Nowadays more and more new model vehicles do not come with a spare tire of any kind but instead come with a small 12 volt dc air compressor and a canister of one-time use 'tire sealant'. A temporary 'doughnut' spare tire/wheel/jack assembly is a optional add-on at extra cost now. So, if you happen to have a sidewall split or blowout, you're basically S-O-L and calling a tow truck...
