Tire date and decode help please

[Iluv69s]

this is what i believe to be the original spare to my 70 Z-28...Sorry its not a 69   

but I know you guys know the most about these things!!!   thanks CRG

[JohnZ]

Could be original - it was made prior to May, 1971.

[Iluv69s]

thanks john...but there is no way to pin down the date exactly?? are there other numbers??  thanks max

[JohnZ]

thanks john...but there is no way to pin down the date exactly?? are there other numbers??  thanks max

There was no mandated industry-standard format (including the date code) until May, 1971; I don't know of a handy source to decode the manufacturer-proprietary numbering system used prior to that - each manufacturer used his own codes.