Determine number of wheel studs

Count the wheel studs on the hub. Common counts are 4, 5, 6, 8 or 10.

Determine bolt pattern

For hubs with an even number of studs, measure center-to-center on studs directly across from each other on the diameter. Example: 8 on 6 1/2 means 8 bolt holes with a 6 1/2" center-to-center diameter.

For hubs with an odd number of studs, measure any stud center to the point halfway between studs on the diameter. Example: 5 on 4 1/2 means 5 bolt holes with a 4 1/2" measurement to a point halfway between the opposite studs.

Identify inner and outer bearing part numbers

Bearing part numbers are industry standard and will be stamped into the bearing.

Determine grease or oil bath bearings

Oil bath bearings are not recommended for trailers that sit unused for extended periods of time.

Determine the diameter of the studs

Common stud diameters are 1/2", 9/16" or 5/8".

For drum brake applications, determine brake assembly size

Measure the inside diameter of the drum and the width of the brake shoe.

For heavier axles, determine hub pilot diameter

For 8,000 lb axles, measure the center hole of the wheel.

Determine whether the axle has ABS brakes

All ABS brakes will have an ABS plug on the brake assembly that connects it to the ABS control unit.