tyreleader cups performance on track :(

[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]

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

[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)

[mattCSLnut]

Originally Posted by 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.

Unfortunately there is no "could be" about it You've run these Cups now (over inflated) for 8 track days, overheating & over working them (due to the wrong pressures) so you've probably altered their compound in the process. Now they are at the very end of their life it's natural for them to behave the way you've described. They are telling you it's " GAME OVER "
Don't forget to "Heat cycle" your next new set of CUPs before any track action

[estoril]

Originally Posted by mattCSLnut

Don't forget to "Heat cycle" your next new set of CUPs before any track action

Just for the record, how is this best done?

[s.mac]

Agree with all, pressures too high. Also suspension set up, this can be different on the same track on different days. Needs tweaking to suit on the day.

If you are that keen you should check the tyre temp across all tyres and 30 to 32 psi max HOT, I would be closer to the 30

Lap time could drop because you are over driving chasing times. You might not think it but been there done it. Lacking confidence on grip could also hinder times.

[Rick H]

8 tracks days - same set of Cups? Is this realistic? I was expecting 2 maybe squeeze 3 at most?? what's normal for somewhere like Oulton?

[billyboysm3]

Originally Posted by estoril

Just for the record, how is this best done?

Me, shimmy and Duncan paid track group to do ours or alternatively go for a very long drive heating up the tyre gradually. Spa would be good or drive to track night before.

This saves them from going hard, I managed to wear mine down to canvas with little loss of grip.

I'd say 7-8 track days if all dry, plus a couple of wet ones.