Why do my boat trailer bearings keep failing?

If your boat trailer bearings keep failing, it usually points to water intrusion, improper maintenance, or overloading. Unlike car wheel bearings, boat trailer bearings are constantly exposed to water — and in many cases, saltwater — making them more vulnerable to rust, heat, and premature wear.

Common Reasons Boat Trailer Bearings Fail

1. Water Intrusion
   • Launching a hot hub into cold water causes a vacuum effect, pulling water inside.
   • Saltwater accelerates corrosion and quickly destroys grease and metal surfaces.
2.  Improper Greasing
   • Not enough grease, or using the wrong type (non-marine grease), leaves bearings unprotected.
   • Over-greasing can also blow out the rear seal, letting water and dirt in.
3. Lack of Maintenance
   • Bearings need regular inspection, cleaning, and repacking.
   • Neglecting service intervals often leads to dry, contaminated, or pitted bearings.
4. Overloading the Trailer
   • Carrying more weight than the Gross Axle Weight Rating (GAWR) puts extra strain on bearings.
   • Even if bearings are new, constant overloads will overheat and damage them.
5. Incorrect Installation
   • Overtightening or under-tightening the spindle nut affects bearing life.
   • Loose bearings cause wobble and wear, while overtightened bearings overheat.

How to Prevent Boat Trailer Bearing Failures

• Use marine-grade grease (Castrol Pyroplex Red, Lucas Oil Marine Grease etc.) designed to resist water washout.
• Rinse hubs thoroughly with fresh water after saltwater launches.
• Stick to a regular service schedule — at least once a year, or more often for heavy saltwater use.
• Always check hub temperature by hand after towing; hot hubs usually signal a problem.