So looking online if a tire was manufactured 2000 or after you read the last 4 digits, (week,year)
Last i checked there are only 52 weeks in a year.
These wheels came from an 04 d2 I bought second hand.
IF the tires were manufactured pre 2000 you read the last 3 digits (week, last digit of year.)

So the 39 th week of 91? That's seems way too old.

 

DOT date codes are normally inside an oval on one side of the tyre only. There are other DOT codes that refer to manufacturer, size, etc.

 

you were correct...i flipped over the wheel and there it was, 5113
good on you bud!