Yes. I have definitely heard about this. Its not just the drying out part, its the overall breaking down of what makes a tire a solid reliable piece of rubber.

I believe 10 years is the absolute max safe length to wait.

maybe the theory of 5 years is never BUY a set of tires that are older than 5 years.


http://www.safetyresearch.net/safety-issues/tires/