By Roger Marble
NHTSA (DOT) – Improper Repairs:
“A plug by itself is not an acceptable repair” to fix a flat tire.
“The proper repair of a punctured tire requires a plug for the hole and a patch for the area inside the tire that surrounds the puncture hole.”
“Punctures through the tread can be repaired if they are not too large. But punctures to the sidewall should not be repaired.”
“Tires must be removed from the rim to be properly inspected before being plugged and patched.”
NOTE: Michelin, Goodyear and Bridgestone say the same thing.
The use of sealant or Slime or “Fix-A-Flat” or something similar is in some cases worse than using a plug to fix a flat tire. Not only can’t the inside of the tire be inspected, but the use of such product may void any tire warranty and make it difficult or impossible to make a proper repair.
Here are some pictures from one of my seminars on RV tires. In the first picture you can see all the crack damage in the tire. These can lead to unexpected tire failure.
I hope that you can see how the use of an external plug only, or just a sealant, without an inspection of the inside of a tire, could give you a false sense of security when you need to fix a flat tire.