No substitute for a spare tire kit (tire/wheel, jack and lugwrench) as anything can happen to a tire or wheel. You hit a rock and dent the rim or tear the sidewall, what are you going to do? Sure, you can get towed to the nearest tire shop or dealer but what if it's on a Saturday night and all is closed until Monday, how will you get home? Also, say it's mid day during the week, Smart dealer is a mile away, you get towed, how much time does that steal from your vacation spending hours waiting for them to locate a tire and fix it? Also, this is a rare tire size, I believe only for the Smart, on top of that it's a rare wheel with 3 bolt holes, you are in the middle of nowhere, how long with it take a typical tire shop 200 miles away from the nearest Smart dealer to get you that tire or wheel?