Tire Blowout - China-Bomb or Pothole?

Hardly a week goes by without someone posting that they had a "Blowout" and since they had checked the tire air that morning, they "knew" the blowout must have been caused by a defective tire. Many times they jump to the conclusion that because the tire was not made in the USA, that fact seems sufficient in their minds to establish certainty.

I have posted replies that just because they had checked their tire a few hours prior to the failure, that is not sufficient proof that the failure was due to a defective tire. In my experience the vast majority of so-called "Blowouts" are actually "Run-Low-Flex" failures. A tire can loose air for any number of reasons such as puncture or valve leak or even an impact.

I am a strong advocate of TPMS as they can warn of air loss but even the best TPMS cannot provide warning of a catastrophic air loss that can occur after impact damage.

Those that have attended one of my seminars may remember my story of the two impact failures my then fiancee had and how both tire failures occurred some 20 miles after the actual impact. I am sad to report that I suffered an impact on my personal car. I do not remember hitting a specifically large or deep pot-hole with the LF tire but luckily for me I noticed a bulge on the outer shoulder of that tire.

When I saw the bulge I knew at once I had a failed tire and it was only a matter of a few miles before there would be a sudden rupture of the sidewall and the air would rush out the 1" plus hole. Too fast for my TPMS to provide a warning. I recognized the signs of an impact because I have inspected hundreds of tires with similar damage. Some were hard to find as the damage was not even visible after dismounting the tire while others had "blown" while the vehicle was parked so there was no damage from running on a tire with zero psi.

The silver lining to this is that it gives me an opportunity to show the results of my step by step examination. Hopefully this will allow you to have a better understanding of how proper failed tire inspection is done and note that simply jumping to conclusion that since the tire was not made in the USA the country of origin played no part in causing the failure.

Here is the dismounted tire.

 Note the signs of damage are essentially invisible BUT since I did a complete examination before dismounting the tire I can show the physical evidence on the rim that shows the marks left by the tire as it was severely deflected and bent down over the rim even though fully inflated.

  The small lines were left from the sidewall decoration on the tire where it contacted the rim.

Here you can see the break in the interior where the body cord failed under the shock load.

Before I dissected the tire I continued my visual inspection and noted marks on the interior opposite the fracture. You can see where the tire was bent and over extended but did not fail.

A close-up showing the failed body cord. This "crack" measures about 0.6" long

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Here is a video.

Watch the rubber to the left of the break. See how it stretches in a strange manner. The body cord under this rubber is also broken but not visible as the interior rubber has not failed yet. Sometimes all I find are signs of this stretching that indicates hidden failed body cord.

Hope this helps some understand what can happen. If I hadn't happened to see the bulge I definitely would have suffered a rapid air loss with possible vehicle damage or even loss of control and worse.