I want to make this thread live as I want to understand also how much pressure you reduce before you track. My Trofeo R tyres did not make it on time so I will kill the last bits of Pirellis tomorrow for a 20 min short track period. Any suggestion on tyre pressures?
May be a bit late to this but for future reference;
It isn't really a case of suggesting x psi as too many factors come into it I'm afraid. If you are going to take the car on track ideally you'd be best placed getting a spare set of wheels with track focused tyres.
If this isn't an option I'd look at getting a tyre with a stiff wall and high load rating, as high as you can put up with on normal roads. This is going to be a trade off, if you want good track performance your road feel is going to be compromised.
Your average fast road tyre is going to have a wide operating band (temp) ie a reasonably quick warm up time compared to a track focused tyre. It will be pretty good on the B roads and give reasonable grip on track. This means a firm ride on road, whereas on track there will be a risk of overheating. Once a tyre has overheated it's performance will be forever compromised and may be dangerous so managing them will be a priority. Short stints and regular checks will help alleviate this to some extent so limit your laps and invest in a good pressure gauge and if possible a pyrometer probe for temperature.
When reducing pressures for track use its important that the tyre can take it which is why wall stiffness and load rating are important given the weight of the car. Given the tyre has these properties then it's all about ambient and track temperature, and feel.
If you have the above mentioned gauge and probe you will be able to check the temperature of the tyre regularly (roughly, as you can only do it once you have slowed down and stopped), ideally before you go out and as soon as you pit. The main thing you are fighting is the ultimate pressure limit of the tyre, which is why a good gauge is so useful. Check this before you track on the manufacturers site. The pressure increase will depend on temperature, weather and how hard you are pushing them.
One other helpful indicator is the little wear indicator triangle on the side of the tyre (not sure if this is mandatory in the industry or not). You can use this to see how much of the tyre width you are using, ideally you are looking to see wear on the tip. As a rule if wear isn't scrubbing the tip of the triangle you are over inflated, and if you are wearing down halfway or past that you are under inflated.
Whenever you drop the pressure make sure you warm the tyre before pushing it or you may roll the wall of the tyre and risk rimming the wheel or damaging the wall and risk a blow out.
And don't forget to set your ROAD pressures again before driving home.
Not really something you can explain in a sentence but I hope this helps you to decide what's right for you on any given day.
Have fun with it.
R.
