Never saw this happen before
Driving home the other day there was this on coming chev pu. Then I see this tire rolling down the road towards me along side this pu. I think WTF and stop. Tire launches itself off the road 100' or so in front of me. PU drives by in his lane in a nice straight line less the left front wheel...the entire assembly. The rotor, hub, spindle, caliper, it had none of it left. Looked like it was dragging on a circular shaped cast iron part on the road as it went by, sparks flying. Truck pulls off on the shoulder a couple hundred feet behind me. I assume this truck must have had a one piece bearing/spindle assembly like my dodge 4x4 and corvette has, and it must became unbolted somehow. I don't know how that could happen all of a sudden.
I was amazed that this sudden loss of such large and important components at hwy speed didn't result in a total loss of control of the vehicle. I wonder how often this happens. That integrated bearing/hub/spindle idea raised a red flag in my head the first time I saw it years ago.