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Old 08-07-2018, 10:11 AM   #11 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
I'm ignorant when it comes to the tire industry, but it seems a simple test as I suggest, with a dynamometer measuring power required to spin a certain speed under certain load and temperature conditions; you could pretty quickly get a rough estimate of efficiency.

Or does the problem have more to do with breaking in the tire so that it performs in a consistent way?
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Originally Posted by Stubby79 View Post
You'd think they'd be able to calculate it fairly closely with computer models, calculations based on tread design and material selection...

Yeah, it won't be perfect in the real world, but it ought to give an idea without the cost of testing every size of a particular tire.
If I recall correctly, NHSTA was insistent that a test be performed. They were not going to accept estimates. Given that a recall could be the end effect, the tire manufacturers objected - and the GAO (General Accounting Office) agreed, so the proposed rule was withdrawn.

The test isn't difficult and getting correlations between test sites was possible, but it does take time to do it - and since there are literally hundreds of makes and models of tires - and many sizes in each make and model, and each needed to be tested, the task is quite formidable.

If NHTSA had proposed using estimates - and I'm an advocate of that! - this probably wouldn't have been a problem.

What I find funny about this is that NHSTA already has procedures in place for treadwear ratings that allows for estimates - or more precisely stated: They only ask for the treadwear rating to be traceable back to the official test. That could be done with RR as well, but that's NOT what NHTSA was stating in their proposed rule - and they wouldn't commit off the record to allowing estimates or traceable ratings.

But as I said there was more than one problem, and one I didn't mention was how to display the result. NHTSA wanted to use RRF (Rolling Resistance Force) because smaller tires give smaller values and they thought that this would encourage people to buy smaller cars - while the tire manufacturers wanted to use RRC (Rolling Resistance Coefficient) because people don't buy cars based on the performance of the tires, but they DO buy replacement tires based on their performance and they argued that larger tires (with their better RRC values) would discourage people from buying tires with smaller load carrying capacities (which is what using RRF would appear to be better) and that was directionally safer (less risk of tire failure).

So I was hopeful that this month we would see a revised rule with reasonable expectations, but that is not to be.

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Old 08-07-2018, 11:34 AM   #12 (permalink)
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https://www.michelin.co.uk/tyres/lea...tyre-labelling

Who assigns the ratings to the EU tyres. They have ABC EFG for RR, A the best

"Save up to £110 or 80 litres of fuel over the life of the tyres. That’s for a car fitted with four A-rated tyres driving at 50mph – it uses 7.5% 1* less fuel than with G-rated tyres.
Results can vary with type of car or climatic conditions but the performance gaps are proven."

"1* Performance measured in accordance with the testing methods set by Regulation CE 1222/2009. European Commission’s Impact Assessment SEC (2008) 2860."
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Old 08-07-2018, 09:08 PM   #13 (permalink)
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Quote:
Originally Posted by roosterk0031 View Post
https://www.michelin.co.uk/tyres/lea...tyre-labelling

Who assigns the ratings to the EU tyres. They have ABC EFG for RR, A the best

"Save up to £110 or 80 litres of fuel over the life of the tyres. That’s for a car fitted with four A-rated tyres driving at 50mph – it uses 7.5% 1* less fuel than with G-rated tyres.
Results can vary with type of car or climatic conditions but the performance gaps are proven."

"1* Performance measured in accordance with the testing methods set by Regulation CE 1222/2009. European Commission’s Impact Assessment SEC (2008) 2860."
They are self assigned, just like the UTQG ratings and what was proposed previously for the US for rolling resistance. No difference there.

What is interesting is that they use RRC.

But in my search I found that there seemed to be little in the enforcement area. What was published wasn't policed in any effective way.

Back in 2016, there was a small campaign and they found quite a few violations, but only a few that were serious. However, there wasn't any report on what was done about the violations. Huge loophole!

That seems to be what is different between EU and the US. I know that NHTSA does do enforcement, however, they are reasonable to work with - BUT - for some reason, they didn't see fit to express this when they issued their first version of the rule.
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Old 06-10-2020, 08:52 AM   #14 (permalink)
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Time for an update:

According to this February 2020 report (https://www.transportation.gov/sites...t02072020r.pdf), a proposed rule for publishing rolling resistance of tires was supposed to be published March 30, 2020. That did not happen.

Is that the result of the current "Stay ay Home" orders? Don't know, but since NHTSA has kicked the can down the road repeatedly, I suspect not.

If a new report gets published (they seem to be published irregularly!), I'll let you know what it says.
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Old 06-10-2020, 09:34 AM   #15 (permalink)
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It's a pity they are dragging their feet. If the same tire is sold in Europe it should already have a label like this:

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Old 06-10-2020, 12:30 PM   #16 (permalink)
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The tires on my Insight came with the European C rating sticker still intact.
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Old 06-11-2020, 03:24 AM   #17 (permalink)
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I got a set of "LRR tires" that were euro "C" rated.
They killed the range on my leaf.
They got better after a few thousand miles.
Need up replacing them with new energy saver A/S tires. Those energy savers at 36psi appeared to be as efficient as the worn out ecopia tires at 44psi.
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Old 06-11-2020, 09:59 AM   #18 (permalink)
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Quote:
Originally Posted by oil pan 4 View Post
I got a set of "LRR tires" that were euro "C" rated.
They killed the range on my leaf.
They got better after a few thousand miles.
Need up replacing them with new energy saver A/S tires. Those energy savers at 36psi appeared to be as efficient as the worn out ecopia tires at 44psi.
There are a load of brands making euro "A" rated tyres suitable for the leaf.

Pirelli
Dunlop
Goodyear
Nokian
Hankook
Continental
Michelin

C rating is actually very average for a 16" tyre. No wonder they did not work very well having to haul 1.5 tonnes plus driver.

In sizes of 14" or less then C is as good as it gets.
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Old 06-12-2020, 07:48 AM   #19 (permalink)
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How is it possible that wider tires with the same rim size score better on rolling resistance according the EU tire label? For example, I can't imagine that 205/45 is more fuel efficient than 185/60. And yet the first gets an A label and the second gets a B.
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Old 06-12-2020, 08:00 AM   #20 (permalink)
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Quote:
Originally Posted by cr45 View Post
There are a load of brands making euro
C rating is actually very average for a 16" tyre. No wonder they did not work very well having to haul 1.5 tonnes plus driver.

In sizes of 14" or less then C is as good as it gets.
Needs some new super compound to get that A rating on little 14” tires

But then again large tires using the same unicorn farts would be AAA+ rated.


I wonder why Europe uses the D grade on heavy trucks but skips it on cars,
More dramatic, get a Flunk if you can’t achieve at least C+?

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