Tire pressure monitors are very good, and if you have a two (or three) axle trailer, you should have one. The reason is that if a tire goes flat you will only know it when you look in the mirror and see chunks of rubber flying out from under the trailer.
That said, it is good as a preventive measure also, it will alert you if a tire goes low before damage is done to the tire or trailer. Some people remove them from their tires if storing for an extended period.
if you want more technical info 68overlander here on the forums is a dealer, he will be happy to fiull you in.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.