My wife'* spare tire recently got a rock through the tread and went flat. We got a replacement from a junkyard through the dealership, but... they left the flat in in the trunk, too. What'* the proper way to dispose of it?

pay to have a tire dealer dispose of it...usually a buck or two

Take it to a tire store. Usually they'll take it for free as a courtesy...around here they will anyway.

go to a tire store and throw it in the pile with all the other tires they have.

Make a tire swing