Tire rack wet stopping tests

JHZR2

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Whatever the conditions of those tests are, enerfy saver tyres are the worst in wet stopping, barring some extreme budgets occasionally.

Narrow non-energy saving tyres would stop that prius sooner.
Marginally. Of course a BRZ is going to have bigger more powerful brakes than the Prius, and the wider tires also may have better grip on dry pavement.

26C4488D-041B-4DC6-B87F-E2D1FF08E989.png
FD0F8DBE-B15C-4CF1-96B2-FB140A55E927.png


For further discussion, here are the pilot super sport tires I have on my 135i.

81049B84-7571-43E7-ADE3-95C5DD807FFF.png
665DCECA-7334-4B81-A9DC-96B972F6385F.png


So the narrow Michelin energy saver tires on a Prius stop better in the wet than the PSS on a BMW as well.
 
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Tire Rack has its own track, where they're been performing tests since 1995.

They may not follow industry procedure, as outlined above, but consistency and repeatability should not be an issue for the tests they do perform.

Tire testing is a PITA, and hard enough so that the car rags don't really do them any longer. And when they did do them, they didn't have the facilities, consistency, or regular cadence that TR has when doing them.
Why then are their tests results so varied? And they themselves say you can’t compare results between tests? The way tire rack says they do the tests is the easiest to replicate, as it’s just relative comparison of the 3-4 different tires in the test on that day…. I’m glad they do their testing but I think there is room for improvement, the wet braking example between the Prius and Toyota 86…. Something in their methods is a bit flawed to have results that varied?
 
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Missing part is "reference/standard tire" but it costs extra money and one does not sell them to regular people.

Krzys
 
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Why then are their tests results so varied? And they themselves say you can’t compare results between tests? .....he way tire rack says they do the tests is the easiest to replicate, as it’s just relative comparison of the 3-4 different tires in the test on that day…. I’m glad they do their testing but I think there is room for improvement, the wet braking example between the Prius and Toyota 86…. Something in their methods is a bit flawed to have results that varied?
In addition to the fact that Tire Rack doesn't use the SRTT (Standard Reference Test Tire) and doesn't adjust their values based on the SRTT's results, they also do on-vehicle tests - which means - particularly for braking tests - that the results might be influenced by the vehicle.

But I suspect the biggest difference is temperature. Allow me to give you some scenarios:

It's late March in northern Indiana. The Tire Rack guys have been getting ready for a test for the last month. They've done everything they could do that didn't involve the test track - fuel economy, ride, noise, etc. The only thing left is traction. They have to do the wet tests first, because the dry tests destroys the tires - and they have to wait until it is 45° because they can't operate the water sprayers below that temperature. - that lines may freeze up.

And today's forecast is for 45° Sure, the water will be a bit more viscous and that means the water is deeper and hydroplaning will be more of an issue - and sure, the tires will be colder and not as grippy - but it's the same for them all and the test at least is internally valid because they are testing at about the same time and temp.

Some months later - let's say late August - there's another test for the Tire Rack guys to run, and all they need is a clear day. Sure, it's going to be 90°F and the water will be thin, so the water depth is less so hyrdoplaning is less of an issue - and they are having trouble with dry spots because the water sprayers don't pump out water evenly and it evaporates, but they can just drive around them - and the tires will be more grippy - And that means the test is different than it was in March, - but it's the same of all of the tires being tested so the test will be internally valid, but it's certainly going to be different than it was in March.

On that same August day, at a test track in US southwest, a tire manufacturer is ready to conduct a wet traction test. They mounted the tires the day before, checked the water pipe flow to make sure they could control the water depth per the test spec, checked out the traction trailer for proper data pickup, so off they go. They start off with the SRTT - and get results that are expected, so they can conduct the next runs with confidence. In a couple of hours, they've done over a dozen different tires, so they end the test with another run of the SRTT - and again get expected results, so no reruns! They hate it when they get bad results from the SRTT, because that means they have to run the test again another time - and that means more mounting of tires, more expense.

The test crew sends the results to a statistician who adjusts the values per the procedure and forwards both the raw data and the adjusted data to the tire engineer who ordered the test. The tire engineer compares this test to one they conducted last year, and there's some differences in the raw data, but the adjustments made because of the SRTT makes those differences small. Even then there are some reversals, so the tire engineer reports to his management that fact when he publishes the results. Good thing they have other tests to help make some sense out of things.
 
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In addition to the fact that Tire Rack doesn't use the SRTT (Standard Reference Test Tire) and doesn't adjust their values based on the SRTT's results, they also do on-vehicle tests - which means - particularly for braking tests - that the results might be influenced by the vehicle.

But I suspect the biggest difference is temperature. Allow me to give you some scenarios:

It's late March in northern Indiana. The Tire Rack guys have been getting ready for a test for the last month. They've done everything they could do that didn't involve the test track - fuel economy, ride, noise, etc. The only thing left is traction. They have to do the wet tests first, because the dry tests destroys the tires - and they have to wait until it is 45° because they can't operate the water sprayers below that temperature. - that lines may freeze up.

And today's forecast is for 45° Sure, the water will be a bit more viscous and that means the water is deeper and hydroplaning will be more of an issue - and sure, the tires will be colder and not as grippy - but it's the same for them all and the test at least is internally valid because they are testing at about the same time and temp.

