Tires: replace or not to replace spare?, cold climate, ford pickup

Question
We own an F-250 Ford pickup extended cab. We got it from my wifes parents.  The spare is one of the original tires that came with the truck.  This is a 97 year model.  The tread on this tire is very good and the date of the manufacturer is October of 96.  What we want to know is, is this tire still safe to put on the back of my truck?  Is there an age limit on a tire that you should replace it regardless of the tread?  Thanks for answering my question.   George

Answer
George,

Recent bulletins from the tire industry indicate that tires degrade simply due to time.  The age of a tire is important even if the tire is unused.  There some disagreement over how to best express this age limitation, but my take is:

If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years.  If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years.  States in between are  ..... ah ........ in between.

The tire in question is approaching 15 years old - so, yes, it would be a good idea to replace it.