Changing tyre size 330Ci

[MartinQ]

I'm getting some winter tyres for my 330Ci. I have 245/40/17 on the rears at the moment, but they seem hard to come by. Would 235/45/17 tyres fit on the rims? I also imagine that the 'slightly' narrower tyres will be a little better in rain and snow.

[E30M3SE]

They'll fit, but you're better off with 225/45 17 all round.

[MartinQ]

I'd rather keep the wheels I have at the moment. I'll look into it though. Thanks.