Here are some more photos comparing the width of these two tires (same size tires on the same size wheels):
Federal 595 RS-R 255/40R17
Enkei RPF1 17x9"
Dunlop Direzza Star Spec Z1 255/40R17
Mach V Awesome 17x9"
I took these photos because some people are claiming that the 595 RSR's are super wide (even compared to the Star Specs). They are very similar in overall width (at least in this size), but the Federals have a much more rounded sidewall and the Star Spec's are very square. I think this may actually result in the Star Specs having more tread on the ground for the same overall width. Both are fairly wide tires for their given size.