Let's keep this tire wear debate going... In short, I think it's working exactly as it should. The tires you receive from a pit are the tire you expect to receive, and they perform exactly the same. The ONLY difference appears to be the sound.
perhaps the sound is messing with your ears and causing a less focussed lap that ends up being slower?
Some of the anecdotes about tire quality are related to offline races, so maybe that's a variable?
Here is what I typed in another thread about it:
TIRE WEAR: I have to disagree with those who say that it is not fixed. Cr0w and I both were able to run equal or slightly better laps with the replaced tires, and we were both fairly inconsistent last night, so the fact that we got in the ballpark of similar laps before and after a pit, means they can't be very different, if at all.
The "feel" of the tires seemed exactly the same, but the noise was definitely increased with the replacement tires.
We even put on some Sports Softs to see what those felt like, and while they were not that much different from the RH, once you put the RH's back on, you can tell you're in a racing tire. The replacement tires did not feel like SS's or worse. Since there is no increment of tire quality between SS and RH, it stands to reason the pit stop did not (for us anyway) give us the incorrect tires.