Never underestimate the importance of your trailer wheel bearings. Its easy to overlook as you cannot see any damage or wear unless you carry out a full inspection. A well-greased, correctly fitted wheel bearing assembly allows your wheels to spin freely and maintains a safe driving experience. Once wheel bearings become aged, worn, dry or have excessive freeplay they can become very hazardous for not only you, the driver, but all others sharing the road.
This quick and easy guide will help you better understand and identify your wheel bearing setup. With this information you can maintain and prevent further headaches down the track.
Identifying your correct bearing setup is important when replacing hubs and bearings on your trailer.

The easiest way to determine which bearings are used on your trailer axle is to take the hub off and look for the reference numbers stamped into the metal of both inner and outer bearings. If the bearing numbers are unclear, the next best solution is to take measurements of both bearings.

Bearings consist of 2 parts

• The Cup which is pressed into the Hub
• The Cone which is the part that contains the rollers of the bearing.

Bearings should always be replaced in a set, the cone and cup together.

The two main measurements required are I.D (Inner Diameter) and O.D (Outer Diameter) of each bearing. It is also very important to know the measurements of your seal as well. This simple component can determine the longevity of your bearings. A faulty, mismeasured or poorly fitted seal will result in premature wear of your bearings.

In a bearing assembly in a hub, the bearing on the inside of the hub flange (the side closest to the centre of the trailer) is called the inner bearing. The bearing on the outside is called the outer bearing.

On common SL type bearings, the inner bearing is always the larger of the two.

The image below demonstrates how to measure your bearings, where to measure and what part of the axle the bearings they are installed.

These are some of the common Trailer Bearing Combinations listed below:

It is good practice to check and carry out basic maintenance of your bearings periodically. Generally, every 6 to 12 months, even if you aren’t using your trailer often. Always check for signs of wear, overheating, lack of grease and freeplay.

Sometimes a visual inspection, regrease and adjust will suffice.

However, If in doubt, Replace!!

Well maintained bearings will last longer and ensure the safety of you and all others on the road.

NOTE: It is extremely important to fit bearing assemblies correctly. Incorrect fitment, or fitment of incorrect components can be very dangerous and must be carried out the right way. If you are unsure, consult a professional.

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