No, that tyre is not for tarmac only. The first PR4 I've had was Trail version and I did a lot of good gravel roads with no problems at all. Never tried bad gravel roads or real offroad because Trail PR4 hasn't been made for that. But, as I ride only tarmac now, I've decided few years ago to go non-Trail only. 2 years ago I blew my cigarette lighter plug fuse and had no spare, so in the middle of the remote mountain road I had no GPS. Tried to get out but got lost even more. All the time I could see from the top the village I needed to go to and steep gravel road heading down, straight to it. As I was already low on fuel I had no more options as the phone didn't have a net as well.
Well, I just wanted to explore remote mountain...
So, took that road and arrived well to destination. When I parked the bike, rear tyre was completely flat. Long story short, it had two punctures in the mid compound. Tyre shop took care of it but a month later I bought a new one. After that experience, I only plug GPS into my cigarette lighter plug but still use only non-Trail at the rear.