Tyre Advice needed

I was looking at running narrows and wides aswell, but was told it musn't be done on a quattro car.
I take it your car isn't quattro?

i take it your car is lowered too?
i am running 235/35/19's and on the back it used to "rub" a little.
thanks to some advice from rabbit222 it doesnt anymore.
all i had to do was remove 1 screw on each side under the wheel arch/inner fender if that makes sense.
i removed the screw where the bumper meets the fender and all was sorted.
other that that i doubt you will have issues with run flats.
to eliminate the "rubbing" problem, 225/35/19 would be ideal!