Larger diameter Tyres...
I'm no expert,....
but the car will ride slightly higher
tyre will reach further into the arch (incresing the likelyhood of rubbing on arch, liners, etc, particulary on fronts during steering i would have thought)
slower acceleration and higher top speed (although these maybe minor).

I have always aimed to be as close to std diameter to prevent issues, cos that makes sense to me, and i imagine alot of design went into gearing, suspension etc when that size was chosen originally.