Will 0.9" taller tires fit on a stock E91 xDrive?

[JamesAustin]

I don't need new snow tires this season (the Blizzaks still have plenty of tread left) but I'm the kind of guy who will check what's available anyway.

MaLColM (my 2011 E91 xDrive) has 225/45R17 tires, which is the official spec and what every online tire configurator suggests. Except for Nokian, which not only recommends 225/50R17 but claims that is the factory default.

So I looked around and found TireSize.com where there's not only a tire size calculator but a tire size comparison calculator. According to that, a 225/50RT17 tire's diameter is 25.9" verses 25" even for a 225/45R17. Will that +3.6% keep them from fitting under my stock wheelwells on my stock suspension?

Oh, and I know both front and rear diameters MUST be the same...

[JamesAustin]

And the Nokian, at +3.6%, may help to correct your stock BMW speedometer error.

The page also has a speedometer error calculator. Unfortunately, BMW just adds 3 MPH to all speeds (lazy AND annoying!), so the Nokians will only get me to perfect accuracy at roughly 81 MPH. Then again, maybe I can make that work.

Police officer: "Do you know how fast you were going?"
Me: "Yes! Exactly! I was going 81 MPH!"
Police officer: "Yeah, in a school zone. With the school speed limit sign flashing."
Me: "You see, officer, my speedometer is only precisely accurate at that speed."
Police officer: "Oh. Well, okay then. Carry on."