This was back in 2009. 17x10 +18 with a 235/40. I believe this was 3* camber when I got it aligned.
Comparing my 17x10 +18 to your 17x9.5 +13 rear, your wheel specs would only retract the wheel by 1mm.
As you can see, the wheel position is already pretty much at the max for factory body. If you run 17x9.5 +13, you may get away with a 245/40 or something along those lines, but not without a roll/pull or excessive camber. Considering the amount of tire you're looking to run, I would think the less camber you run, the better.
My recommendation would be to run a higher offset wheel (let's say 17x9.5 +30~). You should be able to run a meatier tire with only minor massage work on the fenders.