I have 205/55r16 on my wifes P5 and it's within 3/8" of the spring mount on the struts. you MIGHT be able to squeeze it in there but I agree about not being the best idea and for more than just "it's not designed that way". Mainly that even if they fit within the suspension, you'll still run the probability of hitting the fender or wheel well when the suspension articulates. That and you'll have even less space in the wheel well to deal with snow caking up.
Having worked in a tire shop I can tell you that the differences in size between brand and quality of tire will matter. (I've seen about 2" tread width difference on some sizes like 235/75r15 used on a lot of light trucks/SUVs (ranger, dakota, s10/blazer). Same size tire but the cheap brand is tiny compared to the name brand. Mounted on the same rim the good tire looks like (__) while the cheap tire looks like \_/. It's crazy what people will put on their car to save $20
I think the consensus is probably won't fit, not a great idea if it does, upto you to try it if you really want