Oh they definitely do for semis no matter what state. We can be pulled over at anytime and get a roadside inspection. There's 3 levels. Level 3: Not a huge deal. Just checking your logs and making sure you have your paperwork in order. Level 2: Basically, anything they can immediately see plus they check to make sure all lights, horns, and windshield wiper/wiper fluid works. Level 1: You're about to get fucked. That's what those warehouses behind the scale are for. They're climbing under and on top of every inch of your truck and trailer. So if you see a truck pulled over, it's not necessarily because he did anything wrong. Especially if it's DOT that has him pulled over. They have an unwritten quota for truck inspections just like anything else. Edit: I reckon I should clarify that this is for any commercial vehicle; Not just tractor trailers.