Ugh I just ran into a tire problem and was wondering if anybody could help me...

So I'm supposed to drive to E3 tomorrow to catch the last day. But I got a screw in one of my tires which ended up destroying it. (The stock Bridgestone Potenza on my '05 STi).

I have 3/16in left of tread (about 12k miles on them) and I measured a new one and it has about 5/16in of tread (on their website, they say 9/32in). So I figure, at the minimum, the circumference difference is 3/4in. which is more than Subaru's 1/4in. limitation which would void my warranty on the differentials....

So unless somebody has some used Potenza RE070s (225/45 R17 90W) that I could pickup today or tomorrow, I guess I need to buy new tires.... or should I not worry about Subaru's 1/4in rule and just buy a pair for the rear from the dealership? If I have to buy new tires, any recommendations?