I saw it seperate from the car, and slowly roll off the side of the road, down an embankment. The impossibility of this event is what makes it remarkable. I don't remember the car swerving or imbalanced... just watching the smooth decision of one wheel of the car at a particular curve to continue on a trajectory it apparently preferred, rather than the new one the care had chosen, the surprise of seeing it move on its own, first rolling mostly with us, and then away and independent. I was not more than five, and I was probably younger. The disorganized and dreamlike quality to the memory -- one of only a handful I have from that time period -- says that my brain and experience were very different than they are now. If pressed, I will admit that I don't know that it wasn't a dream, while still slightly favoring the perception that it was real.
I don't know where we where, either. One of maybe 500 Utah mountain or canyon roads, probably. Just my father and I, riding along in the car, and me staring out the window at a world so wide and unfamiliar that a five year old couldn't even take that fact in -- only barely perceive the fresh strangeness of every shifting scene. The wheel separating was strange, too, but in the usual way, so I had no perception of this. My father was calm. We stopped, I think, he traversing the embankment and retrieving the wheel, me staring, and perhaps asking cheerful and childish questions. Did he put the wheel back on? I think so. I don't know. He must have. We drove away, I think to a welcome home and the chance to mention this new experience.
Where the sound of the wheel coming off should be in the memory, there is a child's parody of sound effects. I hear a clanking and rattling of metal, but there is something to the quality of that remembered sound that has a signature of my own on it. I trust it a little less than the rest of the memory. Or I think: maybe it was a hubcap that came off the car, and in my mind at the time, this was the same thing. It would explain the stability of the car.