Tire Pressures and Sustainability:
The Economic and Environmental Effects of Under-Inflated and Over-Inflated Tires
at Williams College
Sam Baldwin
GEOS 206
Professor Dethier
18 May 2010
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Introduction:
Global awareness concerning the effects of tire pressure on fuel efficiency and
tread wear accompanies periods of increased fuel costs as well as environmental
movements towards more sustainable automobile practices. As gas prices were rising in
2006, for example, tire manufacturer associations were promoting more sustainable tire
maintenance procedures to facilitate cost cutting for car owners (Jones, 2006). Similarly,
environmentally conscious individuals tend to monitor the tire pressures of their vehicles
more often in order to reduce their carbon dioxide emissions. Although the environmental
and economic effects of maintaining recommended tire pressures in all of the vehicles
owned by Williams College are minor relative to the effects of other behavioral or material
changes that the college might consider, the establishment of a campus-wide policy to
require tire pressure maintenance sets a precedent among colleges and universities and
encourages conscientiousness among college affiliates regarding their personal
environmental footprints.
The best available data suggest that Williams College owns 77 vehicles, which
implies that the college is responsible for 308 tires on the road at any given time. The
impact of 308 tires seems minimal; however, both under-inflated and over-inflated tires
contribute to higher vehicle maintenance costs (economic and environmental) in addition
to increased CO
2
emissions. Under-inflated tires become flatter along the surface in
contact with the road, increasing their internal heat and rolling resistance. Consequently,
under-inflated tires suffer from excessive and accelerated tread wear particularly along
their edges (see Figures 1 and 2a), which reduces their life expectancies by as much as
25%, (Air, 2010) and they suffer from a reduction in fuel efficiency by as much as 3.3%
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(Keeping, 2001). Tire over-inflation causes uneven tread wear particularly along the
center of the tire (see Figure 2b) and increases the possibility of explosive decompression
(Tire, 2010).
a. b.
Figure 1: a. Illustrates the profile of a properly inflated tire, showing the correct amount of tread
contact with the road. b. Depicts the profile of an under-inflated tire, demonstrating how under-
inflation increases tread contact with the road as well as how under-inflation generates
disproportionate tread wear. (http://www.nitrogentiremachine.com/proper_tire_inflation.htm).
a. b.
Figure 2: a. Exemplifies the increased tread wear along the edges of an under-inflated tire. b.
Illustrates the increased tread wear along the center of an over-inflated tire.
(http://www.nitrogentiremachine.com/proper_tire_inflation.htm).
This project studies the impact of Williams College vehicles’ tire pressures on CO
2
emissions, fuel costs, and sustainability issues while addressing the feasibility of instituting
a policy requiring improved tire maintenance practices.
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Method:
Using the spreadsheet outlining the years, makes, models, identification
information, and departments of Williams College vehicles provided by Tim Reisler
(Assistant Director for Administrative Services at Facilities) as a guide for locating the
vehicles on campus, I tested the tire pressures of all 4 tires on 66 out of 77 Williams
College vehicles with a dial tire pressure gauge. (Note: I was unable to locate the
remaining 11 vehicles.) Afterward, I calculated the overall difference between the
recommended tire pressures for each vehicle and actual, observed tire pressures for each
vehicle. From the driver’s side doorjamb, I recorded the recommended tire pressures for
all of the unlocked vehicles; for the locked vehicles, I estimated the recommended tire
pressures based on similar makes and models. Typically utilizing used car sales websites,
I located and recorded the U.S. Environmental Protection Agency (EPA) estimated fuel
economies for each vehicle.
