When overtaking another car or truck, I always: 1 - look to the other car mirrors: if I can't see his head/face, he provably can't see part of my car 2 - look

When overtaking another car or truck, I always: 1 - look to the other car mirrors: if I can't see his head/face, he provably can't see part of my car 2 - look at its tyres: I find that it's faster to see if he will change lanes by the position/direction of the tyres, specially trucks. Note: yes, where I live, it's common that a truck decides to overtake another truck right in the moment you're doing it too.