Wheel Spacers 101

DeanoL

G'day guys,
Just looking for some opinions and advice.
We have a 2012 coupe with the sports wheels (Rays 19 inch) front 9 inch width, rear 10 inch, currently fitted with 245/19/40 on front and 275/19/35 tyres on the rear.
I am having the rims stripped and powder coated in gloss bronze (the var is red so it should look great), and I want to space the wheels and it needs new tyres so I also think I will go up a size.
Just wondering how you think it will look going from the above to the new dimensions following.
NOTE: car has not been lowered and we aren't planning to.
Thinking of doing 15mm spacers all round and putting 255/19/40 tyres on the front with 285/19/35 tyres on the rear (both up a size from the originals.
I want it to look flush, but I don't want the tyres hanging out over the guard AT ALL, and I also wonder if this would rub out anywhere??
All advice and opinions welcome and greatly appreciated. Thank you.