I read alot about guys changing tire and wheel sizes on their cars. However, don't the cars come with their suspensions tuned for the tire size they come with? I know about the +1, +2 thing (10mm greater tread width, 10 profiles points lower, one inch greater wheel diameter) to preserve rolling radius. But can't even this screw up ride and handling, let alone if you don't follow the formula? Does the suspenstion have to be retuned to match a new tire size, and it this doable with just alignment adjustments?
I have two reasons for asking this. I'm thinking about a 328Ci. Like the sport package (both seats and wheels) but not wild about the OEM tires (Bridgestone Turenza). Maybe it's worth getting a non sport package and doing my own upgrade with the tires I want (Bridgestone S02PP). But the non sport is set up for 205/60-16 all around, not the 225/45-17 and 240/40-17 that come with the sport package. Will going wider/lower profile screw up the suspension tuning on the non-sport car.
Also, I'd probably need winter tires (I've slid backwards down too many hills). The Blizzak M01/M02 look good, but I understand that narrower/taller tires are better in snow. Because of this, I'd probably go with a -2 setup, especially if I went for the sport package. Now I know the snows will have less performance vs the summer tires, but will changes sizes screw things up even more? Also, I can't find a Blizzak listed in a -2 size for the 328 sport package. What would I use?