In general truck rules apply to commercial vehicles registered and plated as trucks. Since our coaches are not so designated the laws don't directly transfer.
The other side of this becomes one of common sense, which has been proven to not be all that common.
A good example would be this. I am approaching a steep descent which shows a truck speed limit of 20 mph and a truck pull off at the top of the hill (or mountain if you like) with maybe runaway truck ramps along the descent, common sense would suggest, rather strongly that my coach and toad weighing about 36,000 lbs might want to do like the truckers.
Not to say I would stop at the truck pull off at the top, but I would want to be sure my brakes were functioning and I was geared down adequately so that I could control my rate of descent without overheating my brakes. You will only need one experience of being out of control going down hill with your heart in your throat and your backside puckered up like a duck's watertight orfice and assuming you don't crash you won't repeat the same thing a second time.
