire was losing air, either way, wouldn't it lose air whether it was sitting in the garage or out driving?
20 psi difference is alot. Check the tire very carefully for a nail or screw in the tread. They can be hard to spot. You could also try putting a little dish soap with water in a spray bottle and spraying the tire (tread, bead, valve) any leak will show up as bubbles.

You're dealing with an expensive tire, hard to tell if it's flat. Expensive wheel. Expensive car. And your life. Do you ignore the problem or pretend to deal with it yourself? I don't think so. Take it to a tire specialist and have him check it out. You could have a slow leak from a well-embedded nail or screw, which will only release air sporadically, or when the tire turns at certain angles. In fact, that's probably what it is. If there's a puncture, pray you've caught it before you've compromsied the tire and have to buy a new one. Isn't this common sense? :dunno:

jguadiz
12-16-2005, 01:10 PM
I left the house yesterday, headed to an appointment. About 2 miles from home I got a system chime, an icon in the system check window on the dash (red tire cross-section with a red explanation point inside), the system check below the tach said "Flat Tire!", and a message displayed on the iDrive screen saying, "Flat Tire Warning...the system has detected a flat tire...your vehicle is equipped with run-flat tires....continue driving...maintaining speeds of 50-60mph for a maximum distance of up to 200 miles" (I don't recall the exact wording)

So, I turned around, went back home, and switched cars.

This morning, I checked the air pressure in all the tires. The 2 fronts, and RR were normal, and the LR was at 22psi. There were no changes in the handling characteristics while driving.

I filled the LR to the recommended 42psi, restarted the car, and the system check was clear..."Systems OK"

I just checked the pressure again (about 9 hours later) and it is still at 42psi.
All four tires appeared the same, but then, these tires always look flat.

The car just had its first oil change, at BMW, 2 weeks ago. Presuming they would have check/set the tire pressure...yes...no??

So, I'll check the pressure again in the morning, and if it's still OK, resume driving the car.
Question is, if anyone knows, if the tire was losing air, either way, wouldn't it lose air whether it was sitting in the garage or out driving?

I had the exact same problem and initially took it to a tire shop who told me the tire was fine. I then took it to BMW and they found a bad.......uhhhhhhhhh part? I cant remeber off the top of my head what it was but it was a software issue.

Hope that cleared some of your insecurities.

JC

bimmer7
12-16-2005, 05:31 PM
Take it to the Tire Specialist asap! and check if your tires are damaged in anyway...and if everything is fine there...then take it to BMW for getting the software glitch fixed on your Tire Pressure Monitor.....

kd2789mo
12-17-2005, 10:55 AM
Well....the tire hasn't lost pressure since I filled it on Tuesday.
On Thursday, I took the car to the tire store, they removed the wheel and submerged it under water. They also used some liquid soap (as Kieth had mentioned), but no leaks were detected.
They checked the PSI in all the tires, and I re-initialized the FTM system.

I've come to learn the FTM system on the BMW issues an alert when a "specified" differential is recognized between two tires, LF-RF; LR-RR; LF-LR; RF-RR, based on the pressures learned during the initialization. Though the OM does not specify what that differential is, and the BMW service dept didn't know either.

This is also the reason why the FTM system will not identify which tire caused the alert to be issued.

In this case, the FTM system alerted when the LR tire was at 21 PSI, and the two front tires were at 32 PSI, the LR at 41 PSI. Spec is 32/front, 42/rear, which is the pressures the FTM learned during the its last initialization.

Does anyone know what the FTM system determines as its "specified" differential?

Keith2
12-17-2005, 02:19 PM
I check my tire pressure on my seven every 3-4 weeks. I've noticed maybe a 2 lb difference in the pressures worst case (e.g., one tire will be 2 lbs down, the rest normal), usually they are even. I suggested the soap trick because I like to know the problem before I blindly go to a tire place or a dealer. No clue on the specs for what sets off the monitor.

kd2789mo
12-17-2005, 03:36 PM
I also check the pressure every 3-4 weeks, especially this time of year, as the 7 spends much of the winter months not being driven. We use the Jeep predominantly in the winter months.

The last time the pressure was checked, which may be a poor assumption on my part, was about 4 weeks ago (500 miles ago) when the 7 was at BMW for its first oil change.

As I've found often in the past, most service facilities (even tire shops) "think" there is one pressure specification for almost all vehicles. Seems 32-35 psi is the "standard."

Many facilities look at the side of the tire, and use that as the pressure setting. I've learned the pressure stamped on the tire is the "maximum pressure at maximum load," and rarely does any vehicle carry the maximum load. In fact, most tire applications are fitted well above the maximum load of the vehicle they're fitted on.

My 7 calls for a 10 psi differential between the front and rear tires. I've also found most service facilities put the same pressure in all 4 tires, and have been surprised to learn how few of them know to look at the label (usually on the drivers door jamb) to get the correct pressure.

So, I'm now suspect that during the service at BMW perhaps an error occurred while the pressure was being checked/set in the tires. It's really the only logical explanation why, after a year + in use one of the tires was suddenly 20 psi lower than its ever been.

boston bmw
12-17-2005, 08:11 PM
i just had tires put on my car at the dealership and the flat tire warning came on only minutes after that. they needed to reset it its easy.

dbrh
01-10-2009, 03:06 PM
I have exoerienced similar problems - it only happens when I taken the car to a cold climate such as -6degF. I suspect it is associated with the elasticity of the rubber in the tires - or lack of it - that is causing the problem. A year ago I replaced 2 of the original tires with another make and I still had a problem with the OEM tires.

The pressure slowly decreases as the car is being driven but stays OK when the car is parked (stationary). When the car is driven in warmer climates (above 40degF) the OEM tire pressure remains constant indicating that there is no puncture and yet the SAME tire loses pressure in cold weather. So this is a temperature related phenomenon.