I am concerned to go on long trips without a spare. Especially since nobody has the 21' tires in stock, so one really can get stuck for days on a trip ! I was reading the post which gets on/off topic ( The Tire Rack is proud to be a part of teslamotorsclub.com ! - Page 10) where a suggestion was made that the BMWX5 spare fits. But I can't see anybody posting who really bought it. I found the following link BMW X5 X6 E70 / F15 Spare Tire Kit : Bimmerzone.com . Is that the part ? Anybody tried it ? Would that tire fit in the frunk ?