Interesting piece about the tire industry and LRR tires

http://www.tirebusiness.com/article/20141204/NEWS/141209953/for-mpg-gains-tire-makers-deliver-consumers-shrug" onclick="window.open(this.href);return false;

Good read. Thanks.

It says for every 10% improvement in LRR you get a 1% improvement in MPG. Hmm.

And the Kia Soul EV is using a "Super" LRR tire, with 10% improvement.

Can't wait for the "Super, Super" LRR tires.

But glad the industry is focusing more on Improvements. Used to be it was very hard to get information on the topic.

Hmm who knew less friction between two surfaces lowered resistance to movement, just not isolated to one direction heh. I should get infinite mileage this winter as long as I go in a straight line with no stops and can get going.

I would have liked to have this data when I replaced my OE tires last July:

...Five years ago, the National Highway Traffic Safety Administration proposed introducing a national standard to gauge low-rolling resistance, to be used as a consistent consumer guide, similar to EPA fuel economy ratings. The implementation of that standard is still pending.

California regulators also have proposed creating a low-rolling-resistance guide, but that plan has stalled...

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http://www.tirebusiness.com/article/20141204/NEWS/141209953/for-mpg-gains-tire-makers-deliver-consumers-shrug" onclick="window.open(this.href);return false;

Are Nexen CP 671 available aftermarket yet?

Anyone tried them on a LEAF?

...The tires introduced on Kia Motors America's new electric Soul — Nexen CP 671 Classe Premiere — are being marketed as “super-low-rolling-resistance” tires.

Steve Kosowski, manager for long-range strategy at Kia, said the tires are a step beyond what other auto makers have been introducing in the past couple of years.

Manufactured by Nexen Tire Corp., the new "supers" reduce enough friction to contribute 3 to 5 miles of extra driving range for the battery-powered car. The Soul boasts a battery range of 93 miles, positioning it above the EV-segment leader Nissan Leaf, which claims an 84-mile range...

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edit-LRRs here for $88.

Wonder if they are as "Super" LRR as the Soul's OE?
http://www.tirerack.com/tires/TireSearchResults.jsp?tireIndex=0&autoMake=Nissan&autoYear=2011&autoModel=Leaf&autoModClar=SL&width=205%2F&ratio=55&diameter=16&sortCode=44950&skipOver=true&minSpeedRating=H&minLoadRating=S&tab=All" onclick="window.open(this.href);return false;

One thing the article fails to mention is that the improvement in overall drag brought by LRR tires drops by the square of the speed as aerodynamic drag becomes the prevalent source of total drag at higher speeds. Thus, consumers who spend most of their time at freeway speeds will see far less benefit from LRR tires in efficiency but will constantly be aware of the decreased traction and handling and other compromises that the LRR design brings... This will cause many to question the value of LRR and opt for something else at tire replacement time. This is one of the reasons why I dumped the Ecrapias and went to the Michelin MXV4s...

LRR doesn't [necessarily] mean lower friction. Rather, it means the way the tyre comes into rolling contact with the ground is less likely to cause block shifting and counter-loads across the contact patch. LRR still usually rate highly on the grip performance grades too.

Any loss of friction capability of a LRR should be the same variabilities of grip you get between any tyre manufacturers, or grades of tyre. It should simply mean there are fewer parasitic losses by design of the block, side-walls, plies and compound.

Good article, I had not considered the interplay of the CAFE rules, manufactuers and the replacement tire decisions.

Anyone seen any studies/information in efforts to build LRR roads? I wonder if this is taken into account when highways are resurfaced....

Slow1 said:

Good article, I had not considered the interplay of the CAFE rules, manufactuers and the replacement tire decisions.

Anyone seen any studies/information in efforts to build LRR roads? I wonder if this is taken into account when highways are resurfaced....

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I can only hope. Maybe Macadam and poorly-covered Chip Seal will become a thing of the past. If you've ever bicycled any significant distance on rough "chip seal" roads you know first-hand how much energy it sucks from you. It's hell on tire wear too.

I find it entertaining that the average person expected 5mpg to 10mpg improvement from getting a LRR tire. Shows that people really are just ignorant of science. Considering on average they are getting low 20's mpg, to say they want 25% to 50% improvement is ridiculous.

2k1Toaster said:

I find it entertaining that the average person expected 5mpg to 10mpg improvement from getting a LRR tire. Shows that people really are just ignorant of science. Considering on average they are getting low 20's mpg, to say they want 25% to 50% improvement is ridiculous.

