Have you got the covers with the hole in the middle or the ones that look like a fake nut kinda thing?
 
You'll need the tweezer type things. They should be in the spare wheel with the jack etc
 
The tweezers thing is made of black plastic and quite small. It should be in the foam toolkit holder in the spare wheel but it's easy to miss it. I have the ring pull type tool as well and spent a while wondering how the hell it was supposed to work before I spotted the tweezers.