Survivorship bias. If you see 30-year-old rubber on the road, that doesn't suggest that all tires made 30 years ago could last three decades (for example, I remember blowouts and flat tires being *far* more common a few decades back). Now, for sheer longevity absent other conditions or qualifications there may be an argument to be made that the old rubber compounds lasted longer, but modern tires are made with an eye for safety over persistance - better traction, even wear, reduced chance of catastrophic blowout. Personally, given a choice between a safer tire and a longer lasting tire I will take the safer tire every time.