Why does it matter? When they wear out we replace them. If they didn't last long enough we search for something less sticky and more harder. (much restraint shown now....)
Buy a tire you like and use it till it wears out. Some peeps get 6k miles and some get 16k miles on the same tire.
Well, it matters to me because I've got a 4000 mile trip coming up in June. I bought the bike March 2nd, and I've put 1500 miles on it. Doing the math, it appears that if I keep this up I may not have enough tire left by then to make the trip.
So, I either:
- ride the wheels off the thing and replace the tires before the trip, or
- I park it and ride the ZRX 'til then.
I think I like option one better
But your point is well taken. YMMV