Rear Wheel Studs – movement

Last night, I removed the rear wheels from my Trailblazer and noticed that there was movement in all 8 studs. They are only held in place by push nuts…is it common for these to have some play in them? This does not seem like the best way to secure wheel studs……are there any known alternatives to using the OEM push nuts? Are they designed to stiffen up when the lugs nuts are tightened down?