the effects ofooffof inflation gas on tire …...the effects of inflation gas on tire laboratory...
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THETHETHETHE EFFECTSEFFECTSEFFECTSEFFECTS OFOFOFOF INFLATIONINFLATIONINFLATIONINFLATION GASGASGASGAS ONONONON TIRETIRETIRETIRE
LABORATORYLABORATORYLABORATORYLABORATORY TESTTESTTESTTEST PERFORMANCEPERFORMANCEPERFORMANCEPERFORMANCE
AAAAUTHORUTHORUTHORUTHOR:::: JJJJAMES AMES AMES AMES MMMMACACACACIIIISAACSAACSAACSAAC
DOTDOTDOTDOT ---- NHTSANHTSANHTSANHTSA
CCCCOOOO----AAAAUTHORUTHORUTHORUTHORSSSS::::
LLLLARRY ARRY ARRY ARRY EEEEVANSVANSVANSVANS
JJJJOHN OHN OHN OHN HHHHARRISARRISARRISARRIS
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The
Effe
cts
of In
flatio
n G
as
on T
ire L
abor
ator
y T
est
Per
form
ance
Jam
es D
. Mac
Isaa
c Jr
., U
SD
OT
-N
HT
SA
Larr
y E
vans
& J
ohn
Har
ris, T
rans
port
atio
n R
esea
rch
Cen
ter,
Inc.
Ed
Ter
rill,
Ph.
D.,
Akr
on R
ubbe
r D
evel
opm
ent L
abor
ator
y, In
c.
Pre
sent
ed a
t IT
EC
200
8A
kron
, OH
Sep
tem
ber
17, 2
008
Nitr
ogen
Infla
tion
of
Pne
umat
ic T
ires
�In
flatio
n of
tire
s w
ith N
2ga
s is
pre
sum
ed to
be
bene
ficia
l. H
owev
er, t
here
are
a w
ide
varie
ty o
f cl
aim
s an
d co
unte
r-cl
aim
s:•
Bet
ter
infla
tion
pres
sure
ret
entio
n•
Low
er r
ollin
g re
sist
ance
•B
ette
r tr
eadw
ear
•Lo
wer
run
ning
tem
pera
ture
s•
Bet
ter
tire
dura
bilit
y•
Less
moi
stur
e•
Etc
.
Nat
iona
l Hig
hway
Tra
ffic
Saf
ety
Adm
inis
trat
ion
�N
HT
SA
Tra
ffic
Saf
ety
Fac
ts, 2
006*
•In
200
6, th
ere
wer
e an
est
imat
ed 5
,973
,000
pol
ice-
repo
rted
traf
fic c
rash
es, i
n w
hich
:–
42,6
42 p
eopl
e w
ere
kille
d–
2,57
5,00
0 pe
ople
wer
e in
jure
d–
4,18
9,00
0 cr
ashe
s in
volv
ed p
rope
rty
dam
age
only
•A
n av
erag
e of
117
peo
ple
died
eac
h da
y in
mot
or
vehi
cle
cras
hes
in 2
006
—on
e ev
ery
12 m
inut
es•
Mot
or v
ehic
le c
rash
es a
re th
e le
adin
g ca
use
of d
eath
for
ever
y ag
e fr
om a
ges
2 th
roug
h 34
•F
rom
199
4 to
200
4, N
HT
SA
est
imat
es th
at a
bout
400
fa
talit
ies,
ann
ually
(~
1% o
f tot
al m
otor
veh
icle
fata
litie
s),
may
be
attr
ibut
ed to
tire
failu
res
of a
ll ty
pes
*NH
TS
A T
raffi
c S
afet
y F
acts
, 200
6 D
ata,
DO
T H
S 8
10 8
09, N
HT
SA
’s N
atio
nal C
ente
r fo
r S
tatis
tics
and
Ana
lysi
s, U
pdat
ed M
arch
200
8
NH
TS
A T
estin
g of
Tire
s w
ith
Nitr
ogen
Infla
tion
�N
HT
SA
re-
dire
cted
tire
s fr
om o
ther
tire
pr
ogra
ms
to a
ddre
ss fo
ur b
asic
que
stio
ns:
•Is
ther
e a
syst
emat
ic a
nd q
uant
ifiab
le d
iffer
ence
in th
e in
flatio
n pr
essu
re lo
ss r
ate
(IP
LR)
of ti
res
whe
n in
flate
d w
ith g
ases
of v
aryi
ng n
itrog
en to
oxy
gen
ratio
s?•
Are
any
obs
erve
d di
ffere
nces
in IP
LR u
nifo
rm a
mon
g tir
es, o
r ar
e th
ey r
elat
ed to
var
iabl
es s
uch
as in
itial
in
flatio
n pr
essu
re, o
r tir
e de
sign
and
com
posi
tion?
