I tried 20mm in the rear and I was rubbing on my 215/45 tires. I am also pretty low, def tucking tires, almost tuckin wheel. I got my rear fenders rolled and still couldn't get away with the 20mm spacers.
So my advice for
Tae would be 20mm in the rear max unless you wanna poke out. And if you wanna tuck tire you will need so smaller tires (like 205/40) and maybe some camber adjusters. If you don't wanna roll fenders then stick with 15mm. If your not lowered or planning on going really low, then up to 25 mm will probably fit.
Just be aware of the dangers involved in using spacers. There's a ton go horror stories and I have yet to find one friend who would recommend them. Although I have some on myself please BE CAREFUL.