Ouch! those are scary pics! Glad you are safe.
It looks like you have a lot of fun though.
Please keep us informed about what Pirelli says..

 

Thanks man. I have contacted Pirelli...with a link to this thread.


Here are the last 6 minutes of that track day. At 5:45 you can see how I almost left the track under extreme understeer...immediately after you'll hear the thump thump from the rear wheels which were collecting chuncks of shreading rubbers from the fronts. My apologies for a bit of salty language around the 5 minute mark as a guy with a Corvette was getting too close for a timimg session (and would/could not pass in front me).
https://www.dropbox.com/s/x3bkmyz889...t%201.wmv?dl=0

 

It all depends on how much you are into track driving. These would not replace your street tires, they would supplement them. R-Compounds don't 'wear out' as much as they heat cycle out. You only have so many heat-cycles in a competition tire, then they turn blue and lose their grip. A heat cycle is defined as a cold tire warmed up to operating temp then cooled down again. Its a mistake to run them on the street, they don't have good puncture resistance and every drive is a heat cycle, and once shaved there are virtually no rain grooves so they're not very safe or grippy in the wet at all.

You can find a set of 19" take offs from a 997 or 991 for about $ 1,000, especially if they have some road rash on them. Those would be your track tires. 20" wheels are a fashion statement, buy smaller wheels for the track as they are 1) less costly to re-tire 2) give you a lower profile to the track. As long as they can clear the calipers, you're good to go. 18" even better but if you have an "S" they may not clear the front calipers. All the 19" will. Then you buy a set of R-Compounds for the wheels, about $ 1,200. One set should last you a season. You will find they will take the heat from hard-running on the track, tolerate lousy blacktop better than a street tire, and improve your stopping distances considerably because they have far more grip.

If you are doing 5 + track days a year and are a A-level student or better, which you probably are if you are putting that much heat in your Pirellis, you will find it well worth the investment and you will be able to corner without squealing / sliding the tires.

If you don't want to buy R-Compounds buy a second set of takeoff wheels and tires (again 19" or less) with street tires that are half worn or more and run the devil out of them. Full depth 'new' tires squirm more and generate heat, leading to tire degradation, chunking and separation like you experienced. When they cord out, then get another set of half-worn ones, they're cheap. A tire that is worn out for the street at 3/32's makes a pretty good dry-day track tire.

I've had about (25) sets of R-Compounds for my cars over the year. No way I'll run a day on my expensive street tires, you just ruin 'em. A street tire is not designed for track duty any more than a pair of Vice Grips is designed to loosen nuts and bolts. Right tool for the job and all that.

I watched your video - that's like a big auto-x layout, tight turns and left/rights. No wonder your tires fried in that environment. Lots of lateral loads, no where for the tires to cool down on that short straight.

 

drcollie, thanks fo the help. You talked me into it. Here in Arizona there are track days at least twice a month between PCA, NASA, Pro Auto Sports, SCCA, etc... between november and may. Plus we have access to private tracks for a fee. I used to do some open wheel racing with Skip Barber, totally different type of racing, of course (reminds me of Days of Thunder...). My 991 4s is a daily drive for me also. In addition to frying the two front tires I think I also got my rear tires out of balance as I now have failry annoying vibrations I can feel through my seat. I am going to check my force balance on the rears on Wed. I think you are also right on having identified that track as specially hard on the tires. Turns 4,5,6,7,8 are rubber grinders!!

 

Shumi - bet you picked up some rubber on your rears from the track. Just inspect them for lumps on the tread surface and peel 'em off, also check on the inside of the wheels. That's pretty normal to pick up someone else's rubber residue on a track day.

Hey, report back after you try the R-Compounds and let us know. My guess is you will say 'I should have done this a long time ago, so much better". Two quick tip with R's - they won't have the wet grip of your streets so mind carefully in the wet and while they hold the line MUCH MUCH better there is less warning when they let go at max adhesion point, they won't squeal and sing like street tires.

Have fun!

 

Wow, scary, glad everything is ok

 

Seen this with Mich PSS as well on the track with the E92 M3s. A lot of the times you have to make sure you bring the tires to temp before you really push them. My rule for street tires is 8/10s driving, unless you are just ****ting money and don't mind replacing tires after every driving event.

Dave

 

What does not make sense to me is the fact that I was on track with similar cars (M3,Corvettes, Porsche), most with street tires, most with similar times (we were being timed) and no one else had to stop their session for blown front tires....you can blame driving style I guess, but I still think my tires may have failed because they were defective.

 

As usual from Drcollie, this is all extremely good advice (except I don't believe the 991 accepts 18"s). You will also be giggling from the grip the first time you try r-comps.

 

There was a major thread on bimmerpost about this as well, someone tracking their M3 and the Mich PSS literally shredded apart similar to what you got. A lot of this was attributed to driving style and not letting the tires come to temp before really pushing it.

I hope Pirelli warrants the tires for you, but I don't think its going to happen.

Dave

 

Seeking restitution from Pirelli for that tire damage is like removing your lug bolts with a pair of Vice Grips and then asking Porsche to warranty your boogered-up lugs.

Gotta get the right tool for the job.

 

I contacted Pirelli..they want to inspect the tires. The dealer is going to send them back to them.









My new fron tires are causing a steering wheel shimmy. They are perfectly balanced but one of them has a road force of 35lbs. The tech at the dealership tells me that should not be causing vibrations???
This the second time I have replaced tires on brand new 911s. Every time the replacement tires cause vibrations which I did not have on the original tires. I am now convinced Pirelli tires installed at the factory are selected for lowest road force and what we get when we replace them is lower quality tires.

 

Seems to me you should have them look at your wheels and the "roundness" of your tires. Tire belts slip occasionally and cause the tire to go out of round. It will still balance but will produce a shimmy.

With respect to the tire manufacturer, that's a good sign. Pirelli is now in a struggle with Michelin and Michelin is winning the favorite 991 tire battle

 

If the tires are perfectly balanced and the wheels are true and round, you might have something else going on in the front suspension such as a bad ball joint or a control arm bushing. The quick and easy way to eliminate the tire / wheel issue is to find another 991 owner and do a quick swap of front wheels, yours to their car and vice versa. That will tell in in a few minutes if its in your car suspension or the tires/wheels.

Hey, good luck with Pirelli! Maybe they will give you some dollars off or replacement tires as goodwill, doesn't hurt to try.

 

I recently ran 32 psi front and 39 psi rear on a track in my stock TTS. The pressures rose to 45 psi front and 48 psi rear when the stock P-Zeros (~4000 miles) got hot. Man were they squealing away and the fronts became slippery as the contact patches shrank with rising pressure.

Fortunately, my tires did not suffer the same fate as yours! When were your tires manufactured? [sorry if it was mentioned elsewhere in this thread] Mine were made June 2014.