For my the products I design, I have used and would use again NMB, NSK and SKF bearings. These are all ball bearing assemblies. For the vast majority of applications (including bicycles), even so called "cheap" Chinese bearings are more than adequate if they are properly lubricated. For non-competitive riding, an automotive wheel bearing grease will keep your trailer wheel bearings happy for thousands of miles. I suggest solvent (70% isopropyl alcohol is fine) cleaning the balls, raceways, cones, etc, drying then immediately apply the grease to all the metal surfaces inside the bearing system. Use nitrile gloves - your finger oils are bad for bearings.

For the vast majority of applications (including bicycles), even so called "cheap" Chinese bearings are more than adequate if they are properly lubricated. For non-competitive riding, an automotive wheel bearing grease will keep your trailer wheel bearings happy for thousands of miles. I suggest solvent (70% isopropyl alcohol is fine) cleaning the balls, raceways, cones, etc, drying then immediately apply the grease to all the metal surfaces inside the bearing system. Use nitrile gloves - your finger oils are bad for skf bearings.

Trailer wheel bearings need to be inspected (Flat spots on bearing rollers, broken cages, or rust and pitting) once a year for wear or damage and a lack of lubrication. It is recommended if the bearings are worn to replace the bearings races at the same time the bearings are replaced. Trailers that subjected to extended periods of non-use or submerged in water should have bearings inspected and packed with grease more frequently.

Trailer wheel bearings should last for years and provide you with thousands of miles of travel---but they won't last forever. In some cases they even fail completely if they haven't been maintained correctly. Part of a maintenance schedule should include replacement of wheel bearings before they fail. The procedure isn't that difficult if you have about an hour and a few small tools. Front and back wheels are similar in procedure to change bearings and only require slightly different tooling.

An important aspect of bicycle maintenance is to grease the Trailer wheel bearings. This helps to avoid costly future repairs and give you a much smoother, more comfortable ride. The nachi bearings are between the cup in the wheel hub and a cone screwed to the wheel axle.