We average 4 to 6,000 miles per year pulling our TT. Our Sunline TT came with Mission ST tires LR C. Ran them for 5 years without a problem. Replaced them with Maxxis ST tires LR D and ran them for another 5 years before trading in the trailer for a 2016 Arctic Fox which came with Good Year Marathons. I'll run with them for a few years unless I have a problem with them. Then it's back to Maxxis.
Bearings? Not all Timken brand bearings are manufactured in the U.S. Timken has manufacturing facilities in CHINA as well as other foreign countries and some of those bearings are shipped back for sale in the U.S.