spare tire
1. A layer of excess fat around one's midsection. I think I need to lay off the junk food, because this spare tire of mine is getting a bit out of hand.
2. An unhelpful, unnecessary, unproductive, or unwanted person in a group. There are a few spare tires on this project who are really holding back our progress. Ever since John's girlfriend started hanging out with us, it's left me feeling like a spare tire.
a spare tyre
If someone has a spare tyre, they have a large circle of fat around their waist. Note: `Tyre' is spelled `tire' in American English. He had long, wavy hair, a big diamond ring and a spare tyre around his middle.
a ˌspare ˈtyre
(British English) (American English a ˌspare ˈtire) a roll of flesh around the waist: He went on a diet to try and lose his spare tyre.