I got my rims and suspension on I'm using 175/50. The shop said if I used 195 It would rub the insides. By the way the Cusco suspension I ended up buying feel real sweet around the turns
you would only need spacers if your buying/fitting alloys with the incorrect offset, which is +38 or +45, get the right offset alloys and you'll be fine,
I have 42mm ish drop on the back with a panhard rod installed and it rubs with a load in the back, after fitting the HD rear swaybar it no longer rubs - strange!