Jotaro vs Dio: How can Jotaro both move and stop time in road roller fight? I don't get how Jotaro can launch his "oraoraora" against the road roller (7 seconds since time was stopped) and also stop time at the 9th second of Dio's "The World" ability (i.e. just before getting behind Dio).

From what I understand, Jotaro is able to move for 2 seconds in Dio's stopped time because Star Platinum is also able to stop it and they end in the same "stopped time dimension" together. So, I think Jotaro shouldn't be able to stop time after facing Dio's as he has already used his 2 seconds to stop the road roller between 7 and 9 seconds.

If instead "counterattack" and "stop time" are different ability, shouldn't Dio be able to fight back Jotaro?
It's correct that Jotaro can move in frozen time. And by that logic, DIO can also move in frozen time for 2 seconds.

Jotaro can stop time for 5 seconds and he uses it (refer to time stop) in the 9th second of DIO's time stop, and at this moment, Za Warudo's time stop has been replaced by Star Platinum's and DIO can only move for 2 seconds. He ended up being frozen in the 11th second after Za Warudo was activated, but since it has already been replaced by Star Platinum's (refer to time stop), DIO has used up the 2-second that he can move in frozen time.

I don't really know how road roller work.