Air Travel
It will be tight and you will need a seatbelt extender. Pending on the type of plane you are flying on the seat width is 17 to 20 inches for Air Canada and Westjet is 17 inches.
It really sucks...I remember flying and what bothered me the most was the look of horror on the face of the person *****alized that they were going to have to sit beside me. The Westjet flight attendants were kind enough to do some seat shuffling very discreetly so that all were comfortable.