Michelin Cups Pressure Guide

[Pip1968]

I thought I would post this guide from Michelin. Maybe it could be a sticky if it is deemed useful enough. The other Michelin guide sticky no longer links into the web page so may need to be amended or deleted.

Pip

A Guide To...Track Day Tyres and Pressures

You very quickly realise the importance of tyres when you start participating in track days, as they play a vitally important part in getting you round the circuit quickly and consistently. If you make a poor tyre choice, or use your tyres incorrectly, this can drastically reduce your performance and even affect your safety on the track.
Always check the condition of your tyres before you attend a track day for wear and damage. Remember, you will be loading the tyres more heavily than usual and you will need to have road legal tyres to drive home on at the end of the day. Wheel nut torque should also be checked.
Tyre Pressures
Car manufacturers’ tyre pressure recommendations are normally based on “cold” tyres, but on a track day you also need to monitor your pressures once your tyres are up to temperature in the “hot” condition. This is because track use generates much higher tyre temperatures than road use. This extra heat leads to an increase in tyre pressure, meaning that bleeding some air out of the tyres during the track day may avoid excessive over-inflation.
When you get to the track, regular track day goers may know what tyre pressure they normally start the day at. If this is not known, start the day with the car’s standard tyre pressures, with a view to monitoring the pressures when the tyres are “hot”.
Generally, for Michelin road tyres, the optimum “hot” track pressures will be higher than the standard recommended pressures, typically by around 6 psi (0.4 bar). Heavier cars tend to need a greater increase over the standard pressures than lighter cars. If your tyre pressures are too low, this can lead to excessive flexing of the sidewall, a sensation of sponginess, a lack of steering response and abnormal wear. Pressures that are too high can lead to reduced grip, light steering, and even localised overheating.
The Pilot Sport Cup, Michelin’s road legal track day tyre which uses motorsport compounds, is designed to run at a hot pressure of around 33 psi (2.3 bar).
Tyres run cooler in wet conditions, so if it is wet, you can start at your car maker’s recommended pressures, and little adjustment will be required while these conditions last.
If you are not using Michelin tyres, you should seek the advice of your tyre manufacturer.
At the end of the day, and once your tyres have cooled down, you must re-set (usually re-inflate) your tyres to the car maker’s recommended pressures before driving on the road.
It is worth investing in a robust, accurate pressure gauge to ensure consistency with your settings, and a tyre inflation pump may be useful if no air line is available at the track.
If you are a regular track day goer using slick or semi-slick tyres, you can consider measuring your tyre tread temperatures to assist in suspension and tyre pressure set up. Motorsport teams use this technique to optimise vehicle performance, but it may be a step too far the average track day enthusiast.
For further advice on tyre choice and tyre pressures contact the Michelin technical helpline on 0845 366 1535 begin_of_the_skype_highlighting 0845 366 1535 FREE end_of_the_skype_highlighting .

Tyre Checklist:

• Check your tyres before you set out – correct size/type, no damage, tread depths, pressures.
• Will you have sufficient tread depth for the journey home?
• Monitor your tyres’ hot pressures, and keep an eye on tyre condition throughout the day.
• Remember to use the normal road pressures on the road once the track session is over.
• Always fit valve caps. This is the primary seal and prevents dirt entering the valve.