3 dight numbers are 90's 4 digit numbers are 2000's. That is according to the ABC video that was posted recently on Moparts. 408 per ABC Video is 40th week of 1998. The video further showed that Tires over 6 years old are very dangerous and can be fatal as the tread peels off and the tire becomes uncontrolable. I have recently had 3 trailer tires on different trailers do this very thing. The tires remained aired up but the tread peeled off. these were 2000 and 2001 tires.