Originally Posted by Heathpack

Yes, I know and that is actually what I intend to do. But the question was "when?"

But nevermind because I have since asked the same question of one of my trusted cycling advisors. The wear indicator is going to be a pretty conservative predictor of when the tires should be swapped out. You can certainly go well past the point of the wear indicator being gone if the tire seems to be in pretty good shape. You should replace the tire sometime after the wear indicator is gone but before the tire fails, where exactly in that range is something of a judgment call.