scope:

This International Standard specifies methods for measuring tyre-to-road sound emissions from tyres fitted on a motor vehicle or towed trailer under coast-by conditions - i.e. when the vehicle or trailer is in free-rolling non-powered operation, with transmission in the neutral position and the engine as well as all auxiliary systems not necessary for safe driving switched of. Whereas the results of the vehicle method could be higher than for the tyres alone, the trailer method can be expected to give a good indication of the sound emissions produced by the tyres alone.