255 is safe with the right offset, even lowered; the key thing is the offset of the wheels used, more so than the tread width. If you used even 225s like stock but offset of just +15, I guarantee you will rub, even at stock height. You could drop it 3" with 265s but if the wheels have an offset of +55, there will be not be rubbing. It is the offset that has the greatest effect on the chance of rubbing because negative offset pushes the wheels out.

I have 245s on my Rogue with a 2" drop, but I made sure to pick wheels with the same offset as stock, +40, to ensure longevity of the wheel bearings and to make sure there is no chance of rubbing. With 245s and stock offset, my new tires only stick out 10mm more outward and 10mm more inward than stock at the tread. If I had picked a wheel with an offset of, say, +30, then my new wheel and tire combination would stick outwards 20mm more than stock and the inside face would be just as far in as stock. Now if I used a +15 offset wheel (absurd on a car with stock offset of +40), I would have wheels/tires sticking out 35mm more than stock on the outside and 5mm more out on the inside, and the chances of rubbing would be really high! Plus, the car would look ridiculous, like a dune buggy.

-Ed