This video from a gas station in Maryland is a perfect example of why you need to make sure your tires are in good shape before filling them up. And why you always should use a pressure gauge.
It shows a man refilling the front right tire of his Ford Focus sedan until it unexpectedly explodes, taking the entire right fender (as well as some sound-deadening material) off of the car and launching it into the air. The man is visibly shaken, clutching his ears from the undoubtedly brutal shockwave caused by the explosion.
I talked to Shawn Elliot, uploader of the video and one of the employees present at the gas station when the incident occurred. He told me the man in the video was trying to refill his tire with air and correct a groove in the sidewall caused by driving with low pressure. That groove couldn't be fixed, no matter how full the tire was, and it depressurized in spectacular fashion. If you've ever seen a video like this before, you'll understand how lucky the man is to walk away without a grievous injury.
The fender was later found in a tree branch approximately 25 feet above the gas station. As you can see from the picture above, it's not in very good shape.
Elliot said he uploaded this video as a PSA for tire safety. If the person in this video had replaced the grooved tire with a new one instead of trying to refill it, this incident probably would've never happened. Let this be a warning to people driving around on damaged tires: Get them replaced, or something seriously bad can happen.