Thomas, the date code for the wheels is next to the valve stem. They will have also have a YA or AO next to the valve stem. I believe the YA was used in 69 and the AO was used on the 70 model year. There might be some overlap of the 69 wheels on the early 70 models. Also if you do a search the colors of the wheels have been discussed many time with lots of info on the colors.
Ray
Wheels
http://www.leverfamilysite.com/Ray_Griffins_Car_Rolling_Chassis.htms
Ray
Wheels
http://www.leverfamilysite.com/Ray_Griffins_Car_Rolling_Chassis.htms