Two718s

Kind of a new guy to this whole motorsport thing, so please forgive my ignorance...

A couple days ago, my wife and I took our nearly-new 718s (base Boxster and Cayman S) to Sonoma Raceway for Level 1 of an HPDE course. It was great fun, and we learned a lot. However after a morning of autocross followed by 40 full laps of the racetrack (I put 80 miles on the odometer, purely on the track), I was slightly horrified at what the heat did to the rear tires (Michelin Pilot Sport 4s) on our Cayman S. While the front tires look OK, the rear ones -- with only 2K miles since new -- both appear to have a line of melted rubber near the outermost tread. Additionally, if you look closely you'll see a few thumbnail-sized pieces of melted rubber stuck on other parts of the tires.

See pics attached. My question is:

1) Is this normal after such usage? Of course I knew that a track session would chew up a fair bit of useful life of the tires, but the melted rubber was not something I expected.

2) Are these tires safe to drive? The car feels normal, but I'm wondering about the long-term effect of that band of melted rubber.

Sorry for the dumb question...

loneregister

Looks like happy tires to me!

Scooby921

Nothing wrong with those tires. Your first two pics show that you actually picked up rubber off the racing surface. That's extra, not some being melted off your own! It'll wear off and disappear. No worries. The last pic looks like normal wear after a track day. You're pushing the car hard and leaning on the shoulders in the corners. This is what rubber abrasion looks like. It also looks like you weren't quite rolling the tire to the shoulder. You could let a few psi out of the tire and find a bit more grip on the track. There should be several little arrows ^ on the shoulder of the tire indicating maximum recommended rolling of the tire. Adjust tire pressure so you get to this point and don't exceed (much). Tire pressure will then need to be adjusted as you get better and driving and extracting performance from the car. Higher speeds = higher loads = more rolling of the tire and may need higher pressures (and a better alignment if that time ever comes).

Two718s

Thank you, all! That's very helpful. Much appreciated, and quite a relief.

I didn't adjust the pressures during the session...I had them set to factory settings before the day, and they're still right on those settings. What do you all do in terms of adjustments pre-event and during the track sessions?

LexVan

Looks like you picked up race rubber, to raise the car slightly, to pass post-race tech inspection.

eltoshan

tires look fine, plenty of street and track life left in them.

Two718s

Yes, that was exactly my intent

The one thing that surprised me was the G-meter on the Cayman S. Prior to the HPDE event, I had achieved 1.21G's (left), 1.17Gs (right), .95G (braking,) .91G (acceleration) After the event I was surprised to see that I'd only bumped up the 1.17 to 1.19 (right) and the .95G to 1.0G (braking.) I guess that means one of two things: 1) I need to chill the heck out on the backroads, or 2) I need to do another event and push harder on the track

eltoshan

Peak g forces can be misleading, a banked turn can add a significant amount to the peak readings. For example I can max out at 1.5g laterally and 1.4g braking at my local track with a 5-10 degree banking. That said, probably not the greatest idea to get even close to the limit of traction on the streets.

brad@tirerack.com

I would agree with the rest of the responses. Looks like OPR (other peoples rubber) and the tires are fine.

Gofishracing

The feathering on the fronts are from pushing thru the turns.

LexVan

You can generate some pretty good G-force numbers going through the Starbucks drive thru lane. Caffeine is very inspirational.

David993S

No no no. It looks like the tires got too hot, started to catch on fire and the rubber started to melt...……...



Just messin' with ya 718. The tires look just like they should after a little track time. Lots of track life left.

MattUF

Tires aren't toast, but your wallet may be...HPDE can be a slippery slope

Two718s

True!! Between the $1K for two course slots, $1K for track insurance, plus the gas, tire, and brake wear on 2 cars, I don't even want to know how much we spent. But it was fun and very educational.

Made me want to pick up a $10K 986 Boxster just for the track. And so it begins...

Unseelhilr8

Tires look fine and a lot of track and street life left in them.