I have an 11 maxima premium , I was wondering would 255/55/18 fit on it without scrubbing the struts or wheel wells

 

That isn't the right size at all. Your speedometer wouldn't be accurate.
What is wrong with the factory size of 245/45/18?

 

Nissan really blew it with that wheel gap, didn't they. Along with throwing off your speedometer (albeit only by 3mph or so) it will raise your whole car higher in the air. Which looks worse than the big wheel gap in my opinion. Lowering springs seems to be the only good solution.

 

The point of a camber kit for front tires is so that you don't have uneven wear correct? I have it installed in front but noticing that the insides of my tires have less tread than outside. Can someone help explain?

 

You need an alignment.