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Old 09-15-2015, 03:25 PM   #31
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Initial testing before the tire is put into full production and then the follow-up DOT certification tests required by the FMVSS.

Ahh, thought that was what you were thinking.

DOT does not run certification tests.

It is the tire manufacturer's responsibility to "certify" that all tires made would be capable of passing the minimum test requirements as published by FMVSS. Now as to pre-production testing, that should be based on statistical analysis of the variation of test results observed by the tire company on it's own products.

The DOT requirements do not allow for variation. They say 100% of tires must be able to pass the tests. Tire companies know that test results do in reality vary.
If you have a volume of data that tells you that your product varies by x amount then a competent company should allow for that variation such that statistically speaking say 99.95% would pass. However I would not be surprised to learn that some companies cut corners and are satisfied with a prediction that say 60% or 80% will pass as they are betting that no one will check.
They also know that if they have no warranty and the RV community will not file enough complaints to get the attention of DOT, there will never be a compliance test run by DOT so the company can "get away with" making less than 1st class quality products.
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Old 09-15-2015, 03:29 PM   #32
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China testing tires Later RJD
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Old 09-15-2015, 09:07 PM   #33
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Originally Posted by Tireman9 View Post
Ahh, thought that was what you were thinking.

DOT does not run certification tests.

It is the tire manufacturer's responsibility to "certify" that all tires made would be capable of passing the minimum test requirements as published by FMVSS. Now as to pre-production testing, that should be based on statistical analysis of the variation of test results observed by the tire company on it's own products.

The DOT requirements do not allow for variation. They say 100% of tires must be able to pass the tests. Tire companies know that test results do in reality vary.
If you have a volume of data that tells you that your product varies by x amount then a competent company should allow for that variation such that statistically speaking say 99.95% would pass. However I would not be surprised to learn that some companies cut corners and are satisfied with a prediction that say 60% or 80% will pass as they are betting that no one will check.
They also know that if they have no warranty and the RV community will not file enough complaints to get the attention of DOT, there will never be a compliance test run by DOT so the company can "get away with" making less than 1st class quality products.
I know why and when tire testing is done. As an engineer you should have faith in them or tried to change the process years ago.

All of the major tire manufacturers, foreign and domestic, have some form ISO quality program in progress all the time.
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Old 09-16-2015, 11:58 AM   #34
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I know why and when tire testing is done. As an engineer you should have faith in them or tried to change the process years ago.

All of the major tire manufacturers, foreign and domestic, have some form ISO quality program in progress all the time.

I think you might be a bit optimistic.
Having been involved in ISO quality audits I can assure you that there are many companies that do not bother with ISO type quality standards.
Now you did say "major" so I guess that depends on what you meant by "major".
The other reality is that even with a "Major' manufacturer there may be some plants that are not ISO certified as none of that plant's products get shipped to vehicle manufacturer that requires ISO.

A quick test would be to ask your FR dealer if FR is ISO certified or if FR requires ISO quality from their vendors. I bet you will see a blank stare and hear crickets chirping.
If you are told "yes" then you might ask why they don't display ISO certification certificate.
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Old 09-20-2015, 08:25 PM   #35
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Does towing wear the rear tires out on your TV faster? I have 20,000 miles on my Ram 2500 and the rear tires have twice the amount of wear as the front tires. They are getting close to the tread-wear indicators. The factory tires are Firestone.
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Old 09-20-2015, 11:15 PM   #36
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Does towing wear the rear tires out on your TV faster? I have 20,000 miles on my Ram 2500 and the rear tires have twice the amount of wear as the front tires. They are getting close to the tread-wear indicators. The factory tires are Firestone.
Without having some specific information IMO a major contributor to both fuel economy and tire wear is based on driving style.

Too often people drive big vehicles or when towing and seem to expect similar response in the big vehicle as they are use to in their car.

My basis for this opinion comes from mpg when I was towing my 26' enclosed trailer with a Camaro and race support tools & equipment and the mpg from driving my last two Class-C motorhomes. In all three cases I could see a 10% difference in fuel economy based both on fill-up gallons as well as electronic engine monitor readings between different members of my race crew who were driving or between myself and the DW in the case of the motorhomes.

it doesn't take too much difference in the level and rate of acceleration to give this difference. Tire wear is also affected by acceleration rates. You don't have to be spinning tires to see harder acceleration that translates to faster tire wear. It is also true that when driving a large pick-up with no load makes it very easy to spin a tire and each "chirp" can translate into the equivalent of hundreds of miles wear.
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Old 09-21-2015, 10:40 AM   #37
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Looks like Michelin tires get the but to obtain a quite ride which do you go with M/S or A/T?
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Old 09-21-2015, 11:33 AM   #38
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A/T are usually a more aggressive tread pattern which translates to more noise.
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