I've got Toyo Eclipse
http://www.toyotires.ca/tire/pattern/eclipse 205/70/15s on. They are the absolute largest diameter (26.5") tires that will fit. In fact, when new there is about enough room between the tire and front spring holders to get a thick piece of paper between, and they just slightly scuff the wheel well if I turn fully left or right.
The correct inflation for a tire is directly related to the load upon it. Since the 205s are designed to handle double the load I have on them I must reduce the air pressure to keep the centers from wearing thin before the edges.
I've gotten used to the light being on all the time. It doesn't bother me, but would be nice to have the warning indicator for when I really need it. 26 psi front and 22 rear (unloaded) seems perfect for getting even tread wear. I'm due for a new set this fall but if they go on sale I might jump on them sooner.
For anyone wondering why, I'm getting more overdrive (approx 8%) with the larger diameter tires. It's not much but it's better than nothing. Wish I could get 3.0 final drive gears, and do a mod to the 6 speed tranny to lower the first and second gear ratios. Nissan did NOT engineer enough overdrive into the 6 sp version. The CVT delivers 27% more overdrive than the manual 6 sp.