go for it. If to doubt "just 3 inches wide" that is six inches total, and little cars filling out that wide would break thier oem camber, hence skinny little madness crammed into the skinny little wheel wells in the first place. I do not hesitate to insult the fit of alot of cars, I drive a little AWD sube that was tortured by 13 inch wheels for 20 years (I have 14 rims as spares...that was my inevitable obsession). Upon a 15 inch wheel fit and less than .5 inch out of the well, I welded on some new wheel well arches (simply a oem replacement) gained just under half inch each side...and ya know, for less than 1 inch total in width gain, it gave my little sube a fat lookin hiny.
Measure precisely...they are a drag if too big. Much less of a flare can be achieved many times more than not to get what you want, and rather nice looking oem-ish. that site is meant for trucks with muddrs and smashing thier own flares on "things"