irish guitar

I'm relatively new to tracking, so am seeking input on heat cycles.

I've now run three track days on the Dunlops for a total of 20 sessions and 435 track miles (approximately 20 mins each session, but a few at 30 mins). As of yesterday (day three), the rears didn't inspire any real confidence in their grip and I was constantly lowering pressures to find it. In the last session I started with the rears super-low and they got up to about 33/34 hot. It seemed as if the sidewalls were not happy with such a low pressure, but it did actually give me some more grip until they got to about 33psi.

I'm assuming that these rears have cycled out? For what it's worth, the fronts seem fine, with no perceptible loss of grip.

I'm thinking to go back to the MPSC2, but am also looking at availability of the Pirelli Trofeo R. In reality I'll have to get whatever's available as we're running out of track time here in New England. That was never an issue when I lived in CA [img]graemlins/burnout.gif[/img]

I'm seeking input from those with experience of both track cycles in general, and track cycles of the Dunlops in particular.

Thx,
Viv

carbondan

I am also interested in responses to this question, just subscribing to read what comes through.

GrantG

What do the outer shoulders of the rear tires look like? That's often enough time to wear through the rubber there (wears most quickly there, due to RWS I think) if you've been driving at the limit. Most people I know cord those tires before heat cycles are an issue. If you're a bit slower, then things may be different (being a second or two quicker wears the tires exponentially faster).

irish guitar

Pics attached.

GrantG

You have quite a bit of meat left. If it were me, I wouldn't replace them (even if they're not giving 100% of their original grip, due to heat cycles). If you're not competing, just enjoy them until you need to toss them...

But do be careful not to drive on them hard while they're warming up if you're starting much below 30psi in the rear.

BTW, the part that wears quickest for me in not really seen well in your pics. Try looking from the outside perspective more (the very outside shoulder just before tread ends.

GrantG

Here's how you know they're done (this is with 2.2 degrees neg camber, btw):

irish guitar

Thanks Grant.

I already ordered another set of the Dunlops (heat cycled) from TireRack. The won't arrive until middle of next week, so I'll run the existing tires this weekend and squeeze some more value from them. I was going too try the Trofeos next, but unfortunately I couldn't get the rears until November 18, by which time track will likely be closed.

orthojoe

Happened to see this thread and popping in real quick. I think your problem might be that you are running the pressures too LOW. When I ran these tires I would start out at 27/28 psi cold and aim for 33-34F and 36-38 R hot.
I couldnt say what happens after 20 cycles, so it's possible they could be cycled out as well, but try the higher pressures first before you toss them. When I ran these tires I found them to be very consistent until the outer edges of the rear tires were bald (15 cycles usually)

PS Trofeos suck

carbondan

What cold/target pressures do you run sport cup 2s at?

I've read many different opinions on that questions but I know you've done quite a bit of tire trial and error with GT3s.

Thanks!

orthojoe

It's been long time, so I don't remember exactly. Definitely lower with the cup2. probably 32F/34R hot. Those tires are only fast the first session (faster than dunlop by a few tenths) and the first few laps (3) and just keep dropping after that. Would never run them again. Dunlops are the best tire for the car IMO.

irish guitar

Pics attached showing outside of rear tires.

JesseRohr

Subscribing as my car came with Dunlops.

GrantG

I would definitely keep driving on those

carbondan

2 Questions for the tire whisperers in here:

1. On my .2 GT3 with sport 4s tires, I wore down the outside edge of the passenger front tire first and the inside edge of both front tires started delaminating on my last day. The tires had heat cycled out for sure before that. That last day was a rainy one for them and I wanted to get more experience controling the car with limited grip.
What causes the outside edge of the front tire to wear out? Too little pressure?
Can any instructors watch 2 minutes of this video and provide any pointers to a beginner? Can you see areas where I'm overdriving the tires with too harsh of inputs and offer corrections for me to make?
https://streamable.com/1n612f

2. I'm driving 700 miles to Thunderhill in 2 weeks to do a 2 track days over the course of a weekend, and hopefully will be driving back home on the same set of tires (brand new sport cup 2s that are being installed tomorrow).
The car is at the porsche dealership and running a stock alignment.
Can anyone suggest alignment parameters for my situation? I drive my GT3 to and from work on a more or less daily basis (though cycle through other cars as well). I put on 7k miles in the last year with 6-8 track/autox days and plan to do MANY more this coming season, hopefully every 2 weeks, including several trips of driving the car down to california for a track weekend and back over the winter. I will certainly wear down my tires faster on track than I will on street. How should I best manage that via alignment?

CaymanSinAR

Just want to say I agree with this wholeheartedly.

In June at Barber I was starting my sessions at 29 front and 31 rear. I was finishing around 34/35 front and 38/39 rear. I had absolute confidence from my first hot lap to my last. Just remember to give the Dunlops time to warm up. An extra lap compared to the Sport Cup 2.

The only time I had an issue with the car was one session where a buddy convinced me I needed to start with much lower pressures (because that is what he had to do with Sport Cup 2s). Big mistake. The Sport Maxx Race 2s are not Sport Cup 2s; the Dunlops like high pressures and need more heat. With the lower pressures my rear end was sketchy. After a couple of laps I just decided to take that session easy and focus on proper lines at lower speeds (which is a good thing to do anyway).