Where did I say sub 7 minutes? What makes the ACR-X so good that the Gen V ACR doesn't have a shot at its 7:03 time? By your account the tires. I would also say it may give up some in the chassis too because of the whole cage bit.
What can the (supposed forthcoming) Gen V ACR have the advantage at if its not the tires? More data, better aero, better suspension, more power, probably lighter weight, better gearing, better track conditions maybe a better car overall with more development?
2010 ACR = 7:12.13
2010 ACR-X= 7:03.05
9.08 second difference.
Dick Winkles even said they felt there is still time left on the table and if they had to go back and run a little faster time they could.
IMO the Gen V will be closer to the 7:03 time than the 7:12 time, slicks or no. That being said I would have not be surprised if it eclipsed the ACR-X time and I believe it to be totally possible if they want to. They already know what it takes to run the 7:03, that is a huge advantage.
And you are right, it is all bench racing. I have no idea what Ralph and team SRT has up their sleeves for the future or the rumored ACR. Let's wait and see