3" seems like an awful lot, that's a 6" total track width increase.
That is a lot to stretch out from the hub face. Getting a wheel that has been designed with a greater negative offset (smaller backspace) will greatly decrease your chances of damage or premature wear (and give you the look you want) as having a spacer that large can put tremendous stress on the hub. If you want a little more width, you can then add a small spacer to make up the difference.
what year is your av? (you should add your vehicle stats to your signature)
From the factory the 2002-2006 rear track is 1" wider, 66" vs the front at 65"
On the 207-2013, the opposite is true, the difference is 1 1/4", with the front being wider (68 1/4" vs 67" in the rear)
On my 05 I ran 12mm (appx. 1/2") spacers in the front, to even out the track width to 66" front and rear.
On my 08 I am running 1 1/4" on the rears, making my rear track a total of 2 1/2" wider but only 1 1/4" wider than the fronts.
I wouldn't recommend running anything greater than 1 1/2" spacers, especially on the front.