I am willing to be wrong on this, and in fact I hope I am so that I can save some money in the future, but I always understood that seven years was the safe age limit for tires no matter how much tread was left or how they were stored or driven. I never let my tires go more than 5 years living in the south because of the extra stress that extreme heat can have on them. Since tires are literally where the rubber (and safety) meet the road, I do not skimp on them or try to save money by keeping them on longer or by buying low cost/low quality tires. I have heard of stretching the expiration date on tires before, but have never known anyone to run tires for 14 years. Maybe I am reading these posts wrong?