The best advice you can get on preventing blowouts is to balance your tires, keep them at proper tire pressures, cover them when the trailer is stored, and start considering replacements in either year four or 5. If you buy a used trailer, look at that date stamp on the tire.
A trailer tire is a very different product that an auto or truck tire. Truing a tire if the term means what I think it does (makes sure the tire is perfectly round?), may help the ride quality, but I don't believe it's a blow out preventative.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700