Chris R.

I had a near catastrophic failure on a left rear this past weekend. E tires had about 10-12 heat cycles and I started to feel the car sliding all over. I was chasing a 997.2RS and pushing hard and chalked it up to wear and heat. Then it got very loose (great drift through 8 at LCMT!) and then I went into the pits. Rear tire was now leaking air badly. Down to 13psi when I checked. The inside of the sidewall was cut (diagonal cuts, about 1cm long all around the tire. No rubbing, lots of clearance and when we took off the tire it was from the inside. The right rear was starting as well. weird.
I'm going to get pics of it and post.
These were not N1 tires but tons of guys I run with use them and have not had any issues.
I am running -2.5 in the back so not a ton of camber, 27's in the back on 18" bbs wheels.
Is it possible it was a bad batch?

RJFabCab

Are you sure you didn't have low pressure or a slow leak to start with?

Cracked wall all the way around sounds like an old tire, a bad batch, or a 'new' tire that sat in your cold basement last winter.

Thank your lucky stars.

Crazy Canuck

Got a pic Chris?

Chris R.

Pressure's were consistent and never below 22psi. I was running them at about 29psi hot and would check them at the end of every run.
Pics now up...

AllanJ

How wide are the rear wheels?

Chris R.

11" I believe.

early_grayce

Do you think this is a similar problem:
https://rennlist.com/forums/porsche-...iredamage.html

Crazy Canuck

Maybe they were damaged trying to keep up with me.

Dwane

Hey there handsome, WTF are you doing with my winter wheels and tires????

Hoosier_Daddy

Hi Chris -- I can only speak from my own personal experience a few years ago with the Michelin slick that ended up looking like yours. It was pretty much determined to be too hard, too early with too low a pressure on a 3200 pound car. In speaking with Michelin, it was suggested I start out at 26-27 with a 3200 pound car and bleed off after the first run. They said there was no harm running higher pressures (vs damaging a tire at too low a pressure) and suggested a hot psi in the 34 range. I was told that all the 30 psi hot pressures are baseline for a 2500 pound car. Once we increased the psi there were no further issues. Hoosier has given me the same advice for their radial slicks... bleed down to 34-36 hot.

Bob Rouleau

I haven't had a problem yet starting MIchelin slicks at 21F 22R cold. Elsewhere there is speculation that excess pressure when mounting the tire can cause a failure like this. Chris, did you check the date code on the tires? Perhaps too old even before mounting?

spare tire

Chris R. Question: Was this failure on your first session of the day? LIke Hoosier Daddy said " too hard too soon" Slicks need more time to get up to temp and pressure. I have friends that I can run with and battle but they can get away from me before my tires are good. R compounds can be warm in one lap or 1/2 lap if it is not the first of the day. Slicks take a little more time before you push them.

997gt3north

I got a ride in a 996cup at WG about 4 years ago and this happened to one of the rears - except far, far worse - it was almost hard to believe there was lots of metal wires poking through. This tire was used for a few runs earlier in the day so it wasn't it's first time out - although it may have been the first run in the afternoon. It happened on the out lap. This was at a Cups & Saucers event in October I believe - good driver, saved it in the Toe and we drove in. At the time, none of the cup guys there had seen anything like it if I recall.

Hoosier_Daddy

I believe I have also had this happen to me, although with a Yokohama slick. The damage was not a split carcass, but rather, one of the belts shifted and/or broke creating what looked like a large bubble on the tread surface. I would never know whether it was excess air or the tire jockey leaning on it with a bar... either way I remember saying to myself "way too much pressure to mount." I think he was up at almost 70 psi IIRC. Bob also mentions age of the tire which I hadn't considered, although a track buddy down here seems to always run rather old (3/4 year) slicks without issue... but his car weighs 2500 pounds...

I still think too hard too fast with heavy cars creates most of the issues we see with slicks.

Rene G

Chris,

glad that you were able to bring the car back in one piece, forget about the slicks and start using the sport cups again, there cheaper and at the end of teh day do you really need the second a lap you get fro mthe slicks.
then I'll have someone to play with!!