Tires...how long do they last???

Really? A shelf life? On tires? The last shop I worked for was a tire shop and no one ever said anything...granted the tires we had in stock never stayed in stock for more than a few months, but there were some odd size snow tires that had been in inventory for over five years that stayed in the rotation as new to customers. And Green Diamond (greendiamondtire.com) was always taking tires from us for casings to be used as their remolds. From experience I just replaced a couple of Coopers on Pop's van due to treadwear that were about 7-8 yrs old. That being the case, too, how does Michelin or Bridgestone warranty some tires on treadware 80,000 miles when the average driver sees about 12,000 miles a year? That's close to seven years for full treadwear.... Live and learn I guess.