If you don't track your car, most seem to be going away from the summer only tires out here to grab some extra driving weeks in the colder early spring or late fall weather. When my PSS have outlived their useful life, I will be moving to a tire that gives me a bit more traction when the pavement and ambient temp gets down. Here in AB, even in the dead of summer our early mornings can be downright cold...
Camber and caster set up may have a lot to do with that. Before I learned a little, the inside edges of my C6 fronts wore right to the cords with 6/32 left on the rest of the tire. Expensive lesson. Had the setting adjusted and all was fine. Before my new C7 came out of the dealer, I had them back of the aggressive settings. My PSS rubber wear evenly now.
My inside edges of both fronts on my C6 were at the cords with 6/32 left on the tire. That was at 28,000km for me. We have had members report this at as little as 19,000km...Michelin, as well as a couple others indicate their tires can last up to 10 years but recommend an annual inspection after 5 years. I'm guessing storage conditions, flat spotting your tires for the winter, leaving your car in the driveway in the summer sun, all have varying effects on rubber breakdown and belt adhesion as well. My car turns 5 this year, has 21000km, tires look like new, and I intend to keep driving on them.... But that's just me.
