they're the bits that clip them to the wheel - without them you'd have to run by the car holding them on with your fingers

 

:lol:

 

...incidentally, I've just come back from holiday where I saw a total of 4 bugs: 3 unloved wrecks, 2 with Marathon wheels... if only my case had been bigger

 

Thanks Chris. I did wonder what they're for, as I thought the centre cap would fit over the part of the wheel hub that protrudes out, and the wheel when fitted and bolted up would keep it in place?

Where did you go on holiday? Sounds like a place I should avoid going with all that potential!