I ran 275's on my stock 17" rims, (tire dealer went up one size by mistake) and they rubbed at max turning.
I got Kumho STX's 265's on my 18's now and love em. Aren't the tires going to stick out past the fenders? My tires come out right in line with the fenders.
Had I known that the handling would be this much improved, I would've changed rims when I first bought my 4R.
Best improvement was wet roads compared to the stock tires. Get the Kumho's, you wont be dissappointed.