Sorry to bump an old topic, but some more real world experience for you all.
The ATTESA on my car started going spastic, one rear tyre kept deflating. Now since it's my only car (daily), and the tyre wasn't repairable (sidewall puncture), I had no choice but to purchase two new tyres for the rear. Unfortunately, the only sizes available were 245/45/17 (I called around a bunch of tyre shops). The existing tyres are 245/40/17 (they came with the wheels). So now I have bigger rear tyres, ATTESSA is kicking in every time I hit a bump (Sydney roads are shit so front torque needle swings around a bit). I have to lift off every time, very annoying and concerning for the AWD. I regret changing the tyres. The rolling diameter difference is ~4% yet confuses the hell out of ATTESA.
I'm looking to get a new set of tyres for my 34R wheels ASAP. Hopefully the ATTESSA isn't too bad by then. Good thing I cut down my driving by >50% (catching train to work now). Before when my car had the Factory wheels (225/50/16), no issues. With the R34 wheels 245/45/18 no issues, 255/35/18 no issues.
tl;dr- Run same size tyres on your GT-R!