Based on the U.S. Department of Energy statistic that under-inflated tires reduce
gas mileage by 0.3% for every 1 pound per square inch (psi) decrease in pressure of all 4
tires (Keeping, 2001), I calculated the percentage change in fuel economy and found the
adjusted fuel economy for each under-inflated vehicle (in miles per gallon). Then, using
2007 data from Katie White’s project and assuming that each department currently drives
the same number of miles per year despite potential changes in fleet size, I calculated the
number of miles driven within each department and divided that figure by the number of
vehicles in the department. Using the resulting mileage figures with the EPA estimated
and adjusted fuel economy figures as computed above, I finally calculated the number of
gallons of gas used by each vehicle under recommended tire pressure conditions as well as
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adjusted tire pressure conditions and, assuming that gas costs $2.75 per gallon, calculated
the amount of money spent on gas each year under both conditions. In order to ascertain
how many pounds of CO
2
are emitted under each of the conditions, I used the statistic from
the EPA maintaining that 19.4 pounds of CO
2
are emitted for every gallon of gas
consumed (Emission, 2005). Furthermore, with regard to tread wear, I used the statistic
that for every 10% decrease in tire inflation, tire life decreases by 10% (Tire Inflation).
For over-inflated tires, I quantitatively examined the data in spreadsheet form,
qualitatively analyzed the effect of over-inflation on tire life expectancy, and researched
the resulting negative impacts on sustainability.
Data:
The tire pressure measurements reveal that only 1 out of 66 Williams College
vehicles tested had the proper tire pressure overall; however, even that vehicle
demonstrated inconsistencies in recommended and actual pressures within each tire.
Moreover, 23 vehicles had under-inflated tires overall (see Appendex A), and 37 vehicles
had over-inflated tires overall (see Appendex B). (Note: 5 of the vehicles tested were too
problematic to include and analyze: 1 vehicle had a flat tire, and 4 vehicles had
inaccessible valves.)
Under-Inflation Data and Analysis:
Vehicles with under-inflated tires overall experienced a range of percentage loss in
fuel economy from 8.325% to 0.225% (see Appendix A and Figure 3). The differences
appear to be negligible when viewing each vehicle independently; however, when
considering the total miles per gallon lost for all under-inflated vehicles, the difference
seems more significant (see Figure 4).
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Change in Fuel Economy for Under-Inflated Tires
10
15
20
25
30
35
40
45
50
SIERRA SIERRA EXPRESS F150 ECONOLINE F350 TRK F150 F350 E350 RANGER F150 ASTRO SIENNA AVEO SIENNA PRIUS ASTRO ASTRO SAFARI PRIUS SIENNA ECONOLINE
GMC GMC CHEVROLET FORD FORD FORD TOYOTA FORD FORD FORD FORD FORD CHEVROLET TOYOTA CHEVROLET TOYOTA TOYOTA CHEVROLET CHEVROLET GMC TOYOTA TOYOTA FORD
2005 2002 2004 1999 2001 2001 1988 2007 2006 2004 2008 2005 2004 2009 2005 2004 2005 2005 2003 2005 2007 2008 2006
Vehicles (Year, Make, Model)
Fuel Economy (MPG)
EPA Estimated MPG
Adjusted MPG
Figure 3: Graph depicts fuel economy (in mpg) for each vehicle under EPA estimated conditions
and observed, under-inflated conditions. Notice how the difference appears to be slight for each
vehicle.
Total Fuel Economy Under Both Conditions
Conditions
Total Fuel Economy Per Year (MPG)
Series1
Figure 4: Graph illustrates total fuel economy among all under-inflated vehicles for recommended
conditions and under-inflated conditions. Notice how the difference appears to be more
considerable when comparing total values.
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I calculated that vehicles with under-inflated tires overall use 182.58 extra gallons
of gas each year (see Appendices C and D), which, at $2.75 per gallon, costs Williams
College approximately $502.10 extra each year (see Appendices E and F). Again,
considering each vehicle by itself diminishes the overall differences; that is, the differences
in the number of gallons of gas and the amount in dollars spent on gas each year appear to
be minor when examining individual vehicles but look more significant when considering
their annual totals. Furthermore, assuming that 19.4 pounds of CO
2
are emitted for every
gallon of gas consumed (Emission, 2005), I calculated that Williams College emits
3,542.05 extra pounds of CO
2
each year due to under-inflated tires (see Appendix G).
With regard to the excess tread wear resulting from under-inflated tires and using
the statistic that tire life expectancy decreases by 10% for every 10% of under-inflation
(Emission, 2005), I conclude that Williams College tires (in the most extreme cases of
under-inflation) are losing up to 8% of their life expectancies. Assuming that tires last
nearly 80,000 miles now (Tire Aging, 2010), this percentage loss indicates that under-
inflated tires are being disposed of up to 6,400 miles sooner than they would be under
recommended tire pressure conditions.
