I just put a set on in those sizes. The fronts fit fine without spacers but you might want to use something around 10mm to even out with the rears. I have not done that yet, still thinking about it.
The rears will require spacers of 20mm. I bought mine from Wheel Dynamics. They were reasonably priced and allow you to use the original lug bolts. The fit of the spacers are perfect, excellent machining. The rears fit perfectly, like others have said, 10" is the biggest you would want to go on the 986. I put Michelin Pilot Super Sports on the rims and love the ride, very pleased
Here is a shot of the rear spacer:
