2013 S-Drive larger tires?

[IslandTimes]

Clipped a piece of road debris today and bubbled both of my left tires. This is the second time to happen in two months. I'm running stock run flats right now on 18" wheels, but want to switch to larger non run flats to have a smoother ride and a little more cushion if something like this happens again.

I saw a post a while back about the larger tire size without rubbing, but can't seem to find it now. Does anyone know the numbers off the top of their head or have it written down? I believe I'm also running the same size tire front and rear at the moment.