This International Standard specifies the dimensional requirements for attaching wheels to hubs on tractors and machinery for agriculture and forestry. The flat attachment type with centring on a central bore is the recommended type for future equipment. NOTE 1 Characteristics of attachments with spherical or conical centring on the stud hole are shown in annex A. Specifications indicated do not imply that the wheel is interchangeable from one vehicle to another. NOTE 2 Wheels fitted to driven front and rear axles which incorporate gear reduction or corresponding mechanisms within the wheel hub envelope are not covered by this International Standard.