Tires and Passenger Vehicle Fuel Economy Informing Consumers, Improving Performance -- Special Report 286 (2006) / Chapter Skim
Currently Skimming:
6 Findings, Conclusions, and Recommendations
6 Findings, Conclusions, and Recommendations
Pages 123-136
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 123... ...
Rolling resistance not only differs among tires when they are new but also changes as tires are used and maintained. The findings in this study make it possible to approximate the effect of a plausible reduction in the average rolling resistance of replacement tires in the passenger vehicle fleet on vehicle fuel economy.
|
From page 124... ...
The overall effect of a reduction in rolling resistance on vehicle fuel economy will depend on a number of factors, including the underlying efficiency of the engine and driveline as well as the relative amounts of energy consumed by other factors, such as aerodynamic drag and vehicle accessories. For most passenger vehicles, a 10 percent reduction in rolling resistance will have the practical effect of improving vehicle fuel economy by about 1 to 2 percent.
|
From page 125... ...
Other tire features and design parameters affect rolling resistance as well, including tire mass, geometry, and construction type. About 80 percent, or 200 million, of the 250 million passenger tires shipped each year in the United States go to the replacement market, while the remaining 50 million are installed on new passenger vehicles as original equipment.
|
From page 126... ...
All else remaining constant, a vehicle equipped with a set of passenger tires having an average rolling resistance coefficient of 0.01 will consume about 1 to 2 percent less fuel than will a vehicle with tires having a coefficient of 0.011. Whether such a differential in fuel economy would be observed at all points in the lifetime of the two sets of tires will depend in large part on how their respective rolling resistance characteristics change with tire condition and tread wear.
|
From page 127... ...
Comparisons of the rolling resistance values of samples of new replacement radial tires sold today with those of radial tires sold 25 years ago show this progress. The lowest rolling resistance values measured in today's new tires are 20 to 30 percent lower than the lowest values measured among replacement tires sampled during the early 1980s.
|
From page 128... ...
Shorter tire wear life results in more scrap tires and in consumers spending more on tire replacement, both of which are undesirable. Consequently, tire companies and their material suppliers have invested in research and development to find ways to reduce rolling resistance with minimal adverse effects on tread wear.
|
From page 129... ...
Reducing rolling resistance saves fuel. If the average rolling resistance exhibited by replacement tires in the passenger vehicle fleet were to be reduced by 10 percent, motorists would save $12 to $24 per year in fuel expenses, or roughly $1.20 to $2.40 for every 1 percent reduction in average rolling resistance.
|
From page 130... ...
Calculations in this report suggest that each 1 percent reduction in tire wear life costs consumers about $1.20 more per year in added tire expenses because of more frequent tire replacement. Consequently, a shift in the kinds of tires purchased that has the effect of reducing average rolling resistance but also reducing the average life of replacement tires will cause higher tire expenditures, as well as larger numbers of scrap tires.
|
From page 131... ...
Specifically, Congress asked how lowering replacement tire rolling resistance would affect · Motor fuel use; · Tire wear life and the creation of scrap tires; · Tire performance characteristics, including those relevant to vehicle safety; and · Tire expenditures by consumers. Drawing on the study findings, the committee offers its assessment of the feasibility of reducing rolling resistance and its conclusions in
|
From page 132... ...
A tire's overall contribution to vehicle fuel consumption is determined by its rolling resistance averaged over its lifetime of use. A reduction in the average rolling resistance of replacement tires in the fleet can occur through various means.
|
From page 133... ...
Reductions in tread thickness, volume, and mass are among the means available to reduce rolling resistance, but they may be undesirable if they lead to shorter tire lives and larger numbers of scrap tires. Various tread-based technologies are being developed and used with the goal of reducing rolling resistance without significant effects on wear resistance.
|
From page 134... ...
Effects on Consumer Fuel and Tire Expenditures Reducing the average rolling resistance of replacement tires promises fuel savings to consumers that exceed associated tire purchase costs, as long as tire wear life is not shortened. A 10 percent reduction in rolling resistance can reduce consumer fuel expenditures by 1 to 2 percent for typical vehicles.
|
From page 135... ...
Until such a practical measure is developed, rolling resistance measurements of new tires can be informative to consumers, especially if they are accompanied by reliable information on other tire characteristics such as wear resistance and traction. Advice on specific procedures for measuring and rating the influence of individual passenger tires on fuel economy and methods of conveying this information to consumers is outside the scope of this study.
|
From page 136... ...
Motorists must be alerted to the fact that even small losses in inflation pressure can greatly reduce tire life, fuel economy, safety, and operating performance. A strong message urging vigilant maintenance of inflation must therefore be a central part of communicating information on the energy performance of tires to motorists.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.