In areas of height limited lanes, you should follow the directions regarding height restrictions no matter what. That’s common sense. In most states, 2 lane highways treat the left lane as the passing lane and the right lane as the travel lane (though people seem to mostly just travel in the left lane anyway). On a three lane highway, the left lane is for passing, the middle lane is for cruising, and the right lane is for vehicles that are exiting, entering, or otherwise need to go below the speed limit. The right lane should not be used for cruising when there are three or more lanes. Check with triple A if you don’t believe me