Wheel bearings
The type you have shoots the grease into the back and then comes forward as a basic rule. Most of the time, most folks assume you can go a long way without doing anything but not so. I do suggest a regular maintenace on the trailer which includes greasing the bearings on a timely basis. At 5000 mile intervals, it would be a good idea to pull the bearins to inspect even for peace of mind. As a note, when traveling, stop and put your hand on the axle. If it is warm, you are fine but if hot, something is going on which needs inspection. Ole Crazy Dave gone into hinterland
