Always check tyre air pressure when tyres are cold after vehicle has stopped. Use accurate tyre pressure gauge. If check is made when tyres are hot then inflation pressure above 4 psi than the recommended cold operation air pressure by the vehicle manufacturer is permissible. Check the pressures of your tyres, including spare, once in a fortnight and before any long journey or if traveling with a heavy load. Ensure a dirt-free valve cap is always fitted.