Piecing a spare kit together - alternate tire sizes
Looking at the diameter calculations, it does look like a 125/80 would be a much closer fit for my non-sport with 225/45 17's. A 145/70 would also be a near perfect fit.
Both the 125/80 and the 145/70 are readily available used (and still mounted on other car's spare rims) on ebay for $80-$100. In both cases, they are on 4'' rims, so it doesn't seem like there should be any problem mounting them on the E60 rim (36-11-6-758-778).
Does anyone see any issues with going that route?
As far as the jack, a well reviewed ones from Amazon are $25-$35, plus a lug wrench for $12. I suppose I could then cut my own foam insert, but I'm intrigued by the Jaguar kits that include the jack, chock and insert tray, also available for cheap (used) on ebay.