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I put Ecopia's on my Prius, went from getting 55 mpg to 65 mpg at 60 mph. They replaced Kumo super high performance tires. 5 mpg is 10% on this car and that is what I expected, I got double that. I am very happy with the LRR tires. If they last 40k miles they will be free.

What contribution did 'observer bias' play, I wonder.

There are few measures more likely to be biased than fuel consumption figures.

donald said:

What contribution did 'observer bias' play, I wonder.

There are few measures more likely to be biased than fuel consumption figures.

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I don't think there was any observer bias. How can miles driven divided gallons used be biased?

pchilds said:

donald said:

What contribution did 'observer bias' play, I wonder.

There are few measures more likely to be biased than fuel consumption figures.

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I don't think there was any observer bias. How can miles driven divided gallons used be biased?

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Extremely easily. You put on newer tires, or you fill up with "better gas" or all sorts of things and your mileage improves. Could just be that while looking for good mileage, you are more likely to drive more efficiently.

I have a Prius, and a Prius C, and we have other hybrids in our family. You are not going to get a 10% improvement from LRR tires. You can easily get that by not being as bad of a driver. But that is not the tires, that's the human.

Yep. As 2k says, driving style. Just simple, plain repeatability kicks in too, unless you run with precise driving styles and conditions over many many miles.

In fact, in my real hypermiling days, I would get a +-4% variation, day to day, with no other variables in. I had a conversation with a friend who actually homologates vehicles for a VM and he said exactly the same, an 8% top-bottom variation was what he had to deal with. Interesting our numbers came out the same.

EVs seem more consistent. So perhaps the variations are due to things we don't notice like pressure and humidity, and/or that ICE engines are like us as breathing warm things that don't always work the same way every day!

Perhaps an alignment was done when tires were replaced? If really bad I bet an alignment issue could cost you 10%...

2k1Toaster said:

You are not going to get a 10% improvement from LRR tires.

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I easily lost 10% going from old Ecopias to new RoadHugger GT Ecos (Kumho Ecowing KH30). Others have seen worse with other tires. And these are supposedly LRR tires. I ran the data and efficiency went from ~210 Wh/mi to ~250 Wh/mi initially, are slowly improving to about ~235 Wh/mi after 2k miles so far, so still 10% worse, though admittedly it's a bit cooler now.

drees said:

2k1Toaster said:

You are not going to get a 10% improvement from LRR tires.

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I easily lost 10% going from old Ecopias to new RoadHugger GT Ecos (Kumho Ecowing KH30). Others have seen worse with other tires. And these are supposedly LRR tires. I ran the data and efficiency went from ~210 Wh/mi to ~250 Wh/mi initially, are slowly improving to about ~235 Wh/mi after 2k miles so far, so still 10% worse, though admittedly it's a bit cooler now.

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Cooler and new tires. You can't compare them that way because what you are measuring, or "running the data on", is an incomplete set.

2k1Toaster said:

Cooler and new tires. You can't compare them that way because what you are measuring, or "running the data on", is an incomplete set.

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Look, I'm not the only one who's noticed a significant difference with non-Ecopia tires. Pretty much everyone who stuck with Ecopia tires could not tell a difference between old and new tires. Check this thread: http://www.mynissanleaf.com/viewtopic.php?f=31&t=16282" onclick="window.open(this.href);return false; TickTock lost about 15% going to MXV4 tires.

Everyone else noticed at least a 10% hit that maybe decreased to 5% at best depending on the tire. I can tell you that historically I have not seen any significant difference in summer/winter driving. Certainly within 5%. It just doesn't get that cold here (today it was ~65F while commuting - earlier - could have ranged between 70-85F).

Regardless, my point was the claim that "you're not going to get a 10% better efficiency from LRR tires" is simply not true. It's quite easy to get 10% better efficiency from tires, depending on how bad the non-LRR tires are. Stick on some sporty summer tires and I bet you don't even get close.

Spot the switch in tires below. Can't plot more data as the commute changed. Moving average is over 10 data points.

drees said:

2k1Toaster said:

Regardless, my point was the claim that "you're not going to get a 10% better efficiency from LRR tires" is simply not true. It's quite easy to get 10% better efficiency from tires, depending on how bad the non-LRR tires are. Stick on some sporty summer tires and I bet you don't even get close.

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This is true in my experience. We replaced the tires on my wife's subaru with Ecopias and she noticed 15-20% improvement. Admittedly the tires that we replaced had significantly more aggressive tread...