I had some dry rot on michelin Pro4s but the tires had been off the bike and hanging in the shed for probably 2 years. Still, seemed odd.

I used Pro3 for a while, but they were frail so I switched to the forum favorite GP4000s and those damn tires just wouldn't last. I never wore one out, they always got retired by a cut somewhere. The Pro4 endurance have been great for me and I think I still have a few on hot standby when my current set wears out.