CONTINENTAL EXTREMECONTACT SPORT XL

Ouch. Halfway through a great day (90 minutes of track time) at Palm Beach International Raceway. So question is crappy tires, crappy car setup or crappy driver?

 

Those tires are not meant to handle track duty

 

Looks like the car has a lot of toe out on it. Just looked at the tire spec not a good one for the track at all. That is hard road course Robert

 

looks like not enough camber should be about 1* min for track

 

Welcome to the club. As stated, you need a track alignment. The GS can easily melt the stock pilots if driven hard, even with an alignment.

 

More negative camber would have helped.

It also looks like you started with too much tread on them.

You can run street(ish) tires on the track, but they need to be almost worn out. If there's more than 3/32 to 4/32 of tread depth left, the tread squirm overheats the tread blocks, and they melt and pull off in chunks. The result looks just like your picture. It's counter-intuitive, but if you're going to run inappropriate (street) tires on a road course, they last much longer if you shave them down to 3/32 tread than they do if you leave them with more tread.

 

Thanks! Never thought of it like that.

 

The main problem was insufficient negative camber which let the tires roll over onto the edge and wear it out. Even with -2.0 degrees camber you may not have enough with some tires. Could also had excessive toe in which turns the outside edge of the tire forward causing it to wear prematurely.

Bill

 

Just to be clear. With a better alignment, the missing chunks would be distributed evenly across the face of the thing. You'd have chunks missing on the inner edges and even in the center of the tread.

The alignment caused the uneven distribution of the missing chunks.

The fact that chunks pulled off at all is because the tread was too deep, and the tire was driven dangerously overheated.

I say that from experience back in the days before there were "DOT rated race tires," when "Showroom stock" and "Improved Touring" race cars in SCCA ran on shaved street tires. If you failed to shave the tires, or didn't shave them enough, you got missing chunks like that regardless of your alignment. A good alignment would make the missing chunks come off from all parts of the tread instead of just one edge.

 

ehhh... A local at my track has ran 6 track days on these exact same tires just fine. He's a fast driver too.

Yep. Not enough camber. Look at that wear mark, the tire letters were touching the track surface. What was your hot tire pressure?

 

You said it yourself, back in the days. Tires nowadays are better. Summer tires can be run on the track without shaving. The stock MPSS ZP can run hard track days just fine straight from the show room, yeah they will wear but not chunk off.

 

New tires or heat cycled a few times?

 

That is over heating... what PSI were you running? Could also benefit from alignment.

 

Those are Continentals, not Michelins. Continental definitely recommends shaving their tires if you're going to use them competitively. They come out of the mold at 10/32", but should be shaved for competition use. I think the recommended depth is either 5/32 or 6/32 for racing. Actually, the latest generation ExtremeContact DW and ExtremeContact DWS tires have letters molded into the tread. If you're running on a dry track, you shave off the depth of the "W" letters (which are shallower than the "D" letters molded in the tread). When only the "D" remains, it's good for a dry track.

I'm pretty sure that Michelin still recommends shaving their Pilot Super Sports as well if you're going to use them competitively. I asked about that when we put Michelins on the C6 last year. I think the recommendation was that for track use, shave them to 6/32" or less. They also come out of the mold at 10/32".

One more thing, the track he was at, Palm Beach International Raceway, was one of the hardest on tires of the places I've run in the southeast. There are some very long turns there, and some very high speed turns as well. If you're having tire overheating issues at all, that's a track where it will be a problem.

 

These aren't Mazda Miatas. They are heavy, powerful, have massive brakes and giant tires to go along with great (for what it is) suspension. You can't just throw street tires and street brake pads at them while driving them to their high capabilities and expect them to last.

Get track tires and pads.

 

Mine chunked off. So did my cup2.

 

1) negative camber (track alignment)
2) better tire for track
3) not related but if you havent done track alignment then you likely haven't done brake pad/fluid upgrades. Get those.

 

The biggest thing with "track tires" is preparation. That matters more than getting outright "race compound" tires.

Race compound tires generally come molded with a tread depth of 4/32nds to maybe 6/32nds. They are much less likely to overheat because of that. The compound is softer, which gives more grip. If the tread was deeper, those would overheat as bad or worse than full tread depth street tires.

Running a "street tire" that's been shaved down to 4/32nds to 6/32nds won't be as grippy as a full race compound, and it won't be quite as fast, but it also won't overheat like the tires shown in the opening post. For tracks where the surface is "hard on tires", less tread depth actually lasts slightly longer. For Palm Beach International, I'd run 4/32nds of tread and no more.

Street tires are less expensive and more cost effective for track days, provided you have them properly prepared (shaved). In all honesty, you can learn some things better on a more slippery tire than you can on the outright fastest and grippiest race rubber available.

 

So what PSI is recommended for track days?

 

32 hot