I posted a thread on the VXR forum, but I though you guys may find this information useful as well..
I'm running Goodyear Eagle F1 Aysemmetric 235/40/18 tyres on the Vectra VXR and will be fitting a Tyre Pressure Monitoring System shortly, which includes tyre (internal air) temperatures.
Now I appreciate its the actual tyre tread temperature which is more important, but as a guide I wanted to find out what the internal air temperatures should be for optimum grip and performance when taking the car on the track?
I need to set the upper warning alerts on this new system and didnt know where to start.
I read an article from Toyo 888 who suggested the optimum tread temperatures were between 85C and 95C, and ideally a maximum difference across the tread pattern of 9C.
But that didnt tell me what I should guess for the internal air temperature (which is what my gauge measures)
I then wrote to Goodyear UK and got this reply...
Thankyou for your email.
I am making an assumption that your system measures the air temperature inside the tyre, which is linked directly to tyre pressure. This shouldn't be confused with surface tyre operating temperatures which are normally measured with a pyrometer. In all of our track work, it is the surface temperature that we measure, not the air temperature, and then adjust tyre pressures to ensure we have the desired footprint on the road to even out the temperatures across the tread face of the tyre.
Therefore, the focus should be on maintaining tyre pressures. Our recommendation for track days is that the pressures when hot should be no more than 5% more than the standard pressure for the car (or equivalent to the 'high speed' tyre pressure recommendation for your car, if this is listed in the handbook). Often, this means you may have to lower your cold tyre temperatures to keep the hot pressure in this range, but this depends on track temperature, the circuit and the duration of your stint.
I'm sorry that there is no simple answer, but experimenting with cold tyre pressures to get the right hot pressure reading will ensure you get the optimum performance.