Where do you come up with a weight of 80,000 lbs. for an 18-wheeler? Back in my college days, I worked as a Teamster and loading 40,000 on a trailer was a heavy load. With the weight of the tractor, your pushing maybe 55-60,000. Am I missing something here?
80,000 lbs is standard maximum load and all that is allowed by MN law on the roads. These trucks were filed with rock so no problem making the weight within capacity.
80,000 is the legal limit except for MI where it is 160,000#. 80,000 is 40 tons (last night I got 4 when dividing 80 by 2), so 100 tons is 2.5 trucks at thee legal limit.