Here's my protocol vis-avis tractor trailers on the open road...
First of all, I do my dead level best to stay off of the super slabs wherever and whenever possible.
If I do have to ride on the open highway, I am always positioning my bike in the most visible lane position possible to the greatest number of vehicles that are in front of me and travelling the same direction as I am. I do this because I am usually travelling at a higher rate of speed than them all and I want them to see me coming before I commence my passing maneuver.
When I approach the big rigs, I make certain that I'm in their field of vision for at least 5-10 seconds, often getting visual acknowledgement from their drivers that they see me and know I'm coming. I scan well out in front of them to verify whether or not there are other vehicles that might be passed simultaneously and that there is sufficient line of sight, clearance and a margin of safety to make my move. Then I drop a gear or two and pass them by in a blink, often being well in front of them by the time they check their mirrors again. Many's the time that drivers give me a thank you dip of their lights or a thumbs up for notifying them of my presence, setting up a safe pass and getting the job done quickly and cleanly. Oh, yeah, I always use my directional signals, too!
Occasionally, such as when there's heavier traffic or certain drivers in front of me are simply brain dead, different tactics and strategies need be employed. Bottom line... I never purposely put myself or others at needless risk.