In terms of under-inflation as a departmental problem, the tires on the 3 vehicles
used by OIT are all considerably under-inflated. I reason that this observation is a
reflection of a departmental issue pertaining to vehicle maintenance. Similarly, 16 of the
36 vehicles used by Facilities that I tested suffer from under-inflation; however, my policy
recommendations do not require further inquiry into the sources of these departmental
observations.
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Over-Inflation Data and Analysis:
Out of the 66 vehicles tested at Williams College, 37 had over-inflated tires overall.
The degree of over-inflation for each of these vehicles ranged from 1 pound per square
inch to 96 pounds per square inch, and the total amount of over-inflation was 1,096 pounds
per square inch among the 37 over-inflated vehicles combined (see Appendix H).
Vehicles with over-inflated tires are not analyzed quantitatively because of a lack
of available data and resources; however, their negative environmental impacts are evident.
First, the life expectancies of over-inflated tires are reduced as a result of excess tread
wear. Extrapolating from the 10% decrease in life expectancy for every 10% reduction in
inflation, I speculate that over-inflated tires suffer even more extreme tread wear because
the surface area of the center of the tread, which contacts the road more exclusively for
over-inflated tires, is most likely smaller. That is, since the tire contacts the road only
along the center of the tread when it is over-inflated, and the center of the tread has less
surface area than the entire tread, over-inflated tires must suffer from increased contact in a
more concentrated area and thus more severe tread wear than under-inflated tires or tires
with recommended pressures. Hence, I conjecture that the life expectancy of over-inflated
tires most likely decreases by more than 10% for every 10% increase in inflation. Again,
assuming that tires last nearly 80,000 miles (Tire Aging, 2010), a 15% reduction in life
expectancy would result in a loss of 12,000 miles per tire; a 20% reduction in life
expectancy would result in a loss of 16,000 miles per tire; and so on. With drivers forcing
tires into retirement earlier than necessary, more and more tires are piling up in landfills
and contributing to the problem of unsustainable tire disposal methods.
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According to Discover magazine, in the United States alone, 300 million tires are
discarded every year. An average castoff tire weighs 22.5 pounds and produces
approximately 2 gallons of fuel in addition to other combustible carbon compounds when
burned. These used tires are extremely flammable and have been responsible for massive
fires, including the 1998 devastating fire in San Joaquin Valley during which 7 million
tires burned for two and a half years (Gugliotta, 2008). Approximately 55,000 gallons of
runoff oil are unleashed into the environment for every 1 million tires ignited (Tire Fires,
2010); hence, approximately 385,000 gallons of runoff oil were released in the San Joaquin
Valley fire. Moreover, tire fires pollute the air with emissions including polycyclic
aromatic hydrocarbons, benzene, styrene, phenols, and butadiene (Tire Fires, 2010). Large
tire dumping wastelands also contribute to the spread of infectious diseases as they are
inhabited by vermin and conveniently cater to mosquitoes as desirable breeding grounds
(Gigliotta, 2008).
Discussion and Recommendations:
Although the environmental and economic effects of under-inflated tires at
Williams College are noticeable, they are less severe than similar effects generated by
numerous other sources. Addressing tire pressure through policy at Williams, though,
would set a precedent among other colleges and universities, and it would help spread
awareness to individuals about the negative externalities and monetary losses associated
with improperly inflated tires. Rather than trying to solely enforce a top-down style policy
that might make vehicle users or particular departments feel targeted (i.e. OIT), I would
recommend that the college arrange a “tire pressure awareness celebration” day in which
the college gives out tire pressure gauges and information about the negative externalities
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and safety hazards associated with improper tire pressures. On that day, Williams could
institute its policy to require vehicle users to check tire pressures when filling up their
vehicles with fuel. By making this transition about awareness rather than strict
enforcement, vehicle users are less likely to feel overwhelmed and more likely to share the
statistics relating to the importance of maintaining proper tire pressures with their families
and friends.
