Metrication is mostly complete. Road signs solely use metric measurements, as do the speedometers and odometers in motor vehicles produced after 1974, but there was no requirement for pre-1974 vehicles to have their speedometers and odometers converted to metric, so vintage cars display miles and miles per hour, and privately imported vehicles, such as classic cars, do not need to be so converted. The sale of oil and petrol is sold in litres, but tyre pressure is commonly referred to in pounds per square inch.