How to Determine the Right Sizes of Bearings for Boat Trailers

by Bob White
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A boat trailer's bearings provide rotational movement between the hub and the spindle. Boat trailer bearings are particularly susceptible to deterioration because they are frequently submerged in water when launching or loading the boat, but the bearings are often neglected because few owners know how to properly maintain them. Good boat trailers have grease nipples on the end of the hubs for easy lubrication of the bearings.

Visual Determination

Step 1

Clean the old bearing with a rag so that there is no grease on the surface.

Step 2

Look closely at the bearing for its part number. It is typically engraved into a flat section of the metal surface. Two common bearing part numbers are L44649 and L44643.

Take this part number to a parts supplier to get the correct replacement bearings.

Measurement Determination

Step 1

Clean the trailer's spindle with a rag to remove any grease from its surface.

Step 2

Determine the location of the inner bearing on the spindle, the smooth metal surface closest to the middle of the trailer.

Measure the width of the spindle in this location with a digital caliper. Close the caliper arms around the spindle and read the measurement on its display. Two common bearing sizes are bearing L44694 (1.063-inch width) and L44643 (1-inch width).

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