And chocks!I was just about to say that. In fact a tire could not even fit in my trunk. One of my cars does have "run flats" though.
I once was not careful and had a jack go out and a jackstand placed in the wrong spot so it went partially through a floor board. I was not under the car but I learned my lesson fast about making sure I had my jack stand in the right place.
I once had a car drop off a jack while I was loosening lug nuts as it rolled just a hair too much.