Here in PA its like this. Trucks get truck plates except window vans they are classed as station wagon same as cars, even if its a e350. Now as far as truck weight goes its like this. You can register any weight you want so long as you are not over registered weight either empty or laden. Another catch is axle weight, you cannot be over weight on a axle or axles as stated on the door sticker. Lastly they can get you on tire over loaded weight as well. There are bridge weight regulation (not to be confused with posted weight limits)but that is more involved for this blog. (weight over a given axle or axles spread)
Here is Pa I fought and won in court over a bridge weight violation--Bridge was posted 10 ton limit--Bridge was a short length, say 40ft--I was driving a tractor with 1 drive axle and a 48ft trailer. I won by arguing at no time did I have my entire truck (empty 29,000 gvwr) on the bridge. and showed documented proof of my axle weights). They will also try to get you with the claim if you are registered for 80,000 and assume you are that heavy--but the sign only says weight limit not registered weight limit. If they didn't weigh you, where is the proof?