The Spare Tire

Similar to the Third Wheel, the spare tire is that fifth person you bring on a double date who has to sit by themselves.

This can be especially embarrasing if the spare tire has to pull up a chair to a booth for four.

Spare tires are usually your socially awkward homies or people you feel bad for.

a bulge of fat around the waist

In a group of five friends, the fifth friend can be considered a spare tire.
The spare tire is there to replace one of the other friends if they should become absent. The fifth friend is usually the least liked, and is only enjoyed by the others when their numbers start to shrink.

The spare tire is easily replaceable and cannot do anything against the group or risk being replaced. The spare is also subject to harsh criticism by the four.

the flab around the stomach that can stick out over a women's jeans. obtained by overeating, not excercising enough, or drinking too much beer.

HOWEVER... can be kindof cute on the right woman

In hold'em poker, a starting hand of Jack/Four. As in, "What's a Jack for?"

Playing off the expression third wheel, fifth wheel, etc. A spare tire is a person (male or female) that you bring with you on a date. If the date falls through or you're not having fun, you rely on the spare tire to get you through the night.

The huge roll of fat that often times drapes off of a woman's frame because she is so fucking fat and/or drinks to much beer/eats too much pizza, tacos, enchiladas, pasta, or cake. It can be best seen on college girls wearing tight shirts which they intend on showing off their "hot bod," but actually end up showing some nasty flab going about the entire circumfrence of their mid section, or at this point more like mid country they can be so large .....