Tire date codes will most often be shown on only one side of the tire. If you don't find it immediately, look on the other side of the tire.

Before 1990 there were no date codes.
1990-1999, the date code was three digits.
2000 on, the date code was four digits.

Old Date Code 1990-1999 above. --- Newer Date Code 2000 and later below.