•A
re th
ere
dire
ct e
ffect
s of
infla
tion
gas
com
posi
tion
on
the
rolli
ng r
esis
tanc
e of
tire
s?•
Are
ther
e di
ffere
nces
in ti
re d
urab
ility
per
form
ance
afte
r ac
cele
rate
d ag
ing
rela
ted
to th
e ni
trog
en-t
o-ox
ygen
ra
tio?
Tes
ting
�T
wen
ty-f
ive
pass
enge
r or
ligh
t tru
ck ti
re
mod
els
wer
e in
flate
d w
ith:
•S
hop
air
with
air
line
drye
r•
Dry
N2
gas
from
94
to 9
9% p
urity
–In
itial
pur
ge a
nd r
efill
use
d
•G
as c
ompo
sitio
n m
easu
red
at th
e be
ginn
ing
and
end
of te
st
�T
ires
wer
e te
sted
for:
•In
flatio
n pr
essu
re lo
ss r
ate
•La
bora
tory
rol
ling
resi
stan
ce•
Roa
dwhe
el e
ndur
ance
afte
r ov
en a
ging
•M
ater
ial p
rope
rtie
s
Tire
Infla
tion
Pre
ssur
e Lo
ss
�U
nder
-infla
ted
tires
are
a s
igni
fican
t pr
oble
m•
Acc
ordi
ng to
a N
HT
SA
stu
dy, 2
7% o
f pas
seng
er
cars
and
32%
of l
ight
truc
ks h
ave
at le
ast o
ne
tire
that
is s
ubst
antia
lly u
nder
infla
ted*
–“O
pera
ting
a ve
hicl
e w
ith s
ubst
antia
lly u
nder
-infla
ted
tires
can
res
ult i
n a
prem
atur
e tir
e fa
ilure
, suc
h as
in
stan
ces
of tr
ead
sepa
ratio
n an
d bl
owou
ts, w
ith th
e po
tent
ial f
or a
loss
of c
ontr
ol o
f the
veh
icle
. U
nder
-in
flate
d tir
es a
lso
shor
ten
tire
life
and
incr
ease
fuel
co
nsum
ptio
n.”
**
*Tir
e P
ress
ure
Spec
ial S
tudy
@ h
ttp:/
/ww
w.n
htsa
.dot
.gov
/peo
ple/
ncsa
/
**U
.S. T
rans
port
atio
n Se
cret
ary
Nor
man
Y. M
inet
a@
htt
p://
ww
w.d
ot.g
ov/a
ffai
rs/n
htsa
4601
.htm
Tire
Infla
tion
Pre
ssur
e Lo
ss
�T
ires
lose
infla
tion
gase
s co
ntin
uous
ly, s
ince
ru
bber
com
poun
ds a
re p
erm
eabl
e to
gas
m
olec
ules
and
loss
es e
xist
thro
ugh
tire/
whe
el/v
alve
inte
rfac
es�
Tub
eles
s tir
es r
equi
re a
n in
nerli
ner
com
poun
d w
ith lo
w p
erm
eabi
lity
to li
mit
the
loss
of
infla
tion
�T
he A
ST
M F
1112
-06
test
mea
sure
s th
e st
atic
lo
ss o
f inf
latio
n ga
s fr
om a
tire
ove
r tim
e•
Dat
a is
rep
orte
d as
% lo
ss /
mon
th
AS
TM
F11
12-0
6 In
flatio
n P
ress
ure
Loss
Rat
e (I
PLR
)�
Min
imum
sam
ple
of 2
tire
s pe
r m
odel
�C
lean
pai
nted
ste
el (
pref
erre
d) w
heel
or
othe
r m
ater
ial t
hat h
as b
een
leak
che
cked
�R
im s
ize
per
Tire
& R
im A
ssoc
iatio
n or
oth
er
stan
dard
s or
gani
zatio
n (p
refe
r m
easu
ring
rim)
�R
im s
eat d
iam
eter
mus
t be
with
in to
lera
nces
fr
om s
tand
ards
(co
nfirm
ed w
ith b
all t
ape)
�P
ress
ure
tran
sduc
er o
r ga
uge
�T
wo
met
al v
alve
s or
“T
”va
lve
+ m
etal
val
ve
AS
TM
F11
12-0
6 In
flatio
n P
ress
ure
Loss
Rat
e (I
PLR
)
�T
est R
oom
•M
ean
tem
pera
ture
s of
21,
24,
30
or 3
8°C
(n
orm
al te
st is
21°
C)
±0.6
°C (
±1°F
)•
For
cibl
y ci
rcul
ated
air
cont
rolle
d at
±3°
C (
±5°F
)
�G
auge
s or
Pre
ssur
e T
rans
duce
rs
•R
esol
utio
n 2
kPa
(0.2
5 ps
i) ac
cura
te to
±1%
of
mea
sure
d va
lue
(ope
ratin
g w
ithin
40
to 9
0% o
f fu
ll sc
ale)
�D
ata
Acq
uisi
tion
•R
ecor
d da
ta o
nce
per
day
for
180
days
or
com
pute
r da
ta a
cqui
sitio
n of
mor
e da
ta p
oint
s pe
r da
y fo
r a
shor
ter
dura
tion
test
�B
arom
eter
(H
igh
Acc
urac
y)
AS
TM
F11
12-0
6 In
flatio
n P
ress
ure
Loss
Rat
e (I
PLR
)
�T
ires
are
infla
ted
to a
spe
cifie
d pr
essu
re a
nd s
it st
atic
an
d un
load
ed in
a c
ontr
olle
d en
viro
nmen
t•
NH
TS
A te
stin
g us
ed F
MV
SS
No.
