[Mr70]

When looking at the valve stem area,starting left to right you'll notice the initials MI with a 9 under it.That stands for Motor Wheel Inc.-the manufacturer.
The number 9 is the last digit of the year the rim was assembled.In this case 1969.
0 if it was 1970.
Next is the month of the year,in one example from above,9 for September.
Move over to the right of the valve stem to see the number 24,which stands for the day of the month,the 24th.
Next is the application code,AO,which in this case is the Magnum 500 wheel used on some Super Sport equipped Chevrolet vehicles and Yenko Deuces during that time period.
These wheels also were coded YA during the 1969-early 70 model useage.