Busting the Myth of 5 year tire life.
I sold tire pressure monitoring systems for 9 years and regularly presented lectures on tires. One of the most frequently heard statements was, "You should get new tires every 5 years." NOT SO! I ha...
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Retired tire engineer here! I used to analyze failed tires like DSDP Don said. And, Yes! You will not find any experts at the tire shop level.
I was also involved when the Ford/Firestone thing hit some 17 1/2 years ago. Allow me to fill everyone in on tire age.
The tool really needed to analyze tire aging is a shearography unit, which can "look" inside a tire and see if there is a separation. These are expensive, so tire shops will not have one, but every tire manufacturer does for just this purpose.
First, there are 2 problems: The first is that most tires wear out long before the tire ages out. That limits the amount of data available to analyze.
The second is that heat is a major driving force behind tire aging. Tires operating in Phoenix age a lot faster than tires operating in Minneapolis. So unless you are careful to account for ambient temperature, any data collected is going to have a lot of scatter.
In fact, the RMA (Rubber Manufacturers Association, now the US Tire Manufacturers Association), did an extensive study shortly after the Ford/Firestone thing to see what could be determined by looking at tires being scrapped. I forget how many places they looked at tires, but it was at least 5 different cities. They examined thousands of tires and cataloged everything they could find.
They could not pick up any discernable pattern - except to say that old tires tend to fail more often than new tires. The scatter on the data was HUGE!! - making it impossible to say anything precise about tire age. The discussion at the time was how there must be other factors involved and how could those factors be determined to sort the data out further.
That's why you will find tire manufacturers state a 10 year limit. Everyone who looked at the data could see that. But it was clear from the data that tires from AZ looked a lot worse, but how do you say something about that in a clear and unambiguous way?
And part of what added to the confusion was that certain brands used a rubber compound in their sidewall that resisted cracking - and that rubber compound had nothing to do with the critical area between the belts! That meant that the normal indicator of problems was not available in every brand.
Further, I looked at our company's data and it was clear that the desert southwest (AZ, NV, TX, CA) produced the vast majority of the failures - and it took a few years for those to appear.
Since I retired, I have been studying failure patterns of tires as reported on the internet, and it seems like tires on trailers have far more issues than tires on motorhomes. It's hard to sort out, but it looks like a combination of loading (Trailer tires are more heavily loaded than other types of tires) and the tire design (the internal construction). This somewhat correlates to the country of manufacture, but it also correlates to the lack of attention given to the design (internal construction) of ST tires versus LT tires - BUT - this is thoroughly confounded by the manufacturer (brand).
Put another way, LT tires were given a thorough look-see after the Ford/Firestone thing and all the major tire manufacturers changed construction, but I'm pretty sure ST tires weren't.
Now this adds fire to the ST vs LT tire debate as well has the Chinese vs US debate, but both of those debates ignores the fact that those things could change - AND - since we are looking at reported failures as our data, it is easy to overlook if the reports disappear - and that appears to be what is happening.
And that could mean a reset on the age debate.
I was also involved when the Ford/Firestone thing hit some 17 1/2 years ago. Allow me to fill everyone in on tire age.
The tool really needed to analyze tire aging is a shearography unit, which can "look" inside a tire and see if there is a separation. These are expensive, so tire shops will not have one, but every tire manufacturer does for just this purpose.
First, there are 2 problems: The first is that most tires wear out long before the tire ages out. That limits the amount of data available to analyze.
The second is that heat is a major driving force behind tire aging. Tires operating in Phoenix age a lot faster than tires operating in Minneapolis. So unless you are careful to account for ambient temperature, any data collected is going to have a lot of scatter.
In fact, the RMA (Rubber Manufacturers Association, now the US Tire Manufacturers Association), did an extensive study shortly after the Ford/Firestone thing to see what could be determined by looking at tires being scrapped. I forget how many places they looked at tires, but it was at least 5 different cities. They examined thousands of tires and cataloged everything they could find.
They could not pick up any discernable pattern - except to say that old tires tend to fail more often than new tires. The scatter on the data was HUGE!! - making it impossible to say anything precise about tire age. The discussion at the time was how there must be other factors involved and how could those factors be determined to sort the data out further.
That's why you will find tire manufacturers state a 10 year limit. Everyone who looked at the data could see that. But it was clear from the data that tires from AZ looked a lot worse, but how do you say something about that in a clear and unambiguous way?
And part of what added to the confusion was that certain brands used a rubber compound in their sidewall that resisted cracking - and that rubber compound had nothing to do with the critical area between the belts! That meant that the normal indicator of problems was not available in every brand.
Further, I looked at our company's data and it was clear that the desert southwest (AZ, NV, TX, CA) produced the vast majority of the failures - and it took a few years for those to appear.
Since I retired, I have been studying failure patterns of tires as reported on the internet, and it seems like tires on trailers have far more issues than tires on motorhomes. It's hard to sort out, but it looks like a combination of loading (Trailer tires are more heavily loaded than other types of tires) and the tire design (the internal construction). This somewhat correlates to the country of manufacture, but it also correlates to the lack of attention given to the design (internal construction) of ST tires versus LT tires - BUT - this is thoroughly confounded by the manufacturer (brand).
Put another way, LT tires were given a thorough look-see after the Ford/Firestone thing and all the major tire manufacturers changed construction, but I'm pretty sure ST tires weren't.
Now this adds fire to the ST vs LT tire debate as well has the Chinese vs US debate, but both of those debates ignores the fact that those things could change - AND - since we are looking at reported failures as our data, it is easy to overlook if the reports disappear - and that appears to be what is happening.
And that could mean a reset on the age debate.
