NaroEscape

A buddy of mine was telling me that there were a few new GT3's at a recent track weekend, and that they had all gotten new Hoosier R6 (or 7, whatever) tires for their car, but when they went out and started to push the car, it immediately went into 'limp' mode. Something about too much traction or whatever for the computer to be happy?

Needless to say, they were not happy.

Is this true? Are you required to only run the 'street' Michelin Cups?

I'm asking because I was discussing this with one of my friends that owns one and is not on Rennlist, and he was concerned.

What experience do all of you have?

Thanks

Billy Wyatt

R compound is fine but not slicks from what i heard.

shapiroeric

Hoosier are pretty much glorified slicks so really how does the car know the difference?

Petevb

Sounds like a tire diameter issue to me. Do you know what sizes they were running?

MayorAdamWest

I ran hoosiers on the 991S without issue. I can't imagine they'd figure out a way to tell if there was "too much traction"... what if you were just on a stickier surface?

kencollinsjr

there's a warranty void on slicks. has something to do w/ the rear-wheel steering. maybe too much torque for the system. or, maybe it'd just bee too much speed around corners?

orthojoe

This is a very good possibility

NaroEscape

So far, not heard anyone that has run R compounds sucessfully in a GT3??...all just speculation...
don't know sizes, I was not there....but I'll try to find out more info.

So my question then is...has ANYONE run R compound tires on a 991 GT3 without any issues?

tqevo

Hoosier A6's were run without problems as far as I know and they have more grip than the R6's which were designed for longer track sessions.

MaxLTV

Aren't Pilot Sport Cups considered R-compound? If so, then the car is delivered with R-comps to begin with. Anyway, plenty of people drove GT3 on Corsa Rs, which I believe are R-comps. I've seen at least two mentions of using Hoosiers without issues as well.

Petevb

Hoosiers, not sure...
https://rennlist.com/forums/991-gt3/...l#post11649185

There are only a couple Hoosier size combos that give close to the 1.5% rotating speed difference the computer is expecting to see between the front and rear tires. You need to go over an inch smaller and narrower up front, 235-35/ 295-30 combo, to have the best chance of avoiding a confused ecu.

wanna911

Slicks are prohibited on the 991 GT3, Hoosiers were the gray area that no one really knew about. R-compounds like MPCS, R888, Trofeo, NT-01 should not have a problem.

Various tracks provide varying levels of grip. It's conceivable that a Hoosier could pull similar G's to some slicks. I don't think anyone knew the car could tell and go limp mode.

Was there an actual warning indicator that suggested tires were the culprit or did they just assume it was the tires?

Mike in CA

Seems unlikely that the car would go into limp mode based on grip level. Pete's suggestion regarding possible mismatched or incorrect tire diameters makes more sense to me.

usctrojanGT3

+1 the computer doesn't like mismatched tire sizes.

NaroEscape

This is the info I got when I asked what was the problem from a guy close to PCNA:

"Tell him to read the owner's manual, it describes the issue there.
Too much torque on the motors causes them to switch to a Limp-home-mode that takes the dealer to reset."

Not sure I understand? Will probe for more...

But again, all the responses above are speculation and what people "think". What about real world experience?