Where have you guys purchsaed yours at? I never knew there was such a thing. My new wheels have some vibration and they arent bent so it must need these. I know its not the tires since they were on the stock rims. I found a set of plastic ones for $35.95
Hubcentric Rings for a 2007, Chevrolet Montecarlo with American Racing wheels - JustForWheels.com

Should I buy these?
Thanks
Edit: I guess I should bring home a set of calipers from work and do some real measuring! I saw them on Summit for only $7.99 for a set of 4.

 

My new wheels came with an almost identical set installed from tirerack.com

 

I emailed the ebay guy to see if he knows what size I need for my rims. No response yet.

 

If you have vibration one or more of your wheels is probably out of balance. You could have thrown a weight or they just werent balanced right from the beginning. Before you buy anything I would have the wheels rebalanced.

 

The tire installer I went to mandated I get them or they wouldn't install the tires.. Needless to say im not going to them again after some other things they did. But I had just gone to the counter at pep boys and ordered them. was there in about 2 days. But thats probably not whats causing the vibration.. Like stated above check the balancing.