15x9, +35mm, rear wheels and the 225 wide tires will not fit under the rear fenders, diameter will be an issue at any height.
I had to roll the fenders out as far as they would stretch and then it made a little visual lip on the fenders I do not mind but some may not find that acceptable, my cars are about performance first and foremost so it is a none issue with me. I also had to trim off the factory sealant on the inner to outer fender joint as the tires rubbed it.
It would require something like a +50 in 15x9 to possibly clear without adding camber and then rolling may still be needed, there are no 15x9 in +45 or 50 I know of.
On the front a +40 would hit the coilovers, wheels and tires likely, have to run at least a 5mm spacer, I run 1.5mm spacers with +35mm which I made from some 6061 sheet aluminum I had, they do not need to be machined being so thin.
The 15x8 wheel will support a fairly wide 225 just fine but for better turn in response, feedback, leading to faster lap times the 9" wide wheel is optimal, it helps bring back some of the lost responsiveness of going to smaller wheels, taller sidewalls.
I could of ran 17x9 but they weigh more, cost more, not available when I built the car, harsher ride, etc...not worth it, I would only switch to 16's if going up, 16x8 should of been the factory wheel size!