If Parc Ferme rules are being used, then you start the race of the tyres that you used to set your fastest lap in Q2 (if you qualified in the top 10). If you didn't qualify in the top 10, then you can change your tyres on the grid. I think you can also change the tyres on the grid if you have Perc Ferme rules switched off.
If have worn those tyres out, by doing lots of laps on them in qualifying 2, then they will not last long in the race.
In Q2 I only do 3 or 4 laps on a set of tyres, then I change them if I want to try again.
So that would be an out lap, one or two hot laps, and an in lap.