I've had a vehicle right behind me flip and disintigrate into pieces in my mirrors. I've had a vehicle spin out of control on the opposite side of the highway, cross the median, and pass less than 50 yards in front of me head-on. And I've spun a car in a heavy downpour, crossed two lanes in one direction, miss the median concrete divider, spin back the other way acrcoss three lanes facing the wrong direction, and come to a stop in the grass between the highway and access road without hitting anything. But one of the scariest was a truck that lost it's spare tire from under the bed. The wheel bounced and rolled, staying upright from gyroscopic force, with the long metal bar that normally threads into the underside of the pickup still attached perpendicularly, like the long spinning spikes on the end of a Roman chariot wheel. It bounced roughly head high two or three times and passed within 10ft of my left shoulder. It felt more like 2 inches from my shoulder at the time.