I sometimes think that big rig drivers don't know what is going on way back there. As a slight aside I remember an incident quite a few years ago when I was driving my 99 Miata on hiway 2 just north of Calgary. I had just got off an eight hour flight from the UK to Calgary. As I was overtaking the semi trailer I noticed that the last wheel on the truck had a hub that was cherry red and was smoking.
I got abeam the truck driver and pointed back towards to the wheel. He had no idea that anything was amiss until I signaled to him.