That speed limit is widely flouted on rural highways in California and other States don't observe it at all. Typical max speed limit for trucks in the US is 70 or 75 mph, and a few States have 80 mph.
Wyoming's motto should be Drive whatever speed you like!
(It's not an exaggeration because there seem to be about 2 state patrol cars and they're always parked at Walmart getting coffee. If you want to drive 100 as private passenger vehicle, go right ahead. If you want to drive 85 with a rig full of cows, feel free. While Nevada and Montana lost their no speed limit statuses due to federal funding and regulations, but worked around it by issuing smaller penalties.)