Tire pressure monitoring systems have been required on new cars in the US since 2007. Because of that, you should always know when your tires are getting low or flat without having to look at them or check the pressures yourself, meaning there’s no excuse for driving on a flat tire.
It’s never good to drive on a flat tire for longer than it takes to get to a safe location to change to your spare. If you drive on a flat tire for too long, it started wearing down the sidewall of the tire, and once the sidewall is damaged you absolutely need a new tire. On the inside of this tire you can see how the rubber on the sidewall has been worn away, exposing the cords. There was a large pile of rubber powder inside the tire from the damage.
Mechanical Malarkey stickers available for $5 anywhere in the US!