Originally Posted by VVG
Remember that bigger tires also equals more weight, more noise, more rolling resistance. Unless you are supercharging, the stock set-up is just fine. It would have been very easy for BMW to put different sized tires on the stock car but they didn't. There is a reason for this.
If you are supercharging, 275/30 & 295/30 is a great combo, other wise the stock tire size and maybe up to 255/35 & 275/35 is optimal.... No extra weight, no extra noise, a touch more sidewall for added comfort and no fitment issues whatsoever under any circumstances.
Just because you can fit bigger tires, doesn't mean you should. Tires that get too big for their intended purpose also start to look a little ricey.
BMW wants to keep as little stock of tires as possible, which is why the Forged 19s and the ZCP rims have the same size tires. If I had ZCP, I would go with 265/285 on PSSs because it does not rub and keeps the stock stagger while increasing the contact patches by a good amount