Reduced rolling resistance saves fuel and cuts CO2 emissions. Class A tires deliver the best fuel efficiency, with each subsequent class through to G increasing fuel consumption by between 0.42 and 0.56 mpg for a car which does 36 mpg.
Secure grip in wet conditions is crucial for safe driving. Performance is graded into classes, A to G (although D and G are not currently used). The stopping distance between a class A tire and a class F tire can be as much as 18 metres.
This is the external noise made by the tire and is measured in decibels. The more filled bars shown on the label, the louder the tires.