Moreover, I recommend that a future student in GEOS 206 examine tire disposal at
Williams and relate it to both worldwide tire recycling progress and problems. The
percentage of used tires being recycled in the United States has risen from virtually 0% in
1990 to 30% in 2005 (Gugliotta), marking a promising movement toward more sustainable
means of tire disposal. In 1992, processors began grinding up used tires and converting
them into sidewalks, playground surfaces, and basketball courts. Now, ground-up, used
tires are backfilling and insulating new roads, which enhances the roads’ “springiness” and
makes them longer lasting (Gugliotta, 2008). A follow-up project by a future student
could investigate local contributions to these innovative disposal techniques.
For now, Williams College should focus on spreading awareness about the cheap
and easy ways to reduce CO
2
emissions and save money at the gas pumps while setting an
example through its own actions. Maintaining recommended tire pressures in college and
other vehicles is essentially a behavioral issue; checking tire pressures at the gas station
should hardly be an inconvenience for any driver. The payoffs for each driver are minor,
but, as this study shows, they tend to add up over a number of vehicles.
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References:
Works Cited:
“Air Pressure—Correct, Underinflated, and Overinflated.” Tire Rack. 2010. 13 May 2010.
<http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=1>.
“Emission Facts: Average Carbon Dioxide Emissions Resulting From Gasoline and Diesel
Fuel.” U.S. Environmental Protection Agency. Feb. 2005. 14 May 2010.
<http://www.epa.gov/oms/climate/420f05001.htm>.
Gugliotta, Guy. “A New Source of Green Energy: Burning Tires?” Discover. 12 Feb.
2008. 14 May 2010. <http://discovermagazine.com/2008/feb/new-source-of-green-
energy-burning-tires>.
Jones, Roland. “Tire Upkeep Can Boost Safety, Fuel Economy.” MSNBC. 3 May 2006. 14
May 2010. <http://www.msnbc.msn.com/id/12517107/>.
“Keeping Your Car in Shape.” www.fueleconomy.gov. 2001. 09 May 2010.
<https://www.fueleconomy.gov/feg/maintain.shtml>.
“Proper Tire Inflation.” Nitrogen Tire Inflation Systems. 14 May 2010.
<http://www.nitrogentiremachine.com/proper_tire_inflation.htm>.
“Tire Aging—Part #1.” Tire Rack. 2010. 13 May 2010.
<http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=138>.
“Tire Fires.” U.S. Environmental Protection Agency. 24 Feb. 2010. 14 May 2010.
<http://www.epa.gov/solidwaste/conserve/materials/tires/fires.htm>.
“Tire Inflation.” AA1Car. 14 May 2010. <http://www.aa1car.com/library/tirepres.htm>.
“Tire.” Wikipedia. 11 May 2010. 14 May 2010. <http://en.wikipedia.org/wiki/Tire>.
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Appendices:
Appendix A: Data Table: Vehicles with (overall) under-inflated tires sorted by percentage
decrease in fuel economy. Note: DS-F, DS-R, PS-F, and PS-R refer to driver’s side and
passenger’s side front and rear tires.
