I would LOVE to have an 18 wheeler for hauling wood.
Unfortunately, they cost too much all around to be practical. I pay $22.50/year to keep my truck on the road. It costs so much just to get an 18 wheeler on the road it is not worth it. I can carry a cord of wood at a time, so I don't fret about how many trips it takes. If I have a trailer along, I can carry 3 or 4 cord and then it is really efficient. If I figure even a measly 15 mpg hauling 4 cord of wood, that comes out to about 25,000 lbs. So.....1 mpg/1,667 lbs! HAHAHA that sounds bad......
HAHA...comes out to $0.15/mile!!!
In reality I would probably average about 18-20 with that kind of load.