Unfortunately BMW uses run flats on most of their cars except the actual M cars. The M235i is not an "M" car, so it gets fitted with run flat tires. When I had my 135i I wondered the same thing, then when I upgraded to the 1M it came equipped with the right tires. When an M2 is launched, that car will have the stickier, lighter, non run flat tires.
Great looking car!!