[Bandini3]

I thought I would pass along my experience with the TPMS on my 'Canadian' 435Xi coupe.

1. On Day 1, I had driven the car around 400 km, with no issues.
2. The morning of Day 2, I drove the car just 4-5 km before the TPMS gave a warning. The funny thing was, the system indicated pressure issues with ALL FOUR tires. (I have had prior experience with my 535Xi giving a proper warning when a single tire suffered failure at high speed -- the TPMS identified the one tire that had struck an object on the highway).
3. At first, I thought the TPMS warning might have been triggered because the temperature had dropped significantly overnight -- pressure would have dropped ~2-3 psi in all four tires. But that was just a guess.
4. This situation points to the limitations of the 'basic' system, which does not provide pressure readings. Moreover, because of the strong sidewalls of the run-flat tires, it is not that easy to identify an under-inflated tire. All the tires felt as if they were inflated and I could find no cuts or other physical damage to any tire.
5. What to do?
I drove another few km -- I happened to be on a quiet country road. I again stopped on the shoulder and checked all the tires again. At this point, three tires remained cool, but one felt noticeably warmer. I had a problem with ONE rear tire. There was no physical evidence of a problem, although the tire perhaps looked a little low.
6. For some reason, the TPMS had failed to identify the one tire that was under-inflated, although it did warn that "something" was wrong.

The lesson in this? Carry a decent manual pressure gauge in your car. I had one and was able to re-inflate the offending tire and drive slowly while checking regularly to ensure that the pressure never fell below 28/30 psi. I made it home! It would be impossible to do this relying on the 'basic' TPMS, which gives no pressure readings.

It turned out my $400 tire had a small nail in it, but no other damage. It was repairable. My $20 gauge saved the day!

[Photoman]

I have seen this before on my 2012 F30. If you do not immediately stop and reset the Flat Tire Monitor and continue to drive for just a few more kms the initial warning will update and accurately identify the offending tire.

Although the system is "basic" as you put it, it does indeed identify the specific tire.

[Bandini3]

Originally Posted by Photoman

I have seen this before on my 2012 F30. If you do not immediately stop and reset the Flat Tire Monitor and continue to drive for just a few more kms the initial warning will update and accurately identify the offending tire.

Although the system is "basic" as you put it, it does indeed identify the specific tire.

==================
I would guess what you meant to say is "If you IMMEDIATELY STOP and reset ..." [the Canadian TPMS] "... will update and accurately identify the offending tire."

If that is true, it's good to know. But I did not know that at the time and it seems rather odd that the BMW system would force the driver to go through this minor ritual of resetting the device.

I was too preoccupied at the time with the problem and passing traffic to consider playing around with the TPMS. I had already identified the under-inflated tire manually and, at that point, the TPMS wasn't going to help me solve the problem.

Your suggestion might be useful for other Canadian drivers. I would stand by my recommendation that a proper gauge will help deal with situations along these lines.

[Photoman]

Originally Posted by Bandini3

==================
I would guess what you meant to say is "If you IMMEDIATELY STOP and reset ..." [the Canadian TPMS] "... will update and accurately identify the offending tire."

No that's NOT what I said or meant.
FTM's first alert often highlights all four tires... If you kept driving a few more kms the FTM will automatically update and identify the specific tire.

[dalrx]

This exact scenario happened to me past summer...I drove along toward dealer to check issue and within a few km it selected the tire in question after all 4 were showing initially. So pretty good system and cheaper too compared to have all new sensors if you switch out tires .

[Bandini3]

Originally Posted by Photoman

No that's NOT what I said or meant.
FTM's first alert often highlights all four tires... If you kept driving a few more kms the FTM will automatically update and identify the specific tire.

I know what you said -- it's written down.

The description made it sound (to me) as if the F30/32 system's behaviour was counterintuitive -- first it flags all four positions, and then it identifies the particular tire that is giving anomalous readings.

The system on my 535Xi gave a warning within 3-5 seconds and, as I recall, identified the offending tire immediately.

Your suggestion (as I understand it) is that drivers need to give the system a bit of time to complete its calculations and deliberations. I will try to keep that in mind if I encounter another such incident.

