After running a set of 215/45 and 245/40 RE71Rs on my ap2 for the last two years in C street, I'm looking to upgrade to the more competitive A052s for this season but am unsure about sizing. I know the top end street class s2k drivers were running 245/255 for maximum grip with the RE's, but I keep reading that the A052 don't perform as well when they are pinched. I see the top street class NDs are using 225/45 A052s on 7 inch wheels, so is that the best size for our 7 inch front wheels?
Might 245 rears work better than 255s for this tire? The courses in my region are pretty fast, and I usually hit rev limiter in 1 or 2 sectors at every event.

 

For C Street you should stick to OEM sizing. In Street class you should not be upsizing to 225/255 wheels unless you have a CR.

There's also several independent tests and studies out there which suggest a slightly stretched tire performs better than a pinched tire. Especially in cases like the A052 which has a very soft tire wall. The soft walls make the tires roll over easier which can equate to a "vague" feeling steering and accelerated tire wear. That's why A052's don't last long on "Camber Challenged" cars such as in Street Class. In Street Touring class with -3° of camber, it holds the camber angle during cornering and minimizes the tire roll over. Otherwise, stick to 245's.
Better feel, better performance, less money. Win Win Win.

You can read more about this phenomenon here:
Hollis Racing
GrassRootsMotorsports
UrgeDesigns

 

I used to run 245/255 RE71s on stock AP2v2 wheels. While I think more tire is almost always faster, I used to kill the outside shoulder of my 245 fronts much quicker than anything else. I do think a 245 A052 front would burn the outside shoulder very quickly. I think it would also be faster than a 225. Speculation until someone proves it but more tire is almost never slower. More front grip allows you to stiffen up the front swaybar more and transition the car quicker. Up to you but nobody knows until they try.

 

Great info. As Jub said, with RE71s the pinched 245 front tire setup was proven faster in B street for a few years. But now that they are off the market, I'm wondering what the fast tire setup is for our cars in street class. With the ND2s dominating C street, there aren't any winning S2ks whose setup I can copy.
The info i've read on the A052 is that it runs wider and softer. So, I'm questioning if pinching a 245 front tire still has the same advantage it did with the RE71. Like you said, its all speculation. I'm hoping there is somebody on the forum that has tried it and can provide feedback.