笑顔が形状記憶合金のヨコハマタイヤだから
https://blog-001.west.edge.storage-yahoo.jp/res/blog-a5-4e/musyaavesta/folder/1245148/62/70439162/img_0
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSKlx7iudrfGHzIIdAsG5cRpM2ZrYcoWDGKkG2YcW1nVGCfMGWvRQ
https://pbs.twimg.com/media/BBYC22mCUAEP09p.jpg
http://www.koepota.jp/news/2013/11/01/img/0302_10.jpg