Hmmm, I can't believe those are the right studs. Either that or the holes are all egged out. I recently replaced my rotors, and they were a tough pull to get them apart, and an even tougher one to seat them again. They should be a TIGHT fit. People are saying "oh, it doesn't matter when it's all tightened down", but you don't want the studs spinning, or falling out on the road when you go to change a tire.
The minimum thickness dimension is stamped into the rim — usually hard to read because of the rust. Don't recall it offhand.
You can buy new slotted cross drilled rotors for these, for about $70/pair. Hardly worth monkeying with ancient dubious ones.
