The "HI" space saver wheel was also used on 1969-1972 Firebirds, so there's no way to know what year you have. If it's the same date format as the KH wheels, the 9 would represent the month and the 12 is the day of the month, so September 12th. But that's just a guess because I don't believe KH made the space saver wheels. As for the year, it's anywhere between 1968 and 1972. However, I see something VERY lightly stamped to the left of the 9. Can you make anything out?
Ed