A lot of the U-Haul trailers used to be rated at no more than 45 miles per hour. Don't know if they still are or not. I would imagine they rate them according to the axle/wheel construction. So doing 50 miles per hour may have been the Montero driver's way of travelling at about the safe speed of the trailer.

So far as the old guy doing 45, well, if he's got a drivers license and the minimum speed is 45, he's not breaking the law. Going 80 in a 70 miles per hour speed zone is. Not meant to be critical - just the facts.