I believe it's rim protectors that glue on , mine are gators.

Do they leave any marks where the metal sleeves go in?

Think I'd rather graze the alloys occasionally, and get them sorted out by a man every now and again.

The tyre fitter said that they do leave light grazes on the alloy.

Hope these help. Pics not great.

 

Which tyres have you got on there, Duffer?  My Conti's protect the rims far better than the AGs.  I have them on my winter wheels as the rims are wider and the one and only failing of the Nokian tyres is they don't protect the rims at all.

I changed from conties to marangonis. Decent tyre had them on my mk 5 gti with black gators.