The car was towed from the scene to BMW I did not get the chance to measure it. BMW are still investigating and I’m waiting for word from them. 5 days ago the South African BMW guy says they have deferred it to Germany. But it’s coming up to a month and I’m still waiting
If the pressure in the spare were low, I guess it could reduce the effective diameter enough to cause the ABS to kick in. Keep us informed…
I love your “biscuit wheel” for what we call “donut spare.”
;-]
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The OP already stated twice that he was on a motorway (expressway) and did not have a gauge to check the tires so how could he check the spare?
This leads me to a pet peeve with my 2012 Camry. To check the air in my spare, I have to remove two floor mats. a fiberboard panel, a stiff foam tool and jack holder, take the tire out of its well and turn it upside down to check the pressure. Then it has to be installed upside down again or nothing else would fit back in.
This is idiotic design. This spare, actually all spares, should be on the tire pressure monitoring system.
Even if it were, you would still have to go thru those convolutions to add air as needed.
Some of them are…I actually thought some of the Toyota models included the spares on the TPMS
Wouldn’t work for me, since my TPMS has been tango-uniform for over a year. I just carry a good 12V compressor (with gauge) with me and don’t worry about it.
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hmmm … if so that seems a problem with the BMW design. The brake rotor shouldn’t melt down just because a tire is low on pressure. The ABS computer should be able to figure out how much braking it is doing, and place limits to prevent the brakes overheating. It seems like if the ABS computer knows it has to continually apply the brakes to one wheel, it would indicate a major problem and that would completely disable the ABS component and turn the ABS dash light on.
I don’t think that’s what’s happening here. I’m expecting it will turn out that the brake caliper was damaged by the flat or the tire change. Or it just failed for unknown reasons, and flat tire involvement is just a co-incidence. Hopefully OP will keep us informed what BMW determines.
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The spare in my jeep is installed upside-down too. Moronic.
For what it’s worth, I overinflate my spare tire, knowing that I can easily let air out if necessary when it’s put on.
That seems to be SOP, nowadays.
The only reason that I can think of is that it allows for a much shorter bolt to cinch the tire down to the floor, but I suppose that there could be other reasons.
My theory is that it reduces the possibility of valve stem damage if things are stored in the spare tire area.
OP says they stopped to check tires and than reset monitor? Nothing changed. He did not add air. How could he reset the system if 1 tire was still low? My car has to be manually reset after I add air to a low tire. The system does not reset automatically. The fact that it alerted driver to a still low air pressure situation after he started driving again may be how it works?
That is another possibility, I suppose.
Don’t understand what you mean. Why would it matter which way the spare tire lays?
George, it was in commiseration with Oldtimer’s comment. With the spare tire upside down in its bay, the valve stem points down. You have to completely unbolt and remove the jack and wrench, and then flip the tire over, just to check the tire pressure. Then you get to put it all back together again.
The hold-down threaded rod isn’t long enough if the valve points up.
ok, I see what you mean there. Good point.
Did I ever mention I wasn’t mechanically inclined? … lol …
So BMW have gone to Germany and now come back saying they will cover all costs. They will repair the rear left upgrade the DSC software then put spare on right wheel to try reproduce failure. (Not sure if I like this plan).
They said the spare wheel was at 1.5bar. So was low but a not flat
Thanks for letting us know. I am glad they are covering repair cost but it doesn’t do much for your peace of mind. Insightful’s idea of carrying a small 12v compressor seems like a good Idea.
Someone asked why it matters that the spare isn’t on the tpms since I would still have to go through the trouble of removing it anyway. I would not have to go through the trouble of doing all that just to find out the pressure was ok.
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What is the correct pressure for your spare? It is probably much higher than the running tires, which should be about 2 bar.