This recommended practice contains dimensions and tolerances for spindles in the interface area. Interfacing components include axle spindle, bearing cones, bearing spacer, seal and wheel hub. This recommended practice is intended for axles commonly used on Class 7 and 8 commercial vehicles. Included are SAE axle configurations FF, FL, I80, L, U, W, R, N and P.

The purpose of this recommended practice is to establish dimensional guidelines to promote a functional standardization of spindle dimensions for wheel end assemblies. Proper hub component dimensions can then be established.