How to find fuel efficient LRR (low rolling resistance) tires

[tnthub]

<div class='quotetop'>QUOTE(DocVijay @ Jul 2 2006, 08:17 AM) [snapback]280046[/snapback]</div>

Also, in going from a relatively low rolling resistance tire to a much higher resistance tire (and wider and heavier too) I went from 52 mpg to 51.3 mpg. That is a 1.35% drop.
[/b]

I am not going to disagree.

That said, in my experience at the drag strip, simple cloud cover can account for a .02 variance in elapsed time, and the calculated density altitude can easily make 1-2 tenths of second difference over 1/4 mile. Couple that with variable such as warm up time, traffic flow, stoplights, passengers or not, the wait at the ATM or coffee window, rain or dry, hot or cold and I would expect a 1-5 percent variance in the course of normal driving regardless of tire changes.

As I said, I am not disagreeing but I would contend that so many factors weigh into an accurate calculation that outside of a test facility I do not believe that I would personally be able to quantify the results of a tire change with that level of accuracy.

[theorist]

Should I have titled the topic -- LRR tires: are they evil or should they be required?

I never imagined this would become such a polarized, heated topic. The truth is I don't care what tires other people use or what cars other people drive. I started this topic not to tell anyone what to what tires they should use, but to help the drivers who _want_ LRR tires to find find them. I feel that ranting about how evil LRR tires are is a bit like coming to a topic on how to find or buy a Prius and ranting about how pointless hybrids are or how all non-hybrid cars should be outlawed. Still, diverse opinions are always welcome, and certain.

Does anyone have any tips on how to find rolling resistance coefficients for different tires?

[tomdeimos]

<div class='quotetop'>QUOTE(theorist @ Jul 2 2006, 04:13 PM) [snapback]280194[/snapback]</div>

Should I have titled the topic -- LRR tires: are they evil or should they be required?

I never imagined this would become such a polarized, heated topic. The truth is I don't care what tires other people use or what cars other people drive. I started this topic not to tell anyone what to what tires they should use, but to help the drivers who _want_ LRR tires to find find them. I feel that ranting about how evil LRR tires are is a bit like coming to a topic on how to find or buy a Prius and ranting about how pointless hybrids are or how all non-hybrid cars should be outlawed. Still, diverse opinions are always welcome, and certain.

Does anyone have any tips on how to find rolling resistance coefficients for different tires?
[/b]

I think I saw something about Wayne Brown's simulator having some more tire data when the for sale version comes out.

And I can't wait for CA to force the numbers to be labeled on the tires.

If you have some tires to test I expect it is pretty easy to do a comparison. I can think of two methods.
On a level surface measure the force needed to roll the car forward at a steady walking pace.

The other is to find a small hill followed by a flat area and measure the distance you can coast.

I expect quantifying it all into an accurate number is quite possible but I have no idea how. But in the cases mentioned virtually all of the losses would be from the tires. There would be some from the gears turning, but I think these losses happen more when there is a load.

I just measured my tires with the mfd read out driving steady speed on level road, right before and after my switch. I have gone back to the oem tires this year to use them up, but could not repeat the measurement because the big switch to ethanol additive happened about the same time.

I can't wait to get back to my greener tires, and plan to get the better ones the next time I need them that can be run up to 50 lbs.

[tnthub]

I apologize if I degraded this thread. It was certainly not my intent. In most automatic cars, even an efficient driveline may have up to a 20% loss by the time a chassis dyno can measure the rwp.

Conceptually I have no problem labelling for rolling resistance at all. I think the labels would be beneficial if they were not misused. I do not believe it should be a requirement, but I think it would be a great selling point and marketing pitch for any tire branding company wanting to pick up market share. However with all the regulations currently in place in the tire industry, and the safety ramifications of reduced rolling resistance, and the different road surfaces that taxpayer buld roads utilize, I don't know what to think.

I want people to be able to select lower rolling resistance tires just as I can select higher rolling resistance tires. I believe the wear ratings will reasonably follow the rolling resistance pattern of stickier tires wearing out sooner so I am unsure how to really quantify rolling resistance. A good stuicky tire will have more rolling resistance on an asphalt track but much less on a dirt road or in the rain so how can that be quantified so the average driver may make an informed decision?

[tnthub]

From the SEMA website:

Tire Fuel Efficiency: A report published by the Transportation Research Board recommends that the government collect and share information on how tires affect the fuel efficiency of cars and light trucks. NHTSA will now consider implementing its recommendations and conducting further research. The report estimates that about 200 million replacement tires are in use in the United States and that consumers spend about $20 billion annually replacing worn-out tires. The Board concludes that it is technically and economically feasible to reduce rolling resistance by up to 10%. The Board acknowledged that correct tire inflation, misalignment and misbalancing are major contributors to rolling resistance. The Board also cautioned that a rolling-resistance program may be undesirable if it leads to shorter tire lives and larger numbers of scrap tires. Two year ago, California passed a rolling-resistance law that included a SEMA amendment exempting limited production tires (15,000 or less annually) and other specialized tires. California officials are expected to being drafting and implementing regulations in 2007. SEMA remains concerned that tire fuel-efficiency initiatives may distract motorists from important issues such as maintaining proper tire-inflation pressures. The programs may also dissuade consumers from buying tires that have improved performance, handling or appearance features, based solely on a rolling resistance rating.

[tnthub]

I found this here: http://www.tirereview.com/?type=art&id=5822

Hankook reports that, compared to existing tires of the same size, the fx-Optimo boasts 25% lower rolling resistance, for a maximum 3% improvement in fuel efficiency. In addition, the tire is said to exhibit enhanced wet braking and control characteristics compared to existing tires. And, according to Hankook, the tire delivers treadwear comparable to existing tires.

[Frank Hudon]

<div class='quotetop'>QUOTE(theorist @ Jun 29 2006, 08:18 PM) [snapback]278936[/snapback]</div>

I've got to get out of Lexington.

and ration gasoline with each person being limited to 10 gallons a week? :P
[/b]

now how am I going to burn that much? 40 gallons a month... oh I see, sell the excess to the SUV drivers! ya I'm ok with that now.

[theorist]

Here's the most comprehensive and trusted research report on fuel efficient tires and rolling resistance that I've found to date. This is a 110 page report from the National Academies. Don't worry. It has a has an executive summary, a detailed table of contents, and you can search to find what interests you.

Tires and Passenger Vehicle Fuel Economy: Informing Consumers, Improving Performance -- website

Report - pdf

Raw data on recent tires - pdf

[tnthub]

I started reading last night and I'm still reading. That is a lot of information.

[bluetwo]

I'm glad we're not stuck on the idea that soft rubber and good dry traction compounds are at one end of the rolling resistance spectrum while hard rubber low traction high mileage tires are at the other.

There are so many other things to consider it's just not smart to try and simplify it.

I can't remember if this link was posted here because I've read so many, so I'll just put it up anyway: Alternative Fuels and Advanced Vehicles Data Center: Low Rolling Resistance Tires