Yannick-HST

Hey Folks.

One of my friends has a very strange problem with his 2008 Cup and the Michelins on the car.

The car is completely stock except some softer Öhlins shocks. Wheel-sizes are the original ones used on the 2008 and the tires are those marked as "Porsche Cup" tires.

Right now, it´s already the 4th (!) tire on the left rear on this car, the metal-weaving comes out of the inside of the tire. The tire was used on our 2008 without any issues! But after having it for 2.5 h on this car for some trackday-driving (not very hard, just some smooth laps at Spa) it starts to let the weaving grow out of the rubber. Same with all the other tires...

No issues with rain-tires... Just with the slicks. And they were mounted by the same Michelin Race-Service that also installed our tires.

As I already said, he had this problem with another 3 Michelin slicks on the left rear! Always the same...

Will post a pic later!

Does anybody know this? Was it propably an error in the production process? If so, why does this only habben on this car and not on our 2008? He´s pissed of buying a new set of rear tires all day and throwing others with 85% away...

Greetings
Yannick

Yannick-HST

Photo attached...

ZSA Motorsport

if my eyes are seeing it right, lookst o be the inside of the tire of the tire side wall.
its ithere something on the fender lining, the spring perch, springs, etc. that it might be rubbing every so slightly or that might be protruding out a smidge and under heavy load it its just scraping into the sidewall a bit??

Yannick-HST

Yes. It´s the inner side wall...

That was one of the first things i was looking for... but I was unable to find anything which has the possibility to touch the tire...

You also can´t see any damage or rubbing points on the tire...

ZSA Motorsport

contact Eric @ jackson motorsport group. they are a sponsor of the PCA club racing, and they are a great group of folk.
if they dont ahve some ideas, at minimum, they can forward the photos and details to the michelin techs.

to me, that situation would need to be resolved before id go about driving more on it. if its the same batch of tires, maybe its just tire specific. not assuring when doing cup car speeds on a track.

Yannick-HST

That´s for sure...

I´ll e-Mail Michelin directly and I´ll also give the boys in Weissach a call... It seems like nobody heard of this before...

coryf

This happens to michelins when they are driven with low tire pressure. Normally around the paddock or storage with 15 psi or lower pressure. The banked track rear tire was really bad about this. A lot of negative camber will make it more sensitive to this as well. We have seen this a lot.

Yannick-HST

Thanks!

Talked to the Michelin Distributor for racing-tires in Germany and he told me the same... Happens also if you hit too many Kerbs in the warm-up lap or if you drive it too hard while the tire isn´t on temperature yet.

PedroNole

Ditto! I've had it happen on 2-3 tires over the past couple of years.

Jim Sullivan

I've had a Michelin blowout.. tore up the fender well, ruined a wheel. Wires were showing on inner wall of the tire. I've seen this with others as well, left rear always.

People were suggesting that you put high pressures in and come in every couple laps and bleed pressures down. Concerned with this procedure, I was told by a pro GT racer that pros go out at low pressures as normal, but stay off the curbs for a couple laps.

So the Michelin is the fastest tire, but personally I think it's unacceptable for them to put this flawed product out.

ngoldrich

As another data point -

I have never run my Michelins below 23 psi cold and up to 30 psi hot.

I have never had this problem in 4 years of running Michelins.

I had the exact same thing just happen at the NASA Nationals on 3 sets of rear tires. It was always the left rear.

None of them had ever been run low pressure.

I am very rigorous about this.

Before I even load the car on the trailer, I trailer at 30 psi.

Michelin at the track told me it was because the tires were older - even though they were this seasons tires......

1 of the 3 left rears would not hold air any more as so many belts had punctured the inner side sidewall.

Yannick-HST

Thanks for the Input!

Same thing happened again last tuesday in Spa... Pressure was 2.1 bars (about 30 psi) hot.

Dumb question: Does the same thing also happen on Yokohamas for example? What tires are also good ones for running them on a ´08 Cup?

jrgordonsenior

Great point about running higher pressures when trailering. It also helps with clearance, I use 35 lbs....

Whomever said that to you should be embarassed....

jrgordonsenior

I've never heard or seen that happen with Yokes and most cups and GT cars run them out here because of their generous contingency.....

Yannick-HST

Guess we´ll give the Yokos a try...

Thanks for the info!