Yes there is lots of inconsistencies and they have nothing to do with the reading of any signs. Part of the problem is that some states use a different method of calculation. So your dually truck and trailer could be a 5 axle truck or you could be a dually truck and pay for one more axle. A MH can be a bus or it can be a 3 axle truck. I gave up arguing with them years ago. I even wrote to the Gov. dept. that oversees the tolls and it is impossible to get a good answer. I just pay and shut up! Single wheel trucks pay a car rate and duallies do not.
Moisheh