Tire sizing questions
 

So sometime this winter I'll be getting a new set of tires for next summer and I want to go a little bit wider at least on the rear tires. Probably either 285 or maybe 295. Is there any kind of rule of thumb that says I should go wider on the front also? or can I keep it at the oem 245? Also, should I keep the sidewall the same? Any other things I should be aware of when going wider than oem?

Going to wide you're going to kill handling. OEM obviously is only 30mm difference. More will be more understeer. Don't look at sidewall, look at overall tire diameter. OEM is only 0.1" difference. I wouldn't go over 0.3". I can't remember what the number is but more than 0.3" and you'll start throwing lights.

So lets say I go 15 mm wider on all 4 tires, there's no problem doing that correct? Edit: I guess rubbing would be a problem.

stick to no more than 40mm difference between front and rear staggered widths. one thing to note, nismo's come with F/R: 245/285

going 15mm wider on all 4 tires is fine as well aside from possible rubbing, but im running 265/285 at the moment

Well you can't go 15mm. They don't make even sizes. You have to go 10 or 20 mm. If you went both evenly you'd be ok as you'd still be 30mm difference from front to rear. You won't rub. What wheels, springs, spacers, camber you plan on running? I know people that run a 295 front and other people run a 320 rear. All depends on your goal. It can be done.