i am sorry i am not able to understand the above figure.
city origionally comes with 175 width tyre which is way too thin. i went for 195 and i was more than happy.
about ride stiffness, i am not sure as city already has got a very stiff suspension. Its stock tyres were very hard, after changing them i would obviously feel them relatively softer.
about the width part, i dont think its steel rims cannot support the width, i beleive they can easily.