heavyhauler is right. having dealt with it with the race boats I learned one thing. no matter the situation with the DOT, you are wrong and they are right. if you get pulled by the guy having a bad day, prepare for impound and bail money. if you get pulled by one who feels OK about your rig you may slide and go on. it is a roll of the dice and up to the guy pulling you over and as said they have the laws behind them. as of late they have threatened that any vehicle with air brakes (motorhomes, etc) have to have a CDL or face fines. your rig is a revenue source now days so do you feel lucky?