911vet

Now my tire question becomes: Do I replace my R-compounds with another set, or go to non-R??

I installed my first set of R-compounds (Michelin Pilot Sport Cups) in Columbus, drove to Indianapolis, ran at Putnam. I spun the car once, a friend spun it once (both big spins).

In ONE WEEKEND, I destoryed two tires. One is corded, the other flat spotted. See the pics below.

So my question is: Is it appropriate to replace them with another set of MPSCs given that I have to drive to and from the track?? Or do I abandon this and switch to a set of Dunlop Direzza Sport Z1 Star Specs/Bridgestone RE11?

These were my first R-cmpd and I didn't realize how soft they are. I'm wondering if driving from Columbus to MidOhio and the Bluegrass track later this year is going to chew them up before I even get to the there?

And how easy is it to destroy one with a spin? Geez... I went through $700 in one day. Can't do that again!

Thanks for any advice.

rusnak

That does not look safe to me. Maybe you could find a way to transport the mounted wheel/tires to the track, change them there, and change back to street tires for the drive home? Do rules require a passenger seat to be installed in the car?

911vet

Right - not safe at all.

I could buy a set of wheels and ask a friend to bring them in a trailer, but that isn't the greatest option. Or install a hitch on the 911 and pull a tire trailer. But after spending 2 year's tire budget in one weekend, I don't have money for any of that right now.

Yes, passenger seat required.

pu911rsr

I'd have your alignment checked, looks like you could use some more negative camber. There are a few R compound tires that wear well.
Phil

rusnak

There was an article in Excellence many many years ago about racing Porsches that are driven on the street. I probably gave it away, as I gave most of my Excellence collection away. Anyway, it had pictures of a few 911s and 914s that had tires stuffed into the passenger area, and one guy had a roof rack that he used to haul 4 wheel/tires on to the track. These guys did not trailer their 911s.

http://www.autocrossforum.com/forums...ded&show=&st=&

earlyapex

Why do you need DOT-R tires?

What are your goals on the track and how are the DOT-R tires going to help you get there?

VNTGSPD

I'd like to see pictures of the undamaged parts of the tire, but from what I see, the outer edges look okay. Sure more camber will certainly help, but he damage here appears to be a result of the spins. I high speed spin can damage any tire, especially if you follow the rule of "both feet in" and lock the tires while spinning. "R" tires have very high limits and usually a much less forgiving breakaway tendency than a high performance street tire. So, when the lose grip, they do it quickly.

I don't know about your driving history or am I judging your talent, but it seems like you and your friend may have been overdriving the car. This is a good way to achieve reduced tire wear and lower lap times from my experience. I'd recommend going with the Dunlops as they are affordable and pretty forgiving. They will overheat on hot days or if severly over driven. This could be good though as it will help teach you smoothness. The tire breaks away more slowly as well so you can really feel the limit and use that to practice smoothness.

Driving to events on "R" tires causes virtually NO wear on them unless you are running extreme toe-out settings. I routinely drive to events over 100 miles away on my Kumho V710 which is much softer than a Sport Cup and have experienced no noticeable wear from the commute. I wouldn't use these for daily driving use though.

I'd also heed earlyapex's comments about determining what you want out of a track day and determining whether an expensive "R" tire that may be less forgiving will help accomplish your goal.

Good Luck!

911vet

VNTSGSPD and EARLY APEX: thank your for the very thoughtful responses. I think you're probably correct. On the racing board, the feedback is essentially that I don't have enough negative camber, etc.

But I think the car is probably set up well enough. It's the driver that isn't

I will likely get the Dunlops. Hopefully they don't overheat on me.

g-50cab

Not enough negative camber.

racer

I would also ask if you have done any suspension mods already. I ask, because even if you get, say -2.0 degrees negative camber up front, if the car is at stock ride height and stiffness, there will be a large amount of body lean that will "negate" the impact of your negative camber. If the car was lowered, and stiffened via changes in torsion bars and shocks, then the wear would be reduced as well.

911vet

Lowered. Bilstein HD shocks. Stock t-bars/bushings. Roll bar/tower strut.
Probably won't upgrade the t-bars in this car. I'll wait till I have a full blown track car to do that.

