[aerobod]

I think 235/35-19 in the front on ET38 to ET40 19x8 wheels and 245/35-19 in the rear on ET40 to ET50 19x8.5 wheels could work. The diameter difference would be 7mm, bearing in mind the stock 225/40-18 front and 245/35-18 wheels are 8.5mm different in diameter (although the other way).

Alternatively you could use a 19x8 ET40 wheel for both the 235/35-19 and 245/35-19 tyre size, to avoid the severe limitation of finding staggered wheels in the right sizes.