How to Measure Trailer Hub Drum for Dimensions

Question:

How do I measure the diameter of my drum brakes on my boat trailer?

asked by: Rick P

Expert Reply:

You can refer to the linked photo that shows how to measure both the diameter and depth of a boat trailer hub/drum. When selecting new hubs there are several characteristics you need to match up to ensure compatibility.

Those are weight rating (to match the axle), wheel bolt pattern and the bearing set used in the hub. A new hub has to use the same inner and outer bearings in order for it to fit on your spindles and you want to ensure the bolt pattern for your wheels matches the new hub. The linked article will explain in detail.

I linked our main page for hub/drums. Just click on the bolt pattern you need, axle capacity and bearings from the current hub to see suitable options. A galvanized hub/drum like # 8-247-50UC3 is a good choice for corrosion resistance.