Some months later - let's say late August - there's another test for the Tire Rack guys to run, and all they need is a clear day. Sure, it's going to be 90°F and the water will be thin, so the water depth is less so hyrdoplaning is less of an issue - and they are having trouble with dry spots because the water sprayers don't pump out water evenly and it evaporates, but they can just drive around them - and the tires will be more grippy - And that means the test is different than it was in March, - but it's the same of all of the tires being tested so the test will be internally valid, but it's certainly going to be different than it was in March.

On that same August day, at a test track in US southwest, a tire manufacturer is ready to conduct a wet traction test. They mounted the tires the day before, checked the water pipe flow to make sure they could control the water depth per the test spec, checked out the traction trailer for proper data pickup, so off they go. They start off with the SRTT - and get results that are expected, so they can conduct the next runs with confidence. In a couple of hours, they've done over a dozen different tires, so they end the test with another run of the SRTT - and again get expected results, so no reruns! They hate it when they get bad results from the SRTT, because that means they have to run the test again another time - and that means more mounting of tires, more expense.

The test crew sends the results to a statistician who adjusts the values per the procedure and forwards both the raw data and the adjusted data to the tire engineer who ordered the test. The tire engineer compares this test to one they conducted last year, and there's some differences in the raw data, but the adjustments made because of the SRTT makes those differences small. Even then there are some reversals, so the tire engineer reports to his management that fact when he publishes the results. Good thing they have other tests to help make some sense out of things.
Do you think consumer reports uses a SRTT? They do allow direct comparisons in their test results, which I think is very useful in this time of all-season, all-weather and winter tires all performing similarly in some winter conditions. I am now cross shopping between tire type and probably more people are doing the same.
 
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most tire sellers want to sell costlier tires for MORE profits IMO so i always look as several sites + as many reviews as possible!!! costlier tires are usually better as they should be, BUT as noted + my experience the Mich MXV energy OE tires on my 2001 jetta $$$ were some worse i ever used next to cheep Kelly performance tires i put om my 64 olds cutlass
 
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Do you think consumer reports uses a SRTT? They do allow direct comparisons in their test results, which I think is very useful in this time of all-season, all-weather and winter tires all performing similarly in some winter conditions. I am now cross shopping between tire type and probably more people are doing the same.
I think they do NOT use the SRTT. They appear to conduct on-vehicle tests and the SRTT is a particular size and would only fit certain vehicles - plus they are expensive and on-vehicle tests would require 4 (perhaps 2?, certainly they could not do one.)

But I can think of 2 ways they could conduct their tests that would allow them to say the tests can be compared.
 
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I think they do NOT use the SRTT. They appear to conduct on-vehicle tests and the SRTT is a particular size and would only fit certain vehicles - plus they are expensive and on-vehicle tests would require 4 (perhaps 2?, certainly they could not do one.)

But I can think of 2 ways they could conduct their tests that would allow them to say the tests can be compared.

They were very proud of their test circuit during an open day a few years back.
They admitted to doing the pavement twice for wet testing as it did not have correct slope on first attempt.

They probably use a tire from previous test (the physically the same tire or the same model) to compare the runs.

Krzyś
 
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Why then are their tests results so varied? And they themselves say you can’t compare results between tests? The way tire rack says they do the tests is the easiest to replicate, as it’s just relative comparison of the 3-4 different tires in the test on that day…. I’m glad they do their testing but I think there is room for improvement, the wet braking example between the Prius and Toyota 86…. Something in their methods is a bit flawed to have results that varied?

Barry can (and has) offered his thoughts, and to me, serves as the ultimate authority on tire matters on this site.

The differences in the test results do bring valid questions, but it was important to point out that TR, contrary to speculation, does have established facilities, presumably a consistent methodology, and to be fair, notes the limitations of their testing, which should be read and interpreted accordingly.

AFAIK, those efforts aren't made by any other tire retailer, and they could probably sell just as many tires without spending that money on the program, or spending it on pure marketing efforts, so they also deserve at least some credit for that, even if it's not done to industry standards. And on that count, it's also important to understand the context, and limitations of industry standards like the UTQG ratings, or brake pad friction ratings, etc.

One must read and take into account all the sources of information, not just one, so it's nice to have something beyond user reviews (which have no control/consistency) or the occasional car rag test.
 
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when those tyres are no longer on the road? Maybe longer as new tyres get compared to the previous gen all the time.
Can appreciate that and wondered when I saw that test data on Tirerack the other day as an considering the Michelin energy saver for 2012 Prius-wal mart online has the h rated energy savers for 148 in 205/60/16 compared with 190 at Tirerack… when I saw the older study I wondered if Michelin has made changes through the years in that tire.
 
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Why then are their tests results so varied? And they themselves say you can’t compare results between tests? The way tire rack says they do the tests is the easiest to replicate, as it’s just relative comparison of the 3-4 different tires in the test on that day…. I’m glad they do their testing but I think there is room for improvement, the wet braking example between the Prius and Toyota 86…. Something in their methods is a bit flawed to have results that varied?
You can't compare tests which were carried out on different vehicles. There are variables such brake bias and brake pad.
 
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