To answer your question:Yes, we do charge more for a trailer wash than a tractor wash, which is stupid, but that is what the industry has seemed to set. The trailer has nice, easy-to-wash flat surfaces and it isn't as necessary to get a trailer as clean. A tractor is much more difficult to wash, gets a lot dirtier than a trailer, and the driver is much more likely to complain if it isn't relatively clean. A person can spend twice as much time on a tractor than a trailer to get it clean, all for less money. Obviously, pricing varies dependant on numerous circumstances, but we typically charge anywhere from $2.00-$5.00 more for a trailer, hoping that the extra money we get from them makes up for less profit on the tractor. Are you strating to test the "fleet waters" a little? What kind of experiences have you had so far?