Originally Posted by tenspeed

That sounds like a hub centric rings. They are used when the center raised portion of the hub on the car is smaller than the hole in the wheel. They fill the gap and keep the wheel centered. They remain in place and be sure to remove them when taking the wheels off. Write down the size so if they break, you can get replacements. You can get them in plastic and metal.

I keep forgetting to remove mine on my daily driver when I put the winter wheels on. I find them crushed on the hub in the spring...