Tire sizing...

40 to 332

Interestingly, I'm dealing with the same issue in deciding on a set of aftermarket wheels. I agree with Kenchan in terms of the offset, but coming at it from a non-Nismo perspective. The offset on the front stock 19 x 9.0 Ray wheels is +47. I'm not sure of the exact gap between the wheel and the outside of the front fender, but it appears to be around 20 mm based on what I've seen and read. Others can correct me if I'm wrong. With a 9.5" wide wheel, about 5 mm of the gap will be taken up by the added width of the wheel over stock, leaving about 15 mm to spare before the wheel begins to poke ... meaning that you should be looking at an offset of no less than 30-35(i.e., 47-15) if you want to avoid any significant poke. What surprises me is that lots of owners run Volk TE37 SLs with a +22 offset with oversized tires (255/40/R19) on the front apparently without a lot of poke, even at stock height. Bottom line is that I'm still not certain what the ideal offset for the front wheels should be to avoid poke ... but it appears to be +30 mm or above when you're running 9.5" wheels. Others can weigh-in with opinions and pics based on their experience.