I was looking forward to tracking my new Supra at CVR this weekend.
It came with a free track day from NASA. It was a blast driving it at Buttonwillow but I didn't mess with the tire pressures, I just left them at the factory recommended setting for street and track (38 psi cold), I even left the traction control on. At the end of the day, you could tell the tires had been on a track but they didn't show much wear, good to go.
On my Boxster, I normally start the day at 28 to 30 psi square and drop the hot pressure to between 34 and 36 psi hot after each session. The Boxster is fully track prepped with lots of negative camber and I seem to get good grip and wear using that strategy. I carry a new set of tires to every event but if the old tires are still sticky and have some tread left on the edges I don't change them. (200 UTQG cheater tires)
I discovered that the Supra is different. Factory tires are Pilot Super Sports, 300 UTQG and, as previously mentioned, 38 psi.
This weekend I wanted to get a feel for the real cars handling (traction control off) and slowly build up to the limits to see where they are.
I started the first session by dropping 2 psi because I knew the tires would get hot and considered it in the 'safe' initial range and I took the corners at around 75% of what I would normally do in my Boxster. The tires were squealing nicely around 16 but no surprises. After the first session, the tires were hot and at around 45 psi, wear was OK but based on prior experience 45 psi seemed pretty extreme so I dropped them down to 38 (still in the 'safe' range?). Big mistake.
I pushed the car a little harder on the corners during the second session. The car got a little loose on the track out for 10 but I attributed that to being less than smooth on the throttle and it seemed the tires were squealing a bit less on 16 (better grip or just slower?). When I returned from the second session I noticed there was a lot of wear on the drivers side front and I wondered if my tires were going to last the weekend, but the tires were still a few psi above the 'safe' range so I dropped them all down to 38 psi again.
After the third session, the tires were finished and I was done for the weekend. The outside tread on the drivers side front was gone and the tire was chunking, I was worried that I wouldn't make it home without a blowout.
The Vollig crew kindly refilled my tires to factory for the drive home (thanks), they were at 30 front and 32 rear after lunch and the first three run groups in session 4. Gary took a look at my tires and told me that they normally only chunk when they're under-inflated, DOH!
I want to track my Supra again, it was still fun even though I only got 3 sessions, but I learned an important lesson: Ignorance can be expensive.
Maybe next year after I get some new gomme from Bears.