Are those the rears? How long do you expect them to last?! I'd think of 20,000 miles as a reasonable lifespan. I'd always been under the impression that "only" didn't start until 10,000 miles ;)
When you're not buying racing tires, it's not uncommon to find tires that last 50 or 70k miles. Those are the lifespans I expect in my tires. If I were using tires on a track, of course, those numbers would change since I would be buying track tires.
