That is new? Probably stacks of tires in a warehouse and they pick from the oldests date of manufacturing to the most recent. Get rid of the older stock. So I guess they're NOS tires. Just because it was made then doesn't mean it's used like you stated. If stored probably a tire made back in the early 1900's could still be brand new today
Mixing gas and haulin' ass
1984 ATC 70 x2
1985 ATC 250R-Ported/Polished, PWK 39mm, V-force 3's, Outerwears air box lid, FMF fatty with DG silencer, DWT wheels, LSR +4 axle, all black plastics
1985 ATC 250R-stock