Regarding changing pressure for optimum contact patch...When autocrossing, whether using road or racing tyres, we put chalk at the edge of the tyre down onto the sidewall and then set the tyre pressure low enough that we are going to the edge of the tyre but not onto the sidewall. In my experience, that's how most people set their pressures in autox, and this was also recommended by the designer of the r-compounds I use. A bit different from circuit racing (?) as you're not concerned about rolling resistance, just contact patch and temperature, often on camber limited cars.