Searching this topic and found this thread. Not too old so I will bump it back up with my findings.
Last year I lost a wheel bearing about 1.5 hours from home south of Kalamazoo Michigan on a Sunday evening. Could not find both bearings in a small town, so had to drop trailer, drive home, pull bearings off boat trailer, drive back up and fix it and then pull it home. Bearing just fell apart, still had grease in it. For a few dollars, I now carry two sets of bearings pre packed and stored in individual baggies and two seals with cotter pins!
I now carry a cen tech infrared thermometer from harbor freight for $20. It may not be accurate, but it is repeatable. My trailer rides almost at 10,000 lbs and has 4 wheel brakes with standard white steel rims. When cooler in the 50's, I get temps 70 to 90 depending on braking. Once warmer, they run 90 to 110. All temps are measured on the rim surface between the lug nuts since I have plastic covers over the hubs.
Last trip at the end, I had one bearing read at 135 while one behind it was 108 and other side was 98 and 102. So that one was pulled apart and repacked. If it acts up again, it will be replaced.
All four tire temps usually run around 130 depending on road temps. I have also come into rest areas and turned off the trailer brakes. That way no brake heat in them and the exit ramp gives me time to coast down and use truck brakes. Let's you also see if one is getting hot due to harder breaking.
Brian
