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Old 01-09-2019, 11:19 PM   #31 (permalink)
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I'm liking these michelin energy saver A/S tires.
More like energy saver AF.

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Old 01-10-2019, 07:57 AM   #32 (permalink)
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Quote:
Originally Posted by rmay635703 View Post
This discussion makes me believe RR needs to be listed numerically on each tire pulled at its rated weight and inflation pressure.

I thought RR ratings were law

What happen
US regulations were first published in the 2010 timeframe, but were withdrawn for technical reasons. The latest is that new regulations are supposed to be published June 2019.

If you want more detail about what the technical problems were that caused the first set of regulations to be withdrawn, say so and I'll explain. Warning: It will be a bit long as the issues are complex.
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Old 01-10-2019, 08:49 AM   #33 (permalink)
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Oh do tell.
My best friend is a mechanical engineer that works for Yokohama tire. We talk about tire stuff all the time.
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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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Old 01-10-2019, 09:09 AM   #34 (permalink)
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There were 3 issues that needed to be resolved if a regulation was to be put in place:

1) What test to perform. There are several different tests, but it turns out that tires can be compared using a single point test – quick and easy.

2) How to correlate different testing facilities. They decided on assigning a value to the SRTT (Standard Reference Test Tire), then adjusting the results based on those values. The SRTT is a commonly used reference where tests can vary by – say – temperature or testing surface. It’s an old Uniroyal tire that Michelin makes using certified materials and they test to assure the tire hasn’t changed from batch to batch (and if it has, how to adjust the results.)

3) How to express the result so that it is easy for the average consumer to understand. This is where the technical issues got in the way.

First, rolling resistance varies by tire size. So a way needed to be developed to deal with that. NHTSA (National Highway Traffic and Safety Administration) wanted EVERY size to be tested in EVERY tire line for EVERY tire manufacturer. USTMA (US Tire Manufacturers Association) pointed out that it would take 3 years of 24/7 testing to achieve that result – and during those 3 years no research could be done – and that just wasn’t going to fly.

Second, NHTSA wanted to use RRF (Rolling Resistance – Force) in order to push consumers to buy smaller cars. The USTMA pointed out that consumers wouldn’t buy cars based on the tire’s rolling resistance even if they had that information. They would use the fuel economy values published by the vehicle manufacturers – AND that consumers would be better served if RRC (Rolling Resistance Coefficient = RRF divided by the test load) was what was published.

Then there was the issue of how to display this information – which kind of got lost in the 2 points above. One proposal was a traffic light (Red/Yellow/Green) kind of indicator without the actual values being published. Another was a bar graph showing where a particular tire was compared to the best and worst tire – but that meant that any new max or min values would result in obsoleting the previous published graphs.

In the end the proposed rule was withdrawn to work out the 2 issues mentioned above – the size issue and the RRF vs RRC. This was in 2010. In the meantime, there was this HUGE airbag recall that occupied most of the technical resources of NHTSA, so the Rolling Resistance regulations weren’t worked on – until recently.

The publication date has been pushed back repeatedly – and I expect it to be pushed back some more based on the current administration's attitude towards regulations.
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Old 07-03-2019, 03:58 PM   #35 (permalink)
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Update of Rolling Resistance Regulations for the US:

As predicted, the date for publishing the rules has been pushed back. It is now slated for March. 2020 (from June 2019.)
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Old 07-03-2019, 04:28 PM   #36 (permalink)
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CapriRacer: I just checked your web pages. They are now bookmarked for reference. It will take me a while to get through them, but I'm determined. Thank you for the information and supporting references for the information.
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Old 07-04-2019, 04:34 PM   #37 (permalink)
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Sub - '84 Chevy Diesel Suburban C10
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camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
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90 day: 124.63 mpg (US)
Thanks: 179
Thanked 2,497 Times in 1,952 Posts
Can't say I'm surprised.
I was expecting it to be dropped or pushed back again.

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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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