Pull the first tire and it will all make sense. Or maybe just think it through with the manual as your guide. I had to flip the discs and the sides to get max extension and the treads going in the right direction. Take a pic of the tread direction before you unmount anything, so you know. There is a middle position, but I could not make sense of it, so I ended up with 2 options - in or out. They start all the way in. Besides, if you are moving them out, the farther out, the more you gain for chain clearances and stability, so why not go all the way?
BTW I have Duos for chains, and they shake the living crap out of me. I am considering moving to ladder chains down the road. They aren't too bad on snow, but when you clear the first pass, they start beating you up bigtime.