Jounce Stop Bumper ?

I've seen more than one truck drop to the stops and bulge the tires. There was a recent thread on here about adding air bags. Did them on a friends truck that had a cap with tool boxes. It was near bottomed before he put a LOT of tools and parts in. Till we added the air lift bags, the only time it came OFF the stops was when he hit a big bump.
I watched another guy getting topsoil from a job site once. One 'scoop' from a large loader and I thought the tires were gonna pop.
As for most cars, not likely to hit. Now that we are discussing it, I'll have to look at how far the leaf would need to flex for that to happen. I know an engine in the trunk can bring them down pretty good...