Tief Lernen

I've done three HPDE events at Thunder Hill in my 718 Boxster S (total of 15 sessions of roughly 20 minutes each, 3 separate days total). Started with a brand new set of Pilot Sport 4S's. At the end of the my third day, my front-right tire looked like the attached photo - large chunks of the tread missing around the outer edge.

I was running pressures of about 28-29 cold, usually ending the session between 36 and 38. This seems like an abnormal amount of wear for just three days - right? What should I be doing differently? More pressure, or less? More camber? More track-oriented tires? Or, is this just to be expected?

Pruettfan

The single biggest issue you have is that you're running the wrong tire for track days. The 4s is a great tire for the streets and will perform very well on the track but they won't tolerate the heat that is generated in the sessions. I find them to be the best performance tire available for the street but I don't run them on the track because I don't want my daily use tires getting destroyed by track use. As soon as I committed to regular HPDE days I bought a dedicated set of track wheels and Michelin Cup 2 tires. They hold up well to the demands of the track because of their design, rubber compound etc and the car is happier on sticky rubber. There are several other great options for track tires that can also be used on the road. Camber may be an issue for you also, certainly some negative camber would help spread the load across the tire and would prolong the tire life and improve on track performance. Changing the alignment/camber settings would probably be a good first step.

I am sure some with more Cayman experience can provide some insight that will be more helpful

BillNye

It's a little hard to tell, but it is possible those are pieces of track rubber that have been picked up? What do the other tires look like?
I have 3 days in my 997 running PS4S this year (albeit at an "intermediate" level) and they do not look as bad as yours. My notes indicate I was setting cold pressures to 28F/32R for hot pressures around 36F/40R.

dgmark

Not enough camber, I see the same thing in every late model Porsche that I service that sees track duty. 2.5 degrees
of front camber fixes the problem but only can be achieved by replacing the front control arms with adjustable.

Wild Weasel

I don't know anything about Thunder Hill but I similarly tore up the shoulder of the Goodyear F1's that came on my Boxster after a few days at Mosport.

I was out with a group of people when someone noticed it and said "Hey... I see you've been to Mosport". It was only my front left tire that was trashed.

Different race tracks will wear tires in different ways. You'll need to talk to other regulars there to be sure, but I now swap my tires from side to side after every event to ensure I get the most I can out of them. It's made a big difference.

zedcat

Take a look at the Bridgestone RE-71. It's become one of the most popular street/track tires available currently. And you will need more neg camber. Agree with above post that neg 2.5 is a good compromise but you will likely need adjustable control arms to get there. Suggest as next step, get a good alignment shop to max out the neg camber with stock parts and try a set of RE 71s. Mich Cup 2 is a good tire but more expensive than the RE 71.

Jabs1542

AudiOn19s

More negative camber.

If this is only your 3rd day ever I disagree with a more focused tire, Michelin 4s is perfectly fine for where you are at in the learning curve.

Most people with 3 days won't drive hard enough yet to discover the setup issues with their cars, you have so congrats you're ahead of the curve there but I still don't think you need a more aggressive tire yet. Get an alignment that will keep the tire happy (-2.0 to -2.5 camber) and keep having fun and learning.

Bill Lehman

THIS, I've been tracking the mid-engined platform for 11 years. Shoot for -2.0 R and -2.5 F. You can get close on the rear with the factory adjustments. The front will require aftermarket parts. Camber plates (From Tarett, Rennline, or others) will add at least -1.0 and are less expensive then a GT3 style lower control arm. The RE71 is a decent street/track tire but it won't last long.

Gear Rower

I have no idea of your track/HPDE experience level, but I have seen this type of tire wear after beginners start going a bit faster and adding too much steering input (understeer). Many aren't even aware of this error, believing that they're now "really driving the car". Coming in a bit too hot and then driving the tires beyond their optimum slip angle will very quickly sheer off the outer shoulder. Factory alignments on street cars have inherent understeer, and street tires don't respond well to large slip angles.
I have personally seen one driver who corded the left front edge of his RE71s after 2hrs of driving simply as a result of him overdriving the car and not appreciating the amount of understeer he was creating.

jdistefa

^ This.

Causes:

1. Driver 'error'. Overdriving the tire + too much steering wheel input.
2. Blisters + chunking = too much heat and focused load on the tire edge.
3. Alignment. Need more camber and less toe.

Set the car and driver up better but stay with street tires for now. Learn to drive, slip, rotate, then add more grip.

gbuff

Word, from one who knows......read and heed. Slip angle is your friend. I run RE71Rs on my low-hp fwd car and they are fantastic--all you need until you decide if/when to go to R-comps.

Gary

mannym5

It is definitely a combination of what's written above. Matt and Gear Rower are absolutely correct, BUT the michelin pss and ps4s are also known to have weak shoulders and de-laminating/chunking issues on track when generating heat.
I recently took my m3 street car to a DE day and had it set up with 0 toe and about -1.8f camber and after 3 sessions I started to get similar issues. While the front engine was not helping my case and more camber would have helped, I specifically focused on smooth driving and slowing my entry speed to minimize understeer and overworking the front tires and still started seeing shoulder splitting/chunking patterns form. If you are in need of new tires I would recommend switching to a good street/track capable tire with stronger shoulders like bridgestone s007a, yokohama ad08, nitto nt05, hankook rs4, etc... Bridgestone re71r's perform great but they are very soft/sticky and wont last long.
I also agree that you likely need to alter your driving and improve car setup as noted above. Everything stated will dramatically improve your experience. Good luck!

Glyndellis

I've had a good experience so far with the Hankook RS4 - seem to wear well, and are relatively inexpensive. Maybe not as grippy as RE71, but wear better, therefor liberating more budget for other track days.

YMMMV etc

mglobe