Another reviewer complained that they are plastic. This is some nonsense! They are durable enough for gaskets, especially with a steel backing plate to take the brunt of each flex. You certainly don't want something that can push out the hole you're pressing the gasket into. I think these plastic rims are ideal as they need to be softer than even aluminum if a puncture or seal is to fail. However, if you have the correct size(s) and are riding straight, this should not be a problem. However, Iβ¦