Tires: auto tires, cold climate, tire industry

Question
My mother has a 2003 Chevy with approx 12,000 miles.  The tires are original with no previous punctures.  Should she be considering replacement of the tires due to the tires' age?

Answer
Henry,

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.