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Discussion Starter #1
Long story short put my 2000 E39 M5 back on the road couple weekends ago.

On hard driving involving corners I've had a "tire defect" warning pop up on the dash. Each time I've pulled over to check all four tires including tire pressure - everything's fine. Had the issue checked out by my mechanic and found the warning is not a TPM (which I know the car doesn't have) but a combination of the other systems.

Anybody else had this or have any info?
 

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Unlike more modern systems, our tire monitoring system doesn’t check or know the tire pressure. Instead it calculates the tire circumference by the number of rotations compared to the other tires and looking for irregularities, not sure if it backs into the diameter from there or what

First thing I would do after confirming correct tire pressures would be to reset the system. And then see if it comes back on again. Since it’s using tire circumference (and maybe diameter) another thing to check is to see if the tires are worn evenly


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Discussion Starter #4
No ABS or DSC warnings or lights.
 

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Discussion Starter #6
No codes.

Tried pressing the tire control button (to right of steering wheel, on the trim) and it shows "Tire Control Inactive" on my dash.

Wondering if this was disabled at the dealer, similar to how they can disable backseat side impact airbags if you've got kids' seats back there.
 

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Discussion Starter #8
Thanks for the link.

I'd checked that over but no luck.

Tire pressure is factory and there's next to no wear and definitely no bulges as tires are near new.
 

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If you have INPA or ISTA/D you could test your wheel speeds etc. but at this point probably the most practical thing would be put in a new or used RPA aka RDC module. It's worth opening up your old one to look for corrosion. Might be salvageable.
 

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Discussion Starter #10
Thinking, would a hard turn dramatically shifting the car cause enough loss of friction tire to ground to change the rotational speed measurement? Now remembering how hard I've been taking turns, the answer maybe 'yes'.

Gonna drop in at the dealer where I know the service manager to see if he's got any advice.


...it calculates the tire circumference by the number of rotations compared to the other tires and looking for irregularities...
 

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I've been receiving this warning since I purchased my M5 2 years ago. It happens on every single drive and to be honest, it's a PITA. It locks you out of the OBC/Cluster.

I haven't noticed anything wrong with my tires...premature wear, the vehicle is out of balance, etc. It's possible my RDC module is bad...but I coded "Tyre Defect" out with PA Soft because it was cheap and easy.
 

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Thinking, would a hard turn dramatically shifting the car cause enough loss of friction tire to ground to change the rotational speed measurement? Now remembering how hard I've been taking turns, the answer maybe 'yes'.

Gonna drop in at the dealer where I know the service manager to see if he's got any advice.
Not likely. There are members here, including myself, who have beat the piss out of their M5s at the track and likely taken tighter corners faster than you’re doing on the street (I hope!) and every time I get the Tire Defect one of my tires is low or all of them are. I fill it up, good to go.
 

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Discussion Starter #13
Checked tire pressure at cold yesterday. All four tires at spec, confirmed with door tag and two gauges. Maybe I am taking corners faster than at the track 😬
 

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No codes.

Tried pressing the tire control button (to right of steering wheel, on the trim) and it shows "Tire Control Inactive" on my dash.

Wondering if this was disabled at the dealer, similar to how they can disable backseat side impact airbags if you've got kids' seats back there.
That "Tire Control Inactive" message has to be part of the problem. I've never seen that one pop up. I have had occasional false tire inflation message in the M5 over the past 15 years, but maybe twice...vs. about 5 times in my Z4M coupe since 2007.
 

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Checked tire pressure at cold yesterday. All four tires at spec, confirmed with door tag and two gauges. Maybe I am taking corners faster than at the track 😬
That tag, very poorly formatted. Just for the sake of clarity what are your pressures? Will your system enter re-calibrate mode? Does it complete recalibration?
 

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I got the message a couple of weeks ago. Tires looked OK, but there was a screw in one back tire and it had a very slow leak. So system worked just as designed. That said I've had the false warning a few times over the years, but always went away so didn't work about it. GL diagnosing.
 

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Discussion Starter #17
Couple of us inspected the tires and found no issue. They're near new, btw. When the warning comes up I find a place to pull over and restart the car - warning doesn't reappear.
 
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