Audi logo wheel cap

thingiverse

Actual diameter is roughly 29mm, it fits perfectly, doesn't pop out, has a little cut on the side to pop them out when needed with a flat screwdriver. Was designed specifically for the rim in the picture, but it's a common design so maybe it fits more types of rims, maybe only by scaling mine to the needed diameter of yours. EDIT: replaced the STL with another which has pointier clamp heads so it slides in better, unlike the one in my hand in the picture