tyreleader cups performance on track :(

[khooni]

with a set of "new" 2012 Michelin pilot sport cups from tyreleader, i went to silverstone GP yesterday to try them out.

Other than the bonnet catch issue (thanks Shimmy), the cups started ok but degraded consistently throughout the day with even weather conditions and track becoming grippier due to laid rubber. I went from a 2.40 to a 2.49 from 1st session to the final session at 4pm. Dropping at least 1 sec per session of about 5 laps. The car got noticeably edgier, I couldn't turn in as well and once turned in , I couldn't get on the power as much. I also couldn't trail brake very well into the lower speed stuff. It stops ok but I think that was because of my inability to carry enough speed.

This is my second set form tyre leader. The first set was great. I had no issues and they performed flawlessly for 5 trackdays. Even at the end, it felt loads better than the new ones I had, except maybe for the first session. The last time out I got 2.38 so I am bit annoyed that with new tyres I am slipping backwards.

Any suggestions as to why? Have the tyres been heat cycled to death (why and how?). Are they simply too "old" such that the compound hardens right after the first layer wears off? If you ask me now, I'd only be buying proper NEW tyres i.e. made in 2015............... too much of a gamble for me.

[alexk]

What tyre pressures ?
What suspension ?
What geometry settings ?
What tyre temperatures ?

[Rick H]

I bought a similar set from Tyreleader.

I'm not really any good as a judge, but my car was recently driven by a racing driver on Anglesey and he remarked specifically on the huge amount of grip the car had.

You got 5 trackdays from a set of Cups ? ? ? ? ? ? Is that normal ? ? ? ?

[khooni]

tyre pessure is 35psi all round.
suspension is kw clubsport (gen 1) non adjustable
track geometry setup by simpson motorsport

none of the above had changed. I just went on a track day at Snetterton 2 weeks ago and the grip was fantastic.

Yes.. 5 trackdays on a set of cups.

Yes the previous set had a huge amount of grip as well. Maybe this is a 1-off... but.. wtf.

[billyboysm3]

tyre pessure is 35psi all round.
suspension is kw clubsport (gen 1) non adjustable
track geometry setup by simpson motorsport

none of the above had changed. I just went on a track day at Snetterton 2 weeks ago and the grip was fantastic.

Yes.. 5 trackdays on a set of cups.

Yes the previous set had a huge amount of grip as well. Maybe this is a 1-off... but.. wtf.

I run 30 psi hot, how hot was it yesterday.

[billyboysm3]

And how many laps per session,

[khooni]

5 laps.

22deg ambient temperature.

It just wasn't turning in and when I put the power down it just wanted to understeer. My car is setup to understeer so I can brake as late as possible and trail. It's gives me great confidence in that the tail won't snap on me and just gives me the extra turn in required when trailing the brakes. Yesterday it was just a pig, and when i gave up setting times and wanted to hoon, I discovered that because my front end doesn't grip, I have difficulty booting the tail out. The symptoms are that the tyres are fooked.

I'm buying a new set now. ............. but i'd appreciate if anyone thinks it could be something else..

oh, 1 more thing. that bonnet is really irritating me... I'm gonna tape it shut with masking tape.... is it ok to use masking tape on the paintwork?

[billyboysm3]

Grant went to Silverstone a few weeks ago and that had poor grip, Id say tyre pressures to hot and track had poor rubber laid down on it.

[khooni]

9 to 10 secs is a lifetime Billy....... with consistent temps and low numbers of cars on track, I can usually lap to within 3/10s.

Anywho, I'll try again with newer tyres.

[khooni]

one other thing. The tyre pressure light kept coming on despite re-setting and manually checking of pressures using a gauge. What is this for? I never knew what it did nor how it read low tyre pressures.

[alexk]

The pressure is very high in my opinion.
5 laps is nothing.

I tend to do 15-30 laps in a row and I have no such issues even with old cups.
In Monza I do 30 minute sessions.

[khooni]

I didn't realise that but point is it is consistent to all my other track days. That's what I find puzzling

[mattCSLnut]

Tyre pressure too high

Your tyre pressure was too high @ 35 psi (hot or cold) and Cups are very sensitive to both pressures & temperatures. Sounds like you were overheating them from the start.
On track the correct tyre pressure for Michelin Cups is 26 psi (cold) and should hover around low 30's psi hot unless there's something amiss.
The 2012 DOT is perfectly acceptable as the rubber life span of these tyres is around 5-6 years (if they were heat cycled correctly from the start) although they don't phisicaly tend to last that long if you track your car frequently :supz:

[khooni]

Hi Matt,

I accept that the pressures could be a bit high. What it doesn't account for is consistency of the track and why it degrades evenly through out the day.

It should be a 1-time.. oh that's bad and remain the same. But it doesn't, it just constantly goes down. NB I have tried these 35 psi HOT temps for 8 trackdays now and have never felt the tyres going off the way they are doing now. Gradually rubbing off performance the entire day such that at the end, it was basically understeering everywhere.

I'm going to try again and see if i can get new cups on soon and report back.

[alexk]

You are starting with wrong tyre pressures and I believe this is making everything else irrelevant.

One more point.
What do you mean with your car is setup to understeer ?
Again I am puzzled because I have a setup in my car, it doesn't understeer nor oversteer and I go fast with it.

Edit: obviously it can drift when I want it to drift but not on it's own (like KITT)