Tyre pressure is not determined by the type of tyre or its size but
upon your vehicle's load and driving application i.e. speed.
To find out what your car's tyre pressure should be, consult the manufacturers tyre placard usually found inside the driver's door sill, glove box, fuel filler cap or under the bonnet.
The placard also displays the manufacturers recommended tyre sizes.
Tyre pressures should be checked when the tyre is 'cold', as pressure increases as the tyre becomes 'hot'.
Take the "cold" reading and check them against the recommended tyre pressures from your placard. Heavy loads or towing puts an extra strain on your tyres. So if your vehicle is fully loaded with passengers and luggage, the general rule is to add 28kpa (4PSI or 4lbs).
Believe it or not, checking your tyre pressure can have a big impact on our environment. An under-inflated tyre creates more rolling resistance and therefore more fuel consumption. By keeping your tyres inflated to their proper levels, you can help maximise your car's fuel economy and minimise its impact on our environment.