I wish these were a bit more precise. There's some slop in the fit to the wheel, which seems to negate the purpose. Not a lot, but like a half millimeter, maybe a millimeter. Enough that it's loose in the wheel, and can slip into a wheel coated with plasti-dip. Problem solved; I shoved my rings into the plasti-dipped wheels and got a snug fit, instead of stripping the plasti-dip and having slop. No reduction in vibration, but at least I feel like I've done what I can do. Meh.