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Saturday, September 15, 2012

What is involved in doing a tire inspection?

 Some of you may wonder how I can provide an opinion on what caused a tire to come apart when all I see is a picture or two. 
For many decades my primary job was to perform tire inspections and "autopsies." I estimate I did more than 20,000 inspections, so I was able to build a good experience base for my observations.

My findings were many times presented to a customer that did not want to accept responsibility for the failure, so I needed to be very thorough and to provide an easy to follow explanation.
 Here is an example of just one such inspection.
The tire was reported to have "blown out on a local road” The lack of facts and data did not help in the analysis of the tire.
However I was able to establish that the tire suffered a sidewall puncture, lost air and after running significantly under inflated at highway speeds for a number of miles the cumulative damage to the tire resulted in a flex fatigue failure.

Photo -1 above
                Shows the 2 piece condition, which is indicative of, flex fatigue failure.

Photo -2
Shows the result of melted body cord – Body Cord melts at 350°F to 400°F

Photo Tire-3
Shows the abrasion on the interior from running a few miles at essentially zero inflation

 Photo 4 shows a larger portion of the interior. Here I noticed the location of a possible small sidewall puncture.


Picture 5 is a close-up of the area of interest

 Picture 6 is what the outside looks like.

The question is ... How do I prove there was a puncture?  If I used a sharp probe like an awl some would think I might fave made the "puncture" myself. Over the years I learned a trick. If you take a paper clip and straighten it out, you can use it like a probe. The un-bent clip isn't strong enough to hold and doesn't allow you to force the end of the clip through the sidewall of a tire but if there already is a hole, the paper clip can be guided through the already made puncture.

Pictures 7 shows the clip on the inside

Picture 8 shows the clip on the outside at the suspect location.


                The tire was not defective but failed due to being operated significantly under inflated. The under inflation was caused by the small sidewall puncture.

Corrective Action:
                Use a TPMS. Instruct driver to be more attuned to ride & handling degradation, as this tire should be operated with 80 psi under normal conditions. A slow leak would have taken some time and resulted in significant changes in handling and vehicle response.

Some punctures are hard to find. Sometimes the puncture occurred in the heavily damaged portion of the tire so it is impossible to demonstrate the puncture. Melted polyester body cord is physical proof that a tire was run with only 10% to 20% of the proper inflation.


  1. "as this tire should be operated with 80 psi under normal conditions." Should both tires of a dualie be held at 80 psi?

  2. Larry Each position of a vehicle has a specified minimum inflation. For motorized units this is normally based on the expected loading and this includes duals. For trailers (which have no duals) the normal cold inflation is the inflation shown on the tire sidewall.
    If your actual load indicates you need 80 psi to carry the load of the heaviest end of the axle then all tires on that axle should have 80 psi.

    Send me an email (seen under my picture on the right) if you need further clarification.


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