I love how you only hear what you want. You are getting paid by the mile, so why would they pay you more to run 65 mph? To run 3 mph faster you would actually save the company money because you would get there quicker and spend more time on the reship dock. 8 hours non-stop? No breaks, no lunch? You must love your job to work that hard. An 8 hour run is about a 420 mile turn. 210 each way with a more accurate average speed start to stop of about 52 mph. So try doing the math again only this time without the calculator supplied by Chicken Little.
And it was the option of installing the larger motor with more weight that would cause more tire wear on the steers.