Year
Make
Model
Recommended
PSI (Front, Rear)
in lbs
EPA Estimated
MPG
DS-F
(lbs)
DS-R
(lbs)
PS-F
(lbs)
PS-R
(lbs)
Overall
Difference
(lbs)
Percentage
Decrease
Adjusted
MPG
2005
GMC
SIERRA
65, 65
13
37
38
37
37
-111
8.325
11.92
2002
GMC
SIERRA
65, 65
11
41
32
40
40
-107
8.025
10.12
2004
CHEVROLET
EXPRESS
55, 55
14
34
33
34
35
-95
7.125
13
1999
FORD
F150
45, 45
14
30
37
33
21
-59
4.425
13.38
2001
FORD
ECONOLINE
55, 55
13
56
55
55
25
-29
2.175
12.72
2001
FORD
F350
55, 55
12
46
51
47
51
-25
1.875
11.775
1988
TOYOTA
TRK
35, 35
11
28
30
27
31
-24
1.8
10.802
2007
FORD
F150
45, 45
12
43
45
28
43
-21
1.575
11.81
2006
FORD
F350
55, 55
12
50
52
50
50
-18
1.35
11.838
2004
FORD
E350
55, 55
13
55
54
42
53
-16
1.2
12.84
2008
FORD
RANGER
40, 40
16
37
37
36
35
-15
1.125
15.82
2005
FORD
F150
45, 45
12
39
44
40
43
-14
1.05
11.87
2004
CHEVROLET
ASTRO
38, 38
14
31
36
35
36
-14
1.05
13.85
2009
TOYOTA
SIENNA
35, 35
17
32
32
32
30
-14
1.05
16.82
2005
CHEVROLET
AVEO
30, 30
23
28
25
28
26
-13
0.975
22.78
2004
TOYOTA
SIENNA
35, 35
17
31
32
34
32
-11
0.825
16.86
2005
TOYOTA
PRIUS
35, 32
48
33
30
29
32
-10
0.75
47.64
2005
CHEVROLET
ASTRO
38, 38
14
38
35
35
34
-10
0.75
13.9
2003
CHEVROLET
ASTRO
38, 38
14
34
35
39
35
-9
0.675
13.91
2005
GMC
SAFARI
36, 36
12
34
34
34
35
-7
0.525
11.94
2007
TOYOTA
PRIUS
35, 32
48
32
32
33
32
-5
0.375
47.82
2008
TOYOTA
SIENNA
35, 35
17
32
37
32
35
-4
0.3
16.95
2006
FORD
ECONOLINE
55, 55
13
49
60
48
60
-3
0.225
12.97
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Appendix B: Data Table: Vehicles with (overall) over-inflated tires sorted by overall difference in
PSI. Note: DS-F, DS-R, PS-F, and PS-R refer to driver’s side and passenger’s side front and rear
tires.
Year
Make
Model
Recommended
PSI (lbs)
EPA Estimated
MPG
DS-F
DS-R
PS-F
PS-R
Overall
Difference
2000
FORD
F150
45, 45
14
45
45
45
46
1
2006
DODGE
GRAND
CARAVAN
35, 35
17
36
36
35
35
2
2003
CHEVROLET
ASTRO
38, 38
14
40
38
40
37
3
2002
CHEVROLET
ASTRO
38, 38
14
38
40
41
39
6
2004
HONDA
CIVIC
35, 32
48
34
32
36
38
6
2006
Dodge
GRAND
CARAVAN
35, 35
17
35
39
36
37
7
2007
TOYOTA
HIGHLANDE
R/HYBRID
32, 32
27
35
34
32
35
8
2006
FORD
ECONOLINE
55, 55
13
55
57
57
60
9
2004
GMC
SAVANA
55, 55
11
45
65
41
60
9
2008
TOYOTA
PRIUS
35, 33
48
35
37
39
37
12
2002
GMC
SAFARI
36, 36
12
42
39
40
38
15
2005
CHEVROLET
ASTRO
38, 38
14
44
42
40
42
16
2004
CHEVROLET
G1500
38, 38
15
43
43
42
42
18
2005
CHEVROLET
AVEO
30, 30
23
35
35
34
35
19
2004
TOYOTA
SIENNA
35, 35
17
40
40
39
41
20
2006
FORD
E-350
55, 55
14
58
64
57
64
23
2001
DODGE
CARAVAN
35, 35
17
42
41
41
40
24
CHEVROLET
AVEO
30, 30
23
36
36
37
36
25
2005
TOYOTA
SIENNA LE
35, 35
17
42
45
40
40
27
GMC
SAFARI
36, 36
12
41
46
43
42
28
2003
FORD
F450
70, 75
12
78
82
78
80
28
2007
GMC
SAVANNA
55, 55
11
62
62
62
62
28
2007
TOYOTA
SIENNA
35, 35
17
38
42
45
46
31
2009
Chevrolet
EXPRESS
55, 55
14
53
72
53
74
32
2008
TOYOTA
SIENNA
35, 35
17
43
44
42
45
34
2005
TOYOTA
CAMRY
32, 32
18
43
39
42
39
35
2006
GMC
SAVANA
55, 55
11
62
63
64
66
35
2009
Chevrolet
EXPRESS
55, 55
14
54
75
56
76
41
2007
Ford
ECONOLINE
E250
55, 55
13
66
67
63
67
43
2008
GMC
SAVANA
55, 55
11
55
79
52
78
44
2004
GMC
SAVANA
55, 55
11
59
75
60
75
49
2004
GMC
SAVANA
55, 55
11
62
74
65
68
49
2004
GMC
SAVANA
55, 55
11
60
72
61
77
50
2006
GMC
SAVANA
55, 55
11
75
64
73
62
54
2008
DODGE
SPRINTER
60, 60
26
68
79
70
78
55
2005
FORD
F350
55, 55
12
70
76
71
77
74
2009
FORD
E350
55, 55
14
78
80
80
78
96
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Appendix C: Graph illustrates the number of gallons of gas used by vehicles with observed under-
inflation under recommended and under-inflated conditions each year. Notice how the difference
appears to be negligible for each vehicle.
