Those of you that have tracked your GT3's early in their life, have you had any problems with the full tread depth PS2's chunking because of the heat?Thanks.

 

No. The PS2 N2 is the best street tire I have ever used on the track. No chunking but I only did a couple of days with them. I ran them at 40 lbs hot all around. They are not as good as an R compund tire but for street rubber - I was impressed.

 

No problems @ 38 front and 45 rear, hot.

 

No problems, 38f-40r hot, 3,600 miles including 6 track days = 1,000 track miles

 

No problems and good performance here too. I ran around 38/40 pressures. Started at 40/40 but the fronts seemed to work better with a little less.

 

At what mileage did you put the tires on the track? I will have maybe 600 miles on them before tracking them. I was thinking that them being at full tread depth could cause some trouble.

 

T-J

I had about 1000 miles - break in essentially. No issues. With stock alignment you will wear the shoulders though. Tire pressure should be in the 38-40 hot range. New tires will squirm more and increase heat and pressure rapidly. Plan to stop mid session to check hot pressures and bleed down to 38 F and 40 R or 40 all around depending on the rest of your set up. At over 40 hot the back end feels loose on my car(s). Tire engineers have told me that street radials are designed to work best at 40 lbs hot pressure. Porsche suggests 44 lbs on the low profile tires to protect the rim and avoid pinch flats caused by pot holes. Use the 38/40 hot on track then add air for the drive home. No potholes on any racetracks I like!

Lynn try 40 hot in back. I think you will like it better.

Rgds,

 

Why do you say break in is essential? Just to get all of the mold releasing agent off? Or for other reasons? Thanks.

 

I had it on the track around 750 miles - took it fairly easy on the engine and drive train until I got over 1k though.

I don't think Bob was saying break-in is essential - he said essentially - meaning he essentially just had break-in miles on the tires before tracking.

 

BOB-D your interpretation is correct. I ran on the street tires during break in and a few track day afterwards. Around 1500 miles I switched to R compounds.

Rgds

 

I can second Bob_R's comments on the MPS2 pressures, as once the rear builds up to around 44 you will notice the car will feel less settled. Nothing horrible, but when you take it back down to 40 you'll see the difference.

My experience so far has been that starting at 34f 36r cold is very good, within 5 mins you are up to temp, but if you are doing long sessions you will need to bleed air off in the rears after 15-20 mins, but the fronts should be about spot on. They tires also do seem to feel better as the tread wears down, but this could also be me getting used to the car.

As a side note I have been able to join in with some smaller groups renting tracks for open lapping of late. I find it is much more useful for doing this kind of dialing in, as you can come in to the pits every 5-7 laps, make changes and head right back out, allowing you can keep an accurate log of hot workings. In some of the very structured DE's your 20 minute run sessions with 60-80 mins between them will never really allow you to stay at operating temperature long enough to make the right changes, and use them while the car is still hot.

 

What pressure do guys use (cold) for normal street driving?

 

Phil - run factory suggested pressures to protect your tires and rims from pothole damage.

Andrew - new tires will exhibit the pressure build up more than tires which have less tread. Once you wear off a few 32nds they tend to stabilize at the target hot pressure. For Rockit (the gadget guy) I have seen screw in valves which automatically bleed off excess air pressure. I thought they wee really cool until I was told they cost 400 bucks each. For that price, I'll pit more often.

Best,

 

to arrive at 38 and 45 hot, I began at 28 and 34 cold. I do agree that less than 45 hot would be preferred for handling in the rear. I needed to keep the rear pressure up at 45 hot because I was having a significant issue with the rolling over on the sidewall at the uphill and the downhill high load turns at Lime Rock.
Even with these pressures, the lap times were still more than acceptable.

 

Bob R., what do you run cold for the PS2s?

FWIW, I typically run 36/38 cold on the street. Seems pretty good although I recently found that I had 2 bent rears (not sure when it happened). I probably need to adjust my suspension to match instead. JICs 600f/900r (kinda stiff

Running over 40 on the track in the rears do result what you were describing Bob, the tires get somewhat squirrelly.