The draft for ISO standard ISO 11819-2:2000 for CPX tyre/road noise measurements includes specifications for a set of four standard reference test tyres. These commercially available tyres were selected to cover the different mechanisms responsible for the generation of tyre/road noise. Three were chosen to be representative of passenger car tyres and one to be representative of heavy vehicle tyres. Since the draft standard was first written, these tyres have either been superseded or discontinued. It has therefore been necessary for ISO/TC 43/SC 1/WG 33 (Measuring Methods for Comparing Traffic Noise on Different Road Surfaces), the Working Group responsible for the Standard, to define recommendations for an updated set of reference tyres, at the same time considering whether fewer tyres could be used. This paper provides a summary of the recommendations for the new reference tyres and an overview of the review process which formed the basis of the recommendations, presenting specific results from the evaluation of candidate replacements for ISO tyre A.