I went with a 19x8.5" rim and 265-50-19 tire which ends up about .5" taller than stock but fits very nicely in the wheelwells of an "is" model.
I sold the X5 and now this winter set-up needs to go to a new home. Tires are Pirelli Scorpion and they have 2 seasons and maybe 8-9K miles on them. Contact me via PM if interested in taking them off my hands and putting back to good winter use!