As Joseph notes, it is really a matter of personal tatse .........
The 15mm on the front looks perfectly lined up with the fenders. On the rear, it "can" take more but IMO, it looks the way the car should have been originally designed, ie, not strongly accentuated but very stealthy and thus oem looking ....... the proportions in my view are perfect, it does not scream aftermarket but noticeably looks different ....... and every time I look at the car when I back out of my garage with the other car (I am on a slight slope), I keep saying, that looks nice ........ it is also lowered with Bilsteins ........
The 25 mm on the rear will fill the fender more, and will look more like the 15 mm in the fronts, but again in my view, when you use 25 mm with the oem wheels, and those skinny oem size tires, the wheels/tires appear to be hanging out like low rider cars (I am accentuating in here ...... but you get the point). A 255/40/17 tires will give it a slightly more beefy look ........
Some have opted to go 15 mm front and 25 mm rear. Can't speak of the handling characteristics in this combo, but with the 15 mm all around, the car seems to feel more planted.
Andrie also uses 17/18 wheels and thus wider tires which does make a difference in the looks .......
And both need to be replaced with new longer studs, and that is a story all by itself, there was a post here about a week ago how to replace the studs .......
HTH