139
Hig
h S
peed
test
pre
ssur
es
•N
HT
SA
test
ing
was
con
duct
ed a
t 21º
C ±
3ºC
�T
he p
ress
ure
and
cond
ition
s ar
e m
onito
red
over
tim
e•
NH
TS
A te
stin
g us
ed 9
0 da
ys w
ith c
ontin
uous
mon
itorin
g of
the
pres
sure
via
com
pute
r in
terf
ace
–P
er th
e st
anda
rd th
e fir
st 3
0 da
ys d
ata
was
dis
card
ed
�D
ata
is th
en c
orre
cted
to a
sta
ndar
d te
mpe
ratu
re a
nd
baro
met
ric p
ress
ure
•21
ºC a
nd 1
01.3
kP
a
Exa
mpl
e D
ata
Out
put
30 -
90 d
ay d
ata
is u
sed
to c
alcu
late
In
flatio
n P
ress
ure
Loss
Rat
e (I
PLR
)
Rat
e st
abili
zes
afte
r in
itial
30
days
:0
to 1
5 da
y =
3.30
%/m
onth
y =
-0.0
011x
+ 5
.406
3R
2 =
0.9
788
0 to
30
day
= 3
.0 %
/mon
thy
= -0
.001
x +
5.4
053
R2
= 0.
991 30
to 9
0 da
y =
2.40
%/m
onth
y =
-0.0
008x
+ 5
.401
R2
= 0.
9989
60 to
90
day
=2.4
0%/m
onth
y =
-0.0
008x
+ 5
.400
2
R2 =
0.9
972
5.30
5.32
5.34
5.36
5.38
5.40
5.42
5.44
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
Day
s
LnP
Is th
ere
a di
ffere
nce
in (
IPLR
) w
hen
vary
ing
N2/
O2
ratio
?
�O
ne-w
ay A
NO
VA
ana
lysi
s of
IPLR
:
Infla
tion
Gas
and
Tire
Typ
e ar
e S
igni
fican
t Var
iabl
es
Dep
ende
nt V
aria
ble:
IPLR
, Rat
e @
90
Day
s, %
/mon
thS
um o
f
Sou
rce
DF
Squ
ares
M
ean
Squ
are
F V
alue
P
r >
F
R-S
quar
eM
odel
2
7
56.4
1
2
.089
22.5
6
<.
0001
0.9
02E
rror
66
6
.11
0.
092
Cor
rect
ed T
otal
93
62.
52
Sou
rce
DF
T
ype
III S
S
Mea
n S
quar
eF
Val
ue
Pr
> F
Infla
tion
Gas
1
6
.842
6
.842
73.9
0
<.
0001
Tes
t Lab
1
0
.017
0
.017
0.19
0.
6668
Tire
Typ
e
25
4
0.53
1
.621
17.5
1
<.