Number of Gallons Used Per Year Under Recommended and Under-Inflated
Conditions
0
500
1000
1500
2000
2500
2005 GMC Sierra (OIT)
2002 GMC Sierra (Facilities)
2004 Chevrolet Express (OIT)
1999 Ford F150 (Facilities)
2001 Ford Econoline (Facilities)
2001 Ford F350 (Facilities)
1988 Toyota Truck (Facilities)
2007 Ford F150 (Facilities)
2006 Ford F350 (Facilities)
2004 Ford E350 (Dining)
2008 Ford Ranger (Facilities)
2005 Ford F150 (Facilities)
2004 Chevrolet Astro (OIT)
2009 Toyota Sienna (Security)
2005 Chevrolet Aveo (Facilities)
2004 Toyota Sienna (Facilities)
2005 Toyota Prius (Facilities)
2005 Chevrolet Astro (Facilities)
2003 Chevrolet Astro (Facilities)
2005 GMC Safari (Facilities)
2007 Toyota Prius (Facilities)
2008 Toyota Sienna (Security)
2006 Ford Econoline (Facilities)
Vehicle (Year, Make, Model)
# of Gallons Used
Gallons
Adjusted Gallons
Appendix D: Graph shows the total number of gallons of gas consumed by vehicles with observed
under-inflation under recommended and under-inflated conditions each year. Notice how the
difference looks more substantial and significant when considering totals.
Number of Gallons Consumed Under Recommended and Under-Inflated
Conditions
12500
12550
12600
12650
12700
12750
12800
Recommended Conditions Under-Inflated Conditions
Conditions
Number of Gallons Consumed Per Year
Series1
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Appendix E: Graph shows the amount of money (in dollars) spent on gas each year for vehicles
with observed under-inflation under recommended and under-inflated conditions (assuming that
gas costs $2.75 per gallon). Notice how the differences appear to be rather insignificant for each
vehicle.
Dollars Spent on Gas Per Year Under Recommended and Under-Inflated
Conditions
0
1000
2000
3000
4000
5000
6000
7000
2005 GMC Sierra (OIT)
2002 GMC Sierra (Facilities)
2004 Chevrolet Express (OIT)
1999 Ford F150 (Facilities)
2001 Ford Econoline (Facilities)
2001 Ford F350 (Facilities)
1988 Toyota Truck (Facilities)
2007 Ford F150 (Facilities)
2006 Ford F350 (Facilities)
2004 Ford E350 (Dining)
2008 Ford Ranger (Facilities)
2005 Ford F150 (Facilities)
2004 Chevrolet Astro (OIT)
2009 Toyota Sienna (Security)
2005 Chevrolet Aveo (Facilities)
2004 Toyota Sienna (Facilities)
2005 Toyota Prius (Facilities)
2005 Chevrolet Astro (Facilities)
2003 Chevrolet Astro (Facilities)
2005 GMC Safari (Facilities)
2007 Toyota Prius (Facilities)
2008 Toyota Sienna (Security)
2006 Ford Econoline (Facilities)
Vehicle (Year, Make, Model)
Amount of Money Spent Per Year (Dollars)
Price
Adjusted Price
Appendix F: Graph illustrates the total amount of money spent on gas each year for vehicles with
observed under-inflation under recommended and under-inflated conditions (assuming that gas
costs $2.75 per gallon). Notice that the differences look more significant when comparing totals.
