Sorry I took so long to reply (roof copllapsed on my house)
But with stock fenders, u can fit 17x10 no problem. All depends on ur offset.

Now with fender flares, u have to cut a portion of ur stock fenders out like S13 Slide said. But once u cut em out, u can either change the offset and keep it at 17x10 or u can go wider.

Remember the other thing about wider rims tho, u pay way more for wider tires (on average 100 - 300 more per tire).

So with that in mind... if someone already has 17x10 with offset of 12, can fit that big of a rim inside the stock wheel well... Skys the limit (please check with ur local rims specialist on how "big" u can go!