I have a low Audi S4.

I was gonna raise it a bit but still have it lowered.
I have 235/40 zr17 tyres on, if i change to 225/40 zr 18 wheels/tyres will i raise the car up by 1 inch???

At the mo it just about scrapes on speed humps , so am hoping 18's will help or am i being stupid?

Thanks
Nick