what do you have for a spare tire?

here is a picture of my spare in my Dart. Got it out of a duster in the Junk yard when hunting for parts for my dart

Can you read the date code? Would like to know how old it is.

View attachment Dart Spare.jpg

D78 14, still has the tits and ink on the tread

View attachment sparedatecode.jpg

Not sure what the date code is, can you explain it to me?