What is PSI?

PSI, or pounds per square inch, is a measurement of pressure. In cars, you'll most likely see PSI talked about in relation to tyres – more specifically, how much air should be in a tyre. Your car's recommended tyre pressures are usually found in the owner's manual or on a panel inside one of the front doors, with figures like 36 PSI being common. You can use a foot pump or an air machine at a petrol station to inflate tyres to the correct PSI. It's important to make sure your tyres are correctly inflated as this maximises the lifespan, efficiency and grip of the tyre.