Hubcaps - how to keep'em on?

[Hook'em]

For the second time, I had my front passenger hubcap come off while driving. And for the second time I was lucky enough to find it a couple hours after it happened. My Dad had this truck before he died and I noticed that he had etched his phone number along with the word "reward" on the inside (I assume that he had lost them before also). I imagine that I would need a whole new set if I lost one, which I would rather not have happen.

Without having to rely upon dumb luck or the generosity of a stranger, is there a better way to secure hubcaps?