Those are for '67 and up. I'm not sure what year they stopped making mag style wheel covers. The '65-'66 mag styles had a raised bowtie "center cap" like this.
You can also see there is a smaller opening between the "spokes". At some point the spokes were painted black. I think that may have started in 1968. There are a 13" and a 15" version as well. 13's for Corvair and I think early Nova/Chevy II. I'm not sure about the dating dial. There are some experts here who can probably tell you when the center section was cast.