spare tire HELP. 17" donut for m3?

[HBpredhunter]

id like to ditch my spare wheel (to sell to make a couple bucks, and to ditch some wieght)

but id like to get a compact spare or something lighter than the contour i have, but that will fit my car... can anyone recommend a rim?

[egebhardt]

I want to do the exact same thing. I need a donut that is large enough to fit over the rear disc brake. The extra weight is ridiculous. Maybe a can of pressurized goop is sufficient too. Any ideas?