My dad had someone try to steal the wheels off of his much crappier car (not that the Prius is crappy). Now we always buy wheel locks. There's also the occasional teenager that has nothing better to do.
They're all keyed differently.... Cheap insurance. I got a set on sale at AutoZone for $8.00. Nicely chromed, fit perfectly, and same size as OE lug nuts. Cheap insurance... Especially for V owners - there's a lot of II, III, IV owners looking to "trade"... Just don't misplace the keyed socket --- ALWAYS get it back after service/rotate/etc. Or you're SOL. (Keep the little card included with the set in your owners manual as it will have the code for the particular key).
As "DeanFL" stated, it's cheap insurance. Spending a few bucks on wheel locks for added security on a 30K car would be a no brainer for me IMHO. Let the thieves go after the "easy cars" and not mess with yours! The tires themselves could be motivation enough for someone to steal your wheels. The 215/45-17 is a popular size if I'm not mistaken....
I'm ambivalent about them. I park in my garage at home, and a controlled entry garage at work, so most of the time there's little opportunity for theft/vandalism. Mine came on the car at delivery, and I know from experience that my dealer's service department has a master set, so I won't have to worry about having access to mine when the car's in for service. I know someone on another board who sees them as just a deterrent to getting a flat tire swapped with the spare, and not much more.
Take a look at Gorilla locks for 30. Cheap insurance to deter the local teen hood. Won't stop a pro but nothing will.
