[Cliff Beer]

Huw, agree with everyone else here - there's no one universally applicable correct pressure, even for a specific tire dimension. However, there will be a pressure which is correct for your particular car and suspension settings - one setting for the street and likely a different setting for track time.

A key indicator of what's right for your car is tire wear - keep a close eye on the wear pattern on your car's tires. If there is more wear on the outsides of the contact patch than in the middle then you might consider raising the pressure (converse is also true). Of course, if you have greater wear on inside v. outside then you might have camber or toe issues but this can sometimes be moderated slightly with tire pressure adjustments but start with the basic approach above.