Why a bad tire gets so hot?
 

Yeah, I know, I've driven longer on my tires than I should but new ones are so expensive and I wanted to get all four at once. I only needed about another week. Left rear tire started going flat. Put air in it two weeks ago and now only an almost bald tire. Got home from work and could smell burning rubber, my tire last night. Left for work at 0-dark-thirty and could hear and feel the problem. Made it to a gas station with free air. I could put air in to some degree but it would not go back to normal. The tire was so hot I could I could barely touch it. Made it home. What makes a bald going bad tire get so hot? Maybe a dumb question but just wondering.

More surface area to generate friction.

Thanks
 

Thanks and I see I posted this in the wrong thread. Sorry.

^ exactly. Not only is more of the tire touching the road, but also the sidewall can rub against itself, and the rim can rub on the tire. This extra friction causes way more heat to build up. Less air in the tire also means that the air will heat up faster.

Jeez dude. You know very well the correct solution is to get a new set of tires. It's expensive, but staying alive is priceless. Your tires are the most important part of your car... it's not an area you neglect because of cost. Don't drive in the rain any time soon.