This proposal has been prepared by the EPPR IWG Secretary, in close collaboration with WLTP IWG experts, in order to align the definitions of chassis dynamometer rollers between EPPR and WLTP GTRs. The content of this overview has been followed by WLTP although the specific definitions are not contained in GTR No. 15. This proposal recommends elaborating and introducing such definitions into the EPPR GTRs.