I would agree that the tires are almost always the weak point. After that is definitely wheel bearings and then spindles. In PA, anything over 3k# GVW has to have brakes, a breakaway, and be inspected annually and not every shop has the authority. Federally speaking, if you buy a trailer that is OVER 10k#'s (no matter how you want to register it) It requires combination registration (In PA about $500 versus $200 a year) and a CDL. Most state police officers (Not just DOT officers) (And Ohio, especially**Ask me how I know) are well versed in trailer and weight rating laws. It's only a matter of time before local cops become well versed in it too. The main reason towing any trailer in Western PA is tight lace is because 4 or 5 Easters ago, a tree chipper came loose from a commercial dump truck and killed two little girls and a mother. It turned out that the guy was on unprescribed pain pills but was a result of not closing the pinnel, securing the chains, or hooking up the break-away. Now if you have a marker light out, you are definitely getting shook down.....