The importance of checking wheel bearings
To underscore what Rick Macdonald wrote, most insurance companies in the US now do not cover damage as a result of bearing failure on boat trailers because of too many past claims. Before we left for the West Coast with our Magic-Tilt trailer with 15 inch wheels using a 5-bolt GM rim, my 10-year daughter and I unpacked the bearings, inspected them for flaws with a magnifying glass (found none), and replaced the old seals when repacking. It is a messy but not difficult task. We carried one complete set of new bearings and seals in case needed (they weren't). While driving, my wife and I stopped often and I checked by hand touch the hub temperature, tire temperature, wheel brake drum temperature and bearing buddy status each time. The outside air temperature was between 88 and 110 degrees during trailering. Obviously, these are extreme conditions. The o-ring on the starboard bearing buddy failed with a very minor leakage of lubricant in South Dakota (in the middle of nowhere) as evidenced by an increase in hub temperature and, of course, grease leaking into the nipple area of the bearing buddy. The o-ring seal was replaced and the missing lubricant replaced. This solved the problem. With this one exception, the hub temperature was never warmer than the air temperature. However, trailer tire temperatures were always hot after trailering at highway speeds. The stops are important to let the tires cool down. We noted no temperature increases for the tires at or below 30 mph, (or 50 km/h, eh).At the start of each towing day, trailer tires were checked for cold inflation to 50 lbs/in (topping up was only needed twice in 7 days) and bearing lubricant amount was checked by viewing the inspection port on the bearing buddies. Each day bearing grease was added to top off. After 7 days of towing, 2 small tubes of lube had been used.To reply to Mark Price, maintaining the trailer and especially the wheel bearings in proper condition is essential. Confidence in being able to repack bearings on the road is part of that confidence. I agree that comfort in towing a boat is also essential. My wife Michelle did her first towing of a boat trailer on this trip and actually did about 1/3 of the distance. - Kevin.