In this case, setup had nothing to do with the tire damage. The damage is focal, not concentric. The damage is from a spin. The spin was purely driver error.

The Michelins were sticking like crazy and all was well until a big, big spin toasted them.

83944

Hey Vet,

Don't feel too bad about the cost/destroyed tyres. Just look at this from another perspective - this is the cost of doing a track day. You were obviously giving the car a bit of stick, something you could not do on public roads. You both learned something and tested your nerve and skills.

It looks like you and your mate had a great day though.

Be pleased and encouraged that your P.car is so well engineered that it can tolerate exuberant driving and you get to do it again and again. I have seen WRX drivers on a track days replace front rotors and trash gearboxes in an effort to outdo a Porsches. A rebuilt WRX gearbox is about $7000 and it will break again!

I track my SC - mostly trailering behind my Cherokee but I also drive it to the track - fang around for the day and then drive it home. The only reason I trailer the car is because I take tools/jack/spare tyres/fuel and usually her ladyship. Can't fit it all in the little car. Often we make it a weekend away.

Possibly your mate can chip in to pay for another set of R-spec tyres.

I would not track a car on road tyres. You will trash them even sooner and the car will handle badly as the tread softens and peels off. Get a second set of 15/16" Fuchs fitted R-spec tyres.

The biggest hurdle to improving your track performance is the driver's ability. Sure spending heaps of $s on suspension/engine/tyres/brakes will get you somewhere but in the end you enter the world of diminishing returns. Do the sensible things by making sure the car is reliable and safe.

In the end it is about enjoying yourself and not trying to out race Mark Webber.

Cheers from down under
Andrew

911vet

Dude - you have restored my faith in humanity!

I agree completely. My home track has many things to hit if you spin. Last weekend, I was at one that has almost nothing to hit. So I pushed to the limits and tried new things. I made a mistake while trying to work on getting back on throttle quicker. A bloody RUF GT3 would have spun doing what I did!

My friend spun out because he was also trying new things, drove two wheels off into mud and grass, and spun re-entering the pavement. The car's alignment and tires were not the issue.

PCA doesn't like to hear it, but I learned as much from my spin as I did from driving. I won't try to explain it all here, but my mistake ingrained a lesson I needed to learn.

$700 in rubber was a small price to pay for the wisdom I took away from the track.

I'm not complaining about the tires. In reality, they were fantastic! Until the damage, they were incredible. And for anyone who thinks the car is soft/poorly cambered/mis-aligned... well maybe. But I was passing, not being passed. And so was my friend in an even more advanced run group.

It isn't a race and it isn't about being the fastest. Like you said, mate, it's "giving the car a bit of stick, something you could not do on public roads. .....testing your nerve and skills."

You said, "It looks like you and your mate had a great day though." WOW, did we ever! And the errors I made resulted in a car off track, scorched rubber, and a better driver.

Thanks. I was getting pretty down with the posts about camber and such here and on the DE/Race Forum. You got me back on track

Amber Gramps

Shannon, how 'bout you just blame it all on me and my goodies. If the Ontario PD can say I "smoked the tires" when I had that box and bypass on my car and the ticket ultimately cost me $700.00 .......then why wouldn't it cost you the same? Sounds logical doesn't it? ....Doesn't it?

...and you wanted to know if I needed a set of tires


I'll shut up now...you have my home address..

(P.S. You're an animal )

Ed Hughes

Yikes. Something wicked seems to be in the mix here. As we discussed previously, maybe it was high pressures, and then an alignment issue. I ran MPSC's full time for two + years. Probably 12-14 track days + 3 or 4 thousand street miles. A couple of spins, a few hot braking episodes. It wasn't until the end on a skidpad that I got cord showing, and it wasn't as bad as what you show.

MPSC's are as good a wearing R compound tire as any I've seen. My only real gripe was getting them to temp. My 2600lb car is borderline on where they are effective. Also, as I pointed out, diligently keeping them under 36psi hot is mandatory for keeping them effective in sticking the car.

These tires are not slouches.