Money Spent on Gas Under Both Conditions
31200
31300
31400
31500
31600
31700
31800
31900
32000
Recommended Conditions Under-Inflated Conditions
Conditions
Dollars Spent on Gas Per Year
Series1
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Appendix G: Graph depicts the amount of CO
2
emitted each year by vehicles with observed
under-inflation under recommended and under-inflated conditions (assuming that 19.4 pounds of
CO
2
are emitted for every gallon of gas consumed).
Amount of Carbon Dioxide Emitted Under Both Conditions
242000
243000
244000
245000
246000
247000
248000
249000
Recommended Conditions Under-Inflated Conditions
Conditions
Amount of Carbon Dioxide (pounds)
Series1
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Appendix H: Data Table: Vehicles with (overall) over-inflated tires sorted by overall difference in
pounds per square inch between recommended conditions and observed, over-inflated conditions.
Note: DS-F, DS-R, PS-F, and PS-R refer to driver’s side and passenger’s side front and rear tires.
Year
Make
Model
Recommende
d PSI (lbs)
EPA Estimated
MPG
DS-F
DS-R
PS-F
PS-R
Overall
Difference
(PSI)
2000
FORD
F150
45, 45
14
45
45
45
46
1
2006
DODGE
GRAND
CARAVAN
35, 35
17
36
36
35
35
2
2003
CHEVROLET
ASTRO
38, 38
14
40
38
40
37
3
2002
CHEVROLET
ASTRO
38, 38
14
38
40
41
39
6
2004
HONDA
CIVIC
35, 32
48
34
32
36
38
6
2006
Dodge
GRAND
CARAVAN
35, 35
17
35
39
36
37
7
2007
TOYOTA
HIGHLANDE
R/HYBRID
32, 32
27
35
34
32
35
8
2006
FORD
ECONOLINE
55, 55
13
55
57
57
60
9
2004
GMC
SAVANA
55, 55
11
45
65
41
60
9
2008
TOYOTA
PRIUS
35, 33
48
35
37
39
37
12
2002
GMC
SAFARI
36, 36
12
42
39
40
38
15
2005
CHEVROLET
ASTRO
38, 38
14
44
42
40
42
16
2004
CHEVROLET
G1500
38, 38
15
43
43
42
42
18
2005
CHEVROLET
AVEO
30, 30
23
35
35
34
35
19
2004
TOYOTA
SIENNA
35, 35
17
40
40
39
41
20
2006
FORD
E-350
55, 55
14
58
64
57
64
23
2001
DODGE
CARAVAN
35, 35
17
42
41
41
40
24
CHEVROLET
AVEO
30, 30
23
36
36
37
36
25
2005
TOYOTA
SIENNA LE
35, 35
17
42
45
40
40
27
GMC
SAFARI
36, 36
12
41
46
43
42
28
2003
FORD
F450
70, 75
12
78
82
78
80
28
2007
GMC
SAVANNA
55, 55
11
62
62
62
62
28
2007
TOYOTA
SIENNA
35, 35
17
38
42
45
46
31
2009
Chevrolet
EXPRESS
55, 55
14
53
72
53
74
32
2008
TOYOTA
SIENNA
35, 35
17
43
44
42
45
34
2005
TOYOTA
CAMRY
32, 32
18
43
39
42
39
35
2006
GMC
SAVANA
55, 55
11
62
63
64
66
35
2009
Chevrolet
EXPRESS
55, 55
14
54
75
56
76
41
2007
Ford
ECONOLINE
E250
55, 55
13
66
67
63
67
43
2008
GMC
SAVANA
55, 55
11
55
79
52
78
44
2004
GMC
SAVANA
55, 55
11
59
75
60
75
49
2004
GMC
SAVANA
55, 55
11
62
74
65
68
49
2004
GMC
SAVANA
55, 55
11
60
72
61
77
50
2006
GMC
SAVANA
55, 55
11
75
64
73
62
54
2008
DODGE
SPRINTER
60, 60
26
68
79
70
78
55
2005
FORD
F350
55, 55
12
70
76
71
77
74
2009
FORD
E350
55, 55
14
78
80
80
78
96