Sporadic ABS issue with tire diameters?

[LAP1DOUG]

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.

[Smallblock454]

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

[thstone]

Originally Posted by LAP1DOUG

First I drove around on the street about 20 miles to scrub them in. After that they threw an ABS code.

What ABS code was reported?

[Topless]

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.

[LAP1DOUG]

Originally Posted by thstone

What ABS code was reported?

I don't have a code reader, so did not obtain any codes.

Originally Posted by Topless

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.

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.

[steved0x]

I wonder if the tire could have rotated on the rim during heavy braking? The computer would probably pick that up as an abs situation?