[Chris Williams]

This is all just a complete mess, and it varies by state, jurisdiction, and even the attitude of the given cop on the given day. There is absolutely no way to get it right in every case. Some go by registration state, some go by their state. Some go by commercial vs. non-commercial, some go by plates, or by the placards on the trailer and truck. Some go by the license in the hands of the person at the wheel.

As far as I can tell there are only a couple of ways to be relatively safe. Don't have any kind of marking that can vaguely be considered commercial on the rig. Don't speed (by much), and obey all the rules such as signaling and such. Avoid all the weigh stations as if you were supposed to, they just attract attention. And when you do get pulled over, be the nicest guy the trooper ever met. They are always right, you are just trying to get where you are going, whatever you say sir. Smile, offer them a look at your cool race car.

We were pulled over in Iowa on our way from Illinois to Seattle with our new trailer, and this worked for us. The trooper said "well, you're over our commercial limit, but since you're clearly not commercial, I'll let you go." And off we went.