vSmartWay
Transport Partnership
U.S. ENVIRONMENTAL PROTECTION AGENCY
Energy
and
Fuel Savings
Gallons Saved
100 gallons
CO2 Savings
1.02 Metric tons
Increase in Fuel
Economy
NewMPG
6.04 mpg
Fuel Cost Savings
Maintaining Proper Tire Inflation Pressure
A Glance at Clean Freight Strategies
Maintaining proper tire inflation pressure can save tire maintenance costs
and improve fuel economy by nearly I percent, saving IOO gallons of fuel and
eliminating I metric ton of greenhouse gas emissions per year. Properly inflated
tires also have fewer punctures and a longer life expectancy.
What is the challenge?
When not properly inflated, tires flex more under load. This produces heat and increases roll-
ing resistance, which wastes fuel. Truck tires inflated 10 pounds per square inch (psi) below
recommended air pressure levels can reduce truck fuel economy between 0.5 percent and 1
percent.
Heat and stress from improper inflation soften and deflect tire components, causing faster
and more uneven wear, which shorten the life of the tire. Underinflated tires have more fre-
quent punctures, increasing the risk of tire failures that could lead to costly road service and
loss of revenue.
Despite the importance of proper tire inflation pressure, a recent survey of combination
trucks found that less than half the tires surveyed were within 5 percent of the recommended
inflation pressure. Another industry survey indicates only 8 percent of truck drivers check tire
pressure with a tire gage before each trip. One reason fleets may find it difficult to keep tires
properly inflated is that truck tires can lose up to 2 psi each month, even if the rim seal and
valve stems are tight. A fleet may not be able to inspect or monitor its trailer tires regularly
due to the fact that extended periods of time are spent away from service yards and because
trailers are interchangeable. This places greater responsibility for checking tire pressure onto
drivers.
What is the solution?
One way to prevent tire pressure underinflation is for fleets to have tire maintenance man-
agement systems in place to ensure that drivers and equipment maintenance personnel
check tire pressure at frequent intervals and fill tires that are underinflated. This can be made
easier by the use of electronic tire pressure monitoring systems that signal to drivers and
maintenance personnel when a tire becomes underinflated.
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1 Trucking companies
can contact tire manu-
facturers or their state or
national trucking associ-
ations for more informa-
tion about the benefits
of keeping tires properly
inflated.
2 Fleet operation
managers can consider
installing automatic
tire pressure inflation
systems on drive and
trailer tires to help
maintain proper tire
inflation pressure
while trucks are on the
road.
3 Interested fleets can
check with equipment
manufacturers and
truck and tire dealers
for more information on
ATI, nitrogen fill or other
technologies developed
to enhance tire mainte-
nance and ensure proper
tire inflation pressure.
SmartWay Transport | EPA420-F11-005 | www.epa.gov/smartway | 734-214-4767 | smartway_transport@epa.go
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Maintaining Proper Tire Inflation Pressure
Automatic tire inflation (ATI) systems monitor and continually adjust the level of pressurized air in tires, maintaining
proper tire inflation automatically while the truck is in motion. One ATI system uses the vehicle's own air-brake com-
pressor to supply air to all the tires. Once an ATI system is installed, it should not require any special attention from the
drivers. This eliminates the need to check tire pressure manually, which saves time and labor while ensuring consis-
tent and proper tire inflation.
There is some evidence that loss of tire inflation pressure can be slowed by using nitrogen gas instead of air to inflate
tires. While this method is not recommended as a substitute for regular checks of tire pressure, testing by the U.S.
Department of Transportation has shown that nitrogen inflation reduces the rate of pressure loss.
Savings and Benefits
ATI systems can not only extend tire life but truck fleets can also offer additional savings from reducing the risk of
expensive tire failure caused by underinflation. Installing an ATI system on a truck's drive and trailer axles costs up
to $800. For a typical long-haul combination truck, annual fuel savings could reach 100 gallons, saving $346 in fuel
costs and eliminating 1 metric ton of greenhouse gas emissions. Annual tire maintenance costs can also decrease.
The cost of installing an ATI system in a long-haul truck is generally recouped in just over 2 years through fuel and
maintenance cost savings.
There have been no scientific studies to document fuel savings obtained through the use of nitrogen inflation, but
anecdotal reports indicate some fleets are seeing benefits from this approach. One large national fleet reported to a
panel of the National Academy of Sciences that it observed a 1 to 1.5 percent reduction in fuel use after using a nitro-
gen inflation system. Additionally, nitrogen inflation systems typically remove oxygen and water from the inflation gas;
both oxygen and water can contribute to tire aging.
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SmartWay Transport | EPA420-F11-005 | www.epa.gov/smartway | 734-214-4767 | smartway_transport@epa.gov
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