Tyre pressures play an important part in racing especially in mud where a low pressure will give more grip.
Fitting new tyres - When you receive your new tyres they will probably look deformed due to the way in which they are packed from the manufacturers and it may be quite difficult to get the bead to sit on the wheel. To help overcome this, place an inner tube in the tyre and semi inflate it and leave it for a couple of days. This will force the tyre back to its proper shape and will also force the beads out which makes them easier to fit to the wheels.
Please note that whilst the product images show the tyres fitted to wheels, the wheels are not included in the price!