Yeah fair enough nerkpowers, it is why I said is anyone fanatical enough about originality. I do believe tires age, dry rot, and fail, however I think the six year "recommendation" is self serving tire manufacture's BS. Tire aging is indeed a complex process, much accelerated by UV, so a six, even ten year recommendation is nothing more than a CYA generalization that also helps sell more tires. Our cars likely spend a lot of indoor time, hence less UV and less clock ageing. More concerning may be when tire manufactures begin to design with their own short term arbitrary limit in mind and make it come true! Don't get me wrong, not tying to pump up my tires (pardon the pun), they are indeed old and have used up a lot of clock life no doubt (three are 9 years old, only one is 11), but I assume everyone on this site knows these old tires are no substitute for newer used ones.
Way back before the Ford/Firestone debacle that started the public awareness campaign of tire age, I had a spare tire blow-out in the trunk of my car. It was probably 20 years old and I asked an old tire guy what could have happened. Being in the business he knew tires did this from age and wasn't surprised at all once he saw how old it was. Now it's common knowledge but I take issue with the "safe" number now promoted by the industry.