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Discussion summary
YOUR RESEARCHSporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Leading reported evidence
Run several different diameter tires
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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Performed · outcome unconfirmed
I have run several different diameter tires on my 986 without issue.
Sporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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Leading evidence: 'Run several different diameter tires' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'abs problem is unrelated' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run completely' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause
I suspect the ABS problem is unrelated to those minor tire differences.
Sporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
unrelated
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause
I suspect the ABS problem is unrelated to those minor tire differences.
Sporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
Run completely
Suggestion or failed attempt
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0
Reported fixes
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Unsuccessful attempts
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Discussions
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Discussions that contain suggestions
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Then on my first run getting on the brakes the first time the ABS kicked in way early blowing my run completely.
Sporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Test "
Suggestion or failed attempt
No successful repair reported for this finding.
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Reported fixes
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Unsuccessful attempts
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Heading to Barber in a few weeks for more "testing".
Sporadic ABS issue with tire diameters? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
986Forum: 1 discussions
0 evidence records excluded for query context · 1 excluded by outcome qualification · 1 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T011819Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
My long awaited RE-71R tire sizes finally came in:
Front: 255/35 - 18 (25" O.D. at 833 revolutions/mile)
Rear: 285/30 - 18 (24.8" O.D. at 841 revolutions/mile)
I have run these same tire sizes and diameters in the past in a ZII tire with no issues, but this time was a bit weird.
First I drove around on the street about 20 miles to scrub them in. After that they threw an ABS code. However, after another 10 miles or so, and shutting off and restarting, the ABS code disappeared, and all seemed well.
The next day, driving to an auto-x event, all was still good with no codes. Then on my first run getting on the brakes the first time the ABS kicked in way early blowing my run completely. After that we did 7 more runs with no problem at all and the brakes were awesome.
However, I'm wondering if this problem may come back sporadically or not. Anyone else ever have an ABS problem like this?
Thanks for any info.
BTW, these Re-71R's are almost as good as a Hoosier - amazing.
Hello.
could you please provide us with the rims dimension for the wheels. I suspect there is a massive difference in wheel circumfence compared to stock (front to back), that would explain the ABS problem (in combination with higher grip values). But i would need the wheel dimensions to calculate that. Also what type and model year is the car?
Thanks & regards, Markus
I have run several different diameter tires on my 986 without issue. On the 987.2 tire diameters are critical to keep the PSM from overreacting.
I suspect the ABS problem is unrelated to those minor tire differences.
I don't have a code reader, so did not obtain any codes.
Yeah, I always heard the same thing about 987 PSM being sensitive to wheel diameters, but never heard anything like this with 986 ABS.
Anyway, the ABS issue went away, and has not come back in any street or auto-x situations since then. Heading to Barber in a few weeks for more "testing".
Thanks for responses.
