By Roger Marble
This is a long post, but I wanted to share the type of questions I sometimes get. This inquiry was about so-called “China bomb” tires.
Good morning, Roger. First, thank you for helping to dispel the misinformation about the “care and feeding” of consumer tires.
My training and work history is in the military and general aviation world. After a 24-year Air Force career and 17 years with Cessna in Wichita, KS, I’ve learned a great deal about tires. I’ve also had a near-miss with some tires back in the day.
I had a set of Light Truck tires on our ’84 Ford E-350 15-passenger van. Not long after a tire story broke in the news, I looked at the tires installed on our van. No defects noticed, inflation correct, continue in service. Four days later, while on the road to KC from Wichita, I felt a vibration develop. I pulled to the shoulder and discovered a blister in the sidewall of a rear tire. I installed the spare and the trip continued without incident.
The following Monday I presented my defective tire to my local tire dealer. He was very apologetic for the defective tire. He replaced the remaining tires with a set of Bridgestones of comparable size. The whole incident was handled well.
At the time I couldn’t get the one tire that failed. I wanted to perform an autopsy of sorts. The dealer wasn’t having any of that, which I understand.
How the problem was explained
At the time, the problem with the tires was explained to me that the sidewall de-lamination was caused by an incomplete cure process. The process was incomplete because a manager thought the vulcanizing process would run its course even after the tire was removed from the press. It was later reported that an inferior compound was used in the process.
So, I guess my question is, in the Light Truck tire incident, was it improper substitution of a material or a management failure in order to increase production that lead to the failures? Do Chinese-made tires exhibit similar problems? Can the NTSB outlaw them? It’s all above my pay scale. Just want to see some reliability in RV tires.
I will continue to recommend your Blog to others in an effort to combat the misinformation surrounding tires.
Reply when you get time. It’s a cold Sunday morning here and I’m working on the second cup of coffee. In this day and age, I don’t do anything in a hurry. My upper arm is getting cold as my sleeve is rolled up waiting on my vaccine, but we’ll survive.
Stay safe, stay warm.
My answer about tire recalls
Where and how did you get the information that the tire with the sidewall problem had some “inferior” compound?
Without a lot more data, it’s hard for me to pass judgment on tires made in the early ’80s. I can, however, relate a personal experience that I have written about previously. This may shed some light on tire quality.
By late 2000, my primary job responsibility had become doing forensic tire inspection and analysis. I came across one almost-new (i.e., weeks old) passenger tire with the steel in the belt having lost all adhesion to any rubber. There was only one tire and at the time no report of other similar tires. Many times single tire issues get set aside, as a “single data point” is hard to establish any trend.
A few weeks later I was presented with two more tires with belt issues. Upon conducting an autopsy, I discovered these tires had steel in one of the two belts, BUT NOT BOTH, having no adhesion to the rubber. The other belt had normal levels of adhesion. Recalling the single earlier tire I dug deeper.
What the problem was
Eventually, after some investigation and some test results from the chemistry lab, it was confirmed that a single batch of approximately 145 pounds of rubber had been improperly labeled in the factory and built into about 150 tires.
I notified the VP of Corporate Quality Assurance. A recall was initiated with the permission of NHTSA (National Highway Traffic Safety Administration). (The NHTSA is like the NTSB but deals with automobiles, not commercial vehicles such as buses or airplanes.) The recall covered some 6,000 tires. The effort required the recovery of all tires that were cured the week when the factory mistake was made.
Technically we knew that with only 145 pounds of rubber involved and the specific process used in that plant, a maximum of 150 tires could have been affected. But since tires are recalled based on the DOT serial and all tires made in any one week carry the identical serial, that was the only option. It turned out that most of the tires were still in the warehouse. That made completing the recall easier, as many times even when recall notices are published a significant portion of the public does not pay attention.
Substandard material cannot be used in tires
Your suggestion that some inferior material was intentionally used in your LT tires just doesn’t seem plausible. This is because NHTSA would have ordered a recall of all suspect tires if there was data that supported the idea that some substandard material had been used.
In modern tire manufacturing, most rubber compounds are used in many different sizes and types of tires. I would say that the sidewall rubber in the Light Truck tire would probably have been used in most if not all LT tires being made at that time. That would have involved millions of tires.
It is also true that tire store dealers do not get detailed training in tire forensics. Therefore, sometimes they tend to simplify the explanation for a problem. When tires are “adjusted” and replaced, however, those tires are sent to be inspected, in detail, by engineers with the necessary training and experience. If manufacturing errors, as found in my example, are confirmed, appropriate action is taken. This is due to the fact that there are serious financial fines for knowingly allowing tires that do not pass DOT requirements to be sold or used.
All tires sold for highway use are certified by the tire manufacturer to be capable of passing the DOT test requirements. The data I have seen, including a number of tires made in China, show that the tires meet the DOT requirements. The so-called “China bomb” concept is a combination of improper use and improper understanding of statistics.
Tires on RV trailers are frequently overloaded
It is a known fact that a majority of tires on RV trailers are overloaded. Also, for a number of years, some 90+ percent of the tires applied to RV trailers were made in China. With these known facts, is it any wonder that there were tire failures on RV trailers and that most of those failed tires had been made in China?
Many people jumped to the incorrect conclusion that since very few tires failed on their passenger cars or pickups and that those tires were not made in China, that the China-made tires must somehow be “defective” even while never being able to identify any specific “defect.”
A side issue. You mentioned a desire to “perform an autopsy of sorts.” This immediately raises the question in my mind of how and what you thought you would do when doing your first tire autopsy? I suggest you read these blog posts where I mention “Autopsy” and ask yourself if you would have noticed or been able to identify the evidence I pointed out in these examples. And if you had noticed the details, do you think you would have reached the same conclusions I did?
I hope this gives you something to read and think about on a cold day in March.