Michelin champions tire rolling resistance

Tires have a large impact on vehicles' fuel economy. At an event in New York City last week, executives at Michelin tire said that after discounting engine and other losses, tire rolling resistance accounts for about 20 percent of the energy needed to power a car. Overall, Michelin figures that tires account for about 3 to 5 percent of the nation's CO2 emissions and about 9 percent of U.S. oil consumption.

In a country burning nearly 4 billion barrels of gasoline and diesel fuel per year for transportation, as the United States is, that's a lot of fuel going to turning tires. Doing the basic math, 3 percent of 4 billion barrels is about 120 million barrels a year. Rolling resistance varies with tire wear, condition, alignment, load, speed, inflation pressure, and road texture, so exact calculations are difficult to come by.

Jim Micali, president of Michelin North America, says that the company's next-generation Energy Saver tire can cut rolling resistance by a further 20 percent over its current line of low-rolling-resistance tires. Michelin expects that a 50-percent reduction in resistance is possible in the next 10 to 15 years. A 20-percent reduction in rolling resistance would be equivalent to a 3-percent savings in fuel consumption for drivers.

At the same time, the company turned on a Times Square billboard (in conjunction with similar ones in Berlin, Paris, and Shanghai) to track how many gallons of fuel the company says drivers have saved worldwide by using its current Energy series of high-mileage tires, compared with the industry average for rolling resistance. The number started out at 2,380,056,909 gallons, and it is increasing by 11.6 gallons per second. (See the latest numbers in the online green meter.)

In our recent new-car testing, we have seen that cars and trucks with low-rolling-resistance original equipment tires sometimes sacrifice grip. Some tire suppliers say some auto manufacturers put higher priority on low-rolling resistance over other performance criteria. In testing aftermarket all-weather tires, we have found that it's possible to get a very good performing tire with low-rolling resistance compared to other tire replacement tires. And Michelin says its upcoming line of low-rolling-resistance tires will save energy without shortening tread life or reducing grip.

The state of California is working on developing a rating for tire rolling resistance, which it plans to require tiremakers to print on the tire sidewalls starting in 2009. Meanwhile, to help consumers choose the appropriate replacement tires, the California Energy Commission is developing a complete database of all replacement tires marketed in the state. The database should be available in 2007 or 2008. Today, tires are required to have ratings printed on the sidewall for traction, tread life, and temperature.

Consumer Reports supports increasing consumer awareness of tire efficiency, which is why we test and provide rolling resistance ratings in our tire performance studies. Rolling resistance is one of many key performance attributes Consumer Reports tests as part of its tire ratings.

Giant billboards like the one in Times Square may help raise awareness of the problem to a small degree, although it omits savings by any other tiremakers' products. In the effort to be perceived as a "green" company, it is hard to miss the irony of using megawatts of electricity to deliver the message. Still, if the savings are that big for one brand, there are clearly more gallons to be saved across all brands that offer low-rolling resistance tires. CR recommends that consumers consider a lower rolling resistance tire as a tie-breaker between two or more models, but don't sacrifice the safety of good grip for low rolling resistance.   

--Eric Evarts

updated 7/16

Comments

[blanchard krogstad]

I found this on a tire website. I hope that CU follows up with both Michelin and Hankook's claims to see if they are based in fact:

"South Korea’s Hankook Tire Co. has developed an “ultra fuel efficiency tire” – the fx-Optimo – which, the tiremaker claims, “drastically maximizes fuel efficiency” by lowering rolling resistance as much as 25% without impacting other performance characteristics.

The company has spent five years and 10 billion won developing the new tire and has hinted that this release will form the basis of a “green strategy” that will target the hybrid vehicle market.

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.

The tiremaker plans to tackle the European market first, which is highly sensitive to fuel prices, as well as hybrid vehicle producers in Asia and elsewhere.

Hankook says it used a special rubber compound technology and tire structure design for the new product – the Hankook Hybrid System (HHS) – and will brand the fx-Optimo sidewalls with the HHS logo. Tread durability and lower rolling resistance comes from splitting silica particles into nano-sized pieces, Hankook says, and creating a more balanced mix with traditional carbon black."

[Bob Wilson]

Hi,

Your tire rating only shows a symbol for "best" rolling resistance for five tire models. Is there someway to get the numerical values for either the specific model tires or the ranges for the different grades?

The tires I am interested in are:
* Michelin X Radial
* Michelin Agility Touring
* Michelin Harmony
* Toyo 800 Ultra
* Sumitomo HTR T4

Thanks,
Bob Wilson

[christopher eastin]

Michelin is currently making these tires that help cut down on emissions and the claim that they don't sacrifice performance is true. they have tested this tire as written about in popular science.

[DH Lindsey]

Here is a wiki I found for more info on Rolling resistance coefficient (RRC).

Yes it is a wiki, which can be edited by anyone--take with a big grain of salt.

Hope this helps.