This Safety Spair commercial promises to repair your punctured flat tire without changing it. "Safety Spair that automatically fixes flats." Consumer Reports tested Safety Spair, along with other tire-sealant compressor kits, as well as aerosol cans that promise a quick fix. To test, this car was outfitted with 15-inch, all-season tires. Gene Petersen punctured one of the tires with a small nail and put the products to work. All the aerosol cans were able to seal the small hole and inflate the tire, which kept going for more than 100 miles. But Consumer Reports found all the cans had difficulty with larger holes. And since an aerosol can is under pressure, you can't keep it in your car in hot weather. "It can explode. So that kind of limits its use. You're not going to keep it in your car. You're probably going to keep it at home, and when you need to use it, it's not going to be with you." The compressor units are more expensive but can be safely stored in your car. You plug the compressor into your car's power adapter and attach the sealant canister to your tire. All the compressor kits fixed even larger holes. They also come with a gauge to make sure you're inflating to the recommended pressure. Consumer Reports found the 80-dollar ContiComfortKit works the fastest, with enough sealant to repair a wide variety of tire sizes. ."