As Steve pointed out, there is a lip that bead must be seated on. You can see in this pic that I am using pry bars to get the bead on.
Again, as you're tightening your rings down, you may see it deform in a conical shape a bit as in, the edge making contact with the tire sits higher and the edge inside the wheel dips downward. This is TOTALLY NORMAL however, IF you get to this point and you're already getting up to 20 ft. lbs. of torque and still have a BIG gap, you need to install the spacers.
Also, the bolts thread directly into the aluminum and that's why tightening to the proper torque is so necessary.
The Coopers are thicker than Nitto's. Also, ATX uses steel inserts but so far I could see, there weren't any on the Trail Ready wheels.
I believe so.