Was missing, tire occ. bouncing, not fun to hear, worse, I thought it was worse than a bouncer in the back. Ebayed a clamp, exact fit, no more noise. Giant Sport Sedan showing even more that it has the royal stuff. Enjoy!

 

Your car was abnormal.
I checked my spare and it is all locked down fine. The locking screw also supports the floor above it, so is necessary.

Even if it wasn't locked down, you'd have to be doing donuts or crossing railway lines at speed to make it bounce