Low-rolling resistance tires

Low-rolling resistance tires are tires which are designed to improve fuel efficiency of a car by minimizing the energy wasted as heat as the tire rolls down the road. Approximately 5–15% of the fuel consumed by a typical car may be to overcome to rolling resistance. [ [http://www.eere.energy.gov/afdc/vehicles/fuel_economy_tires_light.html Low Rolling Resistance Tires] (Website). Energy Efficiency and Renewable Energy, U.S. Department of Energy. Retrieved on 2007-08-11.] A 2003 California Energy Commission (CEC) preliminary study estimated that adoption of low-rolling resistance tires could save 1.5–4.5% of all gasoline consumption, but that current data were also insufficient to compare safety and other characteristics. [ [http://www.energy.ca.gov/reports/2003-01-31_600-03-001F-VOL1.PDF California State Fuel-Efficient Tire Report: Volume I] California Energy Commission, July 2003. Retrieved on 2007-08-11.] A database of much more complete data will be released by the CEC pending completion of an ongoing study. [http://www.energy.ca.gov/2006publications/CEC-600-2006-003/CEC-600-2006-003-FS.PDF Tire and Fuel Efficiency] California Energy Commission, June 2006. Retrieved on 2007-08-11.]

Measuring rolling resistance in tires

"Rolling resistance coefficient (RRC). The value of the rolling resistanceforce divided by the wheel load. A lower coefficient means the tires will use less energy to travel. The Society of Automotive Engineers(SAE) has developed test practices to measure the RRC of tires. Thesetests (SAE J1269 and SAE J2452) are usually performed on new tires.When measured by using these standard test practices, most new passenger tires have reported RRCs ranging from 0.007 to 0.014." [http://onlinepubs.trb.org/onlinepubs/sr/sr286.pdf "Tires and Passenger Vehicle Fuel Economy: Informing Consumers, Improving Performance -- Special Report 286."] , National Academy of Sciences, Transportation Research Board, 2006. Retrieved on 2007-08-11]

Standard equipment

Most hybrid vehicles are equipped with low-rolling resistance tires.Fact|date=June 2007

Auto manufacturers in the United States typically equip new vehicles with tires that have lower rolling resistance than their average after-market replacements, in order to meet Corporate Average Fuel Economy (CAFE) standards. [ [http://forums.tdiclub.com/showthread.php?t=111009 Low Rolling Resistance Tires...Which is Best? - TDIClub Forums ] ]

These include Conti Contact, Michelin Energy, and Goodyear Eagle LS tires.

Available tires

Some tires available in 2003 ranked by coefficient from lowest (least wasteful), according to the United States National Academy of Sciences Transportation Research Board Special Report 286 and the March 2003 Green Seal report on the topic [http://www.greenseal.org/resources/reports/CGR_tire_rollingresistance.pdf Green Seal Report] ] .

* 0.00615 Bridgestone B381 P185/70R14
* 0.00650 Michelin SYMMETRY P225/60R16
* 0.00683 Michelin TIGER PAW AWP P225/60R16
* 0.00700 Bridgestone DUELER H/T 113S P265/70R17
* 0.00709 Michelin RUGGED TRAIL T/A P285/70R17
* 0.00754 Michelin LTX A/S P255/65R17
* 0.00758 Goodyear INTEGRITY (OE) P225/60R16
* 0.00760 Bridgestone INSIGNIA SE 200 89S P195/65R15
* 0.00767 Michelin RUGGED TRAIL T/A P245/65R17
* 0.00780 Continental Ameri-G4S WS P235/75R15
* 0.00795 Michelin TPAW TOURING TR/SR P215/70R16
* 0.00810 Bridgestone DUELER H/T 104S P235/70R16
* 0.00813 Goodyear Invicta GL 235/75R15
* 0.00825 Continental ContiTouring Contact CH95 P205/55R16
* 0.00829 Michelin CROSS TERRAIN SUV P255/75R17
* 0.00833 Michelin PILOT PRIMACY 275/50R19
* 0.00850 Michelin ENERGY LX4 P225/60R16
* 0.00854 Michelin PILOT LTX P265/70R17
* 0.00855 Michelin ENERGY MXV4 PLUS 235/65R17

Here is a list of Consumer Report's tires that achieved their best rolling resistance rating. The tires at the top of the list are rated higher overall.
*Highly rated:
**All Season
**Michelin X Radial
**Michelin Agility Touring
**Michelin Harmony
**Toyo 800 Ultra
**Sumitomo HTR T4
*Middle rank
**Performance All Season
**Michelin Energy MXV4 Plus
**Continental ContiPremierContact H
*Least benefit
**All Season Ultra High Performance
**General Exclaim UHP
**Continental ContiExtremeContact

Below are the light duty tires (as reported by Consumer reports) achieving their best rolling resistance rating. Again, higher overall rated tires are closer to the top of the list.
*All-season
*Bridgestone Dueler H/T D684
*Michelin Cross Terrain
*Continental ContiTrac SUV
*BFGoodrich Radial Long Trail T/AFollowed by:
*All-terrain
*Continental ContiTrac TR

Comparison with conventional tires

Depending on the specific technique and materials used by the manufacturers, tire life may be as good as conventional tires, and traction may also be as good.

A Union of Concerned Scientists newsletter says "LRR tires also meet the same federal standards for treadwear, traction, and temperature resistance as regular tires." [ [http://www.ucsusa.org/publications/earthwise/sp04-earthwise-low-rolling-resistance-tires.html Earthwise: Updates from the Union of Concerned Scientists, Volume 6, Number 2, Spring 2004] ]

Regional Requirements

California has new rolling resistance requirements that go into effect in July 2008 [ [http://www.autobloggreen.com/2008/01/03/california-has-low-resistance-tire-laws/ California has low-resistance tire laws - AutoblogGreen ] ] . The law was passed in 2003 and the standards and reporting requirements were finalized in 2007.

Certifications

Passenger tires are tested for rolling resistance in order to obtain the German Blue Angel eco-label [http://books.nap.edu/openbook.php?record_id=11620&page=9 Tires and Passenger Vehicle Fuel Economy: Informing Consumers, Improving Performance -- Special Report 286 (2006) by Board on Energy and Environmental Systems (BEES)] ]

See also

* Low-energy vehicle
* Rolling resistance
* Fuel efficiency
* Blue Angel (certification)

References

External links

* [http://auto.howstuffworks.com/tire4.htm how tires support a car]

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