This document specifies the characteristics of wheels for all heavy rail track gauges. This document applies to heavy rail vehicles and applies, in principle, to other vehicles such as urban rail vehicles. Five steel grades, ER6, ER7, ER8, ERS8 and ER9, are defined in this document. NOTE 1 Steel grade ERS8 has been introduced in this document as an optimization of steel grades ER8 and ER9 due to contact fatigue (RCF), taking into account service feedback from Europe, for example, BS 5892-3 in force in the United Kingdom. Some features are provided as a Category 1 or Category 2 function. The requirements defined in this document apply to cylindrical bores. Most requirements also apply to wheels with tapered bores. Specific requirements for tapered bores (e.g. geometrical dimensions, etc.) are defined in the technical specification. This document applies to monobloc wheels in vacuum degassed steel, forged and rolled, with surface treated rims, which have already been the subject of extensive commercial applications on a European network or have complied with a technical approval procedure according to EN 13979-1:2020 to validate their design. Annex A describes the evaluation process for accepting new materials that are not included in this document. This document defines the requirements to be met for wheels; the technical approval procedure is not part of the scope of this document. NOTE 2 A "surface-treated rim" is achieved by heat treatment which aims to harden the rim and create compressive residual stress.