We recently replaced the staggered factory 15" alloys with wider 15"x6" all around and are now running 195/50/15 summer performance tires.
This was initially done to evaluate the forthcoming WORKS suspension mods, and I have to say, the car has been transformed. A lot of the initial understeer is now gone and I can even feel a little squirm at the tail end of the car with a lift of the throttle - something that the old set-up would never allow, but that can help tons with adjusting the cornering attitude of the car via throttle input. The car is vastly more capable of carrying speed through corners, and braking feel is also improved. There is zero rubbing with this set up. There does not appear to be any penalty in ride quality, and as an added bonus, there is a whole universe of great tires available in the 195/50/15 size (which, now that they are all the same size, can also be rotated on the car for longer life).
Needless to say, we couldn't be happier with this mod.
** DavidV