I posted the photo of the bad bearing as bait for comments, but only hooked one. The bearing was only in use for one very long trip. The grease turned completely gray from metallic fines that came from the groove you can see and from the inner race that had a ridge from incomplete grinding. Just another Cheap Chinese Bearing that I am glad I found before a disaster. By the way, four other bearings were showing signs of imminent failure for a total of five of the eight bearings. I replaced all with made in USA Timken bearings. Those that choose to ignore the issue, good luck, I'll try to keep considerable distance from all trailers on the highway.