I am running 15 inch wheels on my Datsun 510 because not only do they look better, but, 14 and 13 inch tires are hard to find, especially in low profile sizes. And even 15 inch tires are getting scarce. My old Chevelle had 15 steel wheels that where a bit wider than stock and finding decent tires to fit was not easy, or cheap.
I know some of you are thinking donk size wheels when you hear larger wheels, but that is not always the case. Nothing wrong with going one size up on wheels.