How do you truckers manage to do this to 6/8 tires and not even notice?

I'm by no means saying this is the entire reason, but going from manual to automatic I have definitely noticed that it is much more difficult to notice resistance when you go to pull forward. How the truck reacts as you let off the clutch tells you a lot about what's going on with it. You also stop paying as close attention to how fast or slow the RPMs are climbing.