Not sure of the type of Motorhome in the example above, but my uncle was towing his 27 foot 5th wheel trailer with his new '05 Dodge Cummins diesel when the bearings seized on the wheels on the trailer axle. He didn't realize the wheels had locked up until he literally melted the axle and warped it.
Those diesel rigs have so much torque that you don't notice the drag. By the time he spotted the smoke, the damage was already done.