[Photoman]

Originally Posted by Bandini3

I know what you said -- it's written down.

The description made it sound (to me) as if the F30/32 system's behaviour was counterintuitive -- first it flags all four positions, and then it identifies the particular tire that is giving anomalous readings.

The system on my 535Xi gave a warning within 3-5 seconds and, as I recall, identified the offending tire immediately.

Your suggestion (as I understand it) is that drivers need to give the system a bit of time to complete its calculations and deliberations. I will try to keep that in mind if I encounter another such incident.

The FTM uses the ABS to monitor therefore it requires the car to be driven for a few kms after cold start, and especially after a tire change in order to correctly pinpoint specific tire(s).

1. First warning highlights there's an issue by indicating all four on screen.
2. Subsequent warning specifies the specific tire(s).

[Bandini3]

Originally Posted by Photoman

The FTM uses the ABS to monitor therefore it requires the car to be driven for a few kms after cold start, and especially after a tire change in order to correctly pinpoint specific tire(s).

1. First warning highlights there's an issue by indicating all four on screen.
2. Subsequent warning specifies the specific tire(s).

I was aware that it uses the ABS system. I haven't looked into the details, but it does beg the question: how can the FTM system "know" there's a problem but NOT know which specific tire is problematic?

Let's assume the system looks for minor discrepancies in rotational speeds (which I think it does). One would think the data indicating any discrepancy would, by definition, also include the fact that such discrepancy was detected either by comparison of the two fronts or two rears, but NOT both.

I admit, that's a bit of an esoteric point.

[giddyup69]

I recently had to patch a tire up. Was driving on hwy to work in morning and got a low air alert.. but only 1 tire. I honestly thought it was just a little low on air. Got to work and of course tire looks fine because of run flat side walls which doesn't help. Took it to a tire shop to double check at lunch time, pressure was under 20 psi and they found a nail which they plugged for me. So not sure why everyone else is getting alerted to all 4 tires at once. Seems strange to me too that it would work that way. But I do agree that without TPMS it's more of a pain to figure out what's going on in the event you get a warming or alert.

[Bandini3]

So, that worked out well for you.

I would maintain that a decent tire gauge is a worthwhile investment, For $20, you can confirm pressures and avoid the risk of ruining a tire (or something worse).

Twenty years ago you could identify an under-inflated tire easily -- visually, or by applying the 'thumb test'. Now that's impossible -- the short sidewall of a 30-series runflat tire won't look or feel that different at 20psi vs 35 psi. That's the basic design goal for an RFT.

[Bandini3]

I had new winter tires installed on my car last week. It just occurred to me that I have no idea if the tire pressures are anywhere near correct.

So, I need to get out that trusty gauge and check the tires myself.

The ABS-linked 'flat-tire warning' confirms that inflation is in some reasonable range, but that's about all.

[Bandini3]

A few days ago, I was just 60km into a 300km highway trip when I got the dreaded "flat tire" warning on my Canadian 435xi's TPMS.

The system flagged all four tires in yellow on the screen and the instrument panel added a further "Flat Tire -- Proceed with Caution" (or something to that effect).

As I've complained before on this thread, the Canadian TPMS does not seem to identify a specific 'problem' tire. That was the case again here.

I slowed down immediately (not a pleasant or particularly safe manoeuvre when traffic is flying by at 125kph) and took an exit a few kms later.

My trusty gauge indicated that the tires were *somewhat* under-inflated and imbalanced front to rear. (I believe ~28psi Front and ~32psi Rear.) I topped then up to around 35psi Front and 38psi Rear.

I checked the pressures at my destination and had no further problems in 500km of driving.

Once again, the $20 tire gauge proved its worth. I'm not sure what BMW drivers do if they get this warning and have no way to check tire pressures.

[CHCCubs]

Originally Posted by Bandini3

Once again, the $20 tire gauge proved its worth. I'm not sure what BMW drivers do if they get this warning and have no way to check tire pressures.

Totally agree with this, IMO everyone should carry a tire pressure gauge in their car. Short of a visible puncture, there really is no way to visually notice a run-flat tire that is low on air without checking with a gauge.