Had to get one tire replaced, where to put it?
 

The background:
Upgraded all 4 tires to PSS at 8,000 miles on the car. Ran two autocrosses with the tires, and had them rotated at 13,000 miles. The two tires that used to be in front are now in the rear and are slightly worn from the tough cornering, but evenly worn.

However, 1,000 miles later (at 14,000), the driver side rear tire got a nail stuck in the sidewall :(
Took it back to Discount Tire and they replaced it (I purchased the warranty when I got the tires). However, with one new tire in the back, and one tire with the sideblocks having some auto-x wear and tear... I can notice the car tending to pull under acceleration.

So my question is, where should I position the new tire? Should I put the front tires back in the rear, providing steady feel under acceleration, but now the car is possibly a bit uneven when breaking and entering corners? Also in consideration, there's an auto-x this weekend that I am now considering skipping... and I have a 1,000 mile round trip road trip home coming up soon.

Opinions appreciated...

Update: thinking of going back tomorrow and biting the bullet, buying the 2nd tire. It's 153 + mount and balance + 23 for the new warranty certificate. It's not the best time for me to spend $200, but I will probably do it.

Either way, would love to get some opinions.

My perspective is the track, so take this for what it's worth: For performance, you put your best two tires on the front so the car will go where you want it to. At least you do with DOT-R tires and with slicks - for new street tires with 10/32 tread depth on an AX course, I'd still try them in front first. After running them once or twice in the front, I'd then rotate them to the rear to see which mounting I could drive faster. HTH