Unfortunately, I am going to be the nay-sayer here, but please do feel free to ignore me.
As a former Tire Rack expert once said: "Spacers are evil".
The fact is that spacers (a) add some minor rotating weight right where you don't want to have it hurt your performance, (b) separate the wheel from the hub outwards enough that the suspension axis contact line with the ground
may no longer lie within the tire contact patch if the spacer is large enough and (c)
perhaps affect the heat transfer from the brakes to the hub and wheel, reducing the quality of braking.
Also, if your spacers are not hub-centric - too large an opening for example if they were not designed for Nissan/Infiniti hubs - they could put some sideways pressure on the lug nuts. Leading to wheel imbalance in a heartbeat, or lug failure.
Whether you feel it or not under normal (not hard driving conditions), you are changing the geometry of motion of the wheel and tire, and this will have some effect - perhaps minor in some cases - both in terms of handling and tire wear (inside vs. outside).
My bottom line has always been: don't add spacers
just for looks - if you
really want to "fit" the well better, get wider wheels and tires, with the correct offset, that work without affecting the suspension geometry.
Z