This SAE Recommended Practice is intended for hubs and spoke wheels used on Class 6, 7 and 8 truck/truck-tractor non-powered front axles, powered and non-powered rear axles, and trailer axles for which bearing setting is manually adjusted.

The purpose of this document is to establish dimensional guidelines to promote a functional standardization of wheel hubs and spoke wheels in the areas of fasteners, bearing cups, seal bore, and axle drive shaft or hub cap attachment. This document is not intended to exclude the use of wheel hub designs which do not meet the dimensional guidelines for use on defined axle configurations.