I'm really not the best person to be replying to this thread but I would have thought that they would be ok in the dry. They would only need to get warm.
I don't know anything about differing compounds as you wear the tyre down but if you've only just reached the wear indicators then I believe the only thing you are starting to lose is their ability to disperse standing water.
Someone who knows what they are talking about will be along in a minute
