We do a lot of trailering and my load is quite large.
With 6 tires I have a tendency to be a bit anal about them. What I've done is purchased a IR thermometer from Radio Shack some time back (about $30). I use the Ir Therm to keep a check on the tires and hubs when I trailer. Everytime we stop, I talk the trailer and shoot the temps of my hubs and the sidewall of each tire.
I know what my trailer tires run when properly inflated, I know what temp my hubs run when properly lubbed. I also know what my hubs with brakes run (it's all of them now with the new trailer) when they are functioning properly and not binding.
It's easy for me to spot a tire that is a little low because it's out of the norm and warmer than the others, especially the one on the other side of the axle. The same holds true of my hubs. I see a hub running warmer than it's brothers, it gets checked. The last time, one did I had a outer bearing begining to fail. Several of the rollers were severely pitted and I'm sure within a couple of more trips would have left me stranded.
It's just a technique I've found to be very helpful in preventing me from doing trailer repairs and fix a flats on the roadside.
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Jvalich
http://www.badcock.com'04 FW 288 Vista "Mental Floss"