What width are the front and rear tires?
I don't think you can go much more than 12.5" in the rear without either rubbing the suspension or sticking out too far.
You have about .5" to add on the inside and about .5" on the outside. The 345/30/19 will cause the car to sit closer to .75" lower in the rear and I would think the 265/35/18 would cause the car to sit .5" lower in the front. Usually, I wouldn't recommend lowering the car this way as it throws off the speedo, etc..
Instead, you may want to consider going with the 345/35/19 Pirelli Corsa (which will be almost the same ride height as the stock tire- .2" lower) and an appropriate tire for the front.
Good luck....