0001
IPLR
with
Air
vs. N
2 In
flatio
n
17 D
iffer
ent
Mod
els
of
Tire
s
Ave
rage
IP
LR fo
r N
2w
as 6
6% o
f A
ir
IPLR
, In
flatio
n w
ith A
ir o
r N
2 g
as
0
0.51
1.52
2.53
3.54
4.5
B1
B7
B8
B9
C7
C8
D6
G1
M1
M3
N2
O4
P3
S1
T2
U2
Y2
Tir
e T
yp
e
IPLR, 90-day
0%
10
%
20
%
30
%
40
%
50
%
60
%
70
%
80
%
90
%
10
0%
IPLR N2 / IPLR Air
Air
N2
%
Tire
Par
amet
ers
�A
ppro
xim
ate
inne
rline
r va
riatio
ns:
•P
olym
er:
100%
IIR
�80
/20
NR
/SB
R•
Car
bon
blac
k: 5
3 �
76 p
hr
•N
on-b
lack
fille
r: 0
�22
phr
•T
otal
fille
r: 6
7 �
105
phr
•V
olat
iles:
13 �
26 p
hr
•T
hick
ness
0.6
7 �
1.85
mm
�In
itial
Infla
tion
Pre
ssur
e: 2
20
� ���52
1 kP
a
IPLR
Ver
sus
Tire
C
onst
ruct
ion
�O
f the
var
iabl
es s
tudi
ed, i
nner
liner
com
posi
tion
and
min
imum
thic
knes
s ha
d m
ost s
igni
fican
t ef
fect
on
IPLR
•F
iller
and
vol
atile
s ha
d si
gnifi
cant
, but
less
er e
ffect
s
�A
naly
sis
of d
iffer
ence
in IP
LRbe
twee
n ai
r an
d N
2 (I
PLR
air
–IP
LRni
trog
en)
by ti
re ty
pe•
No
sign
ifica
nt e
ffect
of a
ny c
onst
ruct
ion
para
met
er•
No
sign
ifica
nt e
ffect
of i
nitia
l inf
latio
n pr
essu
re–
Pas
seng
er /
LT ti
res
Ben
efits
of N
itrog
en In
flatio
n on
IPLR
A
ppea
r to
be
App
licab
le to
All
Tire
Typ
es
Nitr
ogen
Infla
tion
& O
xyge
n C
once
ntra
tion
Equ
ipm
ent
Bal
ston
®72
-730
O
xyge
n A
naly
zer
Acc
urat
e to
<0
.1%
O2
O2
Mig
ratio
n D
urin
g T
est
Change in
Perc
ent
Oxy
gen C
once
ntr
atio
n D
uring
IP
L T
est
Vers
us
Sta
rtin
g O
xygen C
once
ntr
atio
n
y =
-0
.00
16x
2 - 0
.05
19x
+ 0
.216
6R
2 = 0
.91
56
-7-6-5-4-3-2-101
02
46
81
012
141
61
82
02
22
426
283
03
23
43
63
840
424
44
64
85
052
% In
itial O
2
%O2 Loss During Test (90 days)
Cha
nge
in O
2Le
vels
�F
aste
r m
igra
tion
of O
2ch
ange
s m
ixtu
re o
f ga
s du
ring
90-d
ay te
st•
Tire
s in
flate
d w
ith a
ir lo
stav
erag
e of
1.5
% O
2
•T
ires
infla
ted
with
N2
lost
or
gain
ed O
2to
ap
proa
ch e
quili
briu
m p
artia
l pre
ssur
e
�O
2le
vels
wer
e m
easu
red
for
76 ti
res
that
w
ere
in-s
ervi
ce (
19 v
ehic
les)
in A
kron
, OH
•T
ires
wer
e or
igin
ally
infla
ted
with
sho
p ai
r at
va
rious
loca
tions
, no
spec
ial p
roce
dure
s
O2
Con
tent
Ver
sus
Infla
tion
Pre
ssur
eIn
-Ser
vice
Tire
s
79111315171921
1015
2025
3035
40
Infla
tion
Pre
ssur
e, p
si
% O2No
Cor
rela
tion
Bet
wee
n In
flatio
n P
ress
ure
and
% O
2
Dur
ing
serv
ice
with
top-
offs
of
norm
al a
ir, th
e ox
ygen
pe
rmea
tes
out
at a
fast
er r
ate
than
the
nitr
ogen
.
Thi
s ca
n re
sult
in a
>50
%
redu
ctio
n in
ne
t oxy
gen
leve
ls in
the
tire
infla
tion
gas
durin
g no
rmal
ser
vice
.
O2
Leve
l Sig
nific
antly
R
educ
ed In
-Ser
vice
Oxy
gen
Ran
ge
(% o
f in
flat
ion
gas)
N
umbe
r of
Tir
es
9 � ���
11
4 11
.1 � ���
13
18
13.1
� ��� 1
5 18
15
.1 � ���
17
17
17.1
� ��� 1
9 14
19
.1 � ���
20.
0 5
15.0
2 A
vera
ge
2.79
S
tan
dard
Dev
iati
on
Indi
cate
s R
educ
ed P
oten
tial B
enef
its
for
N2
Infla
tion
in N
orm
al T
ire S
ervi
ce
IPLR
Adv
anta
ge fo
r N
2In
Ser
vice
The
oret
ical
Dis
trib
utio
n of
IP
LR
Nor
mal
ized
to
Air
Rat
e =
100
for
Tir
e T
ype.
Nor
mal
ized
Dis
trib
utio
n of
:__
___
Air
wit
h 20
.9%
O2
____
_--
----
----
----
Nit
roge
n -
----
----
----
--__
-A
ir, D
eple
ted
of O
2 in
Ser
vice
__-
IPL
Rav
g=2.
1
IPL
Rav
g=1.
4IP
LR
avg=
1.8
Dyn
amic
Infla
tion
Pre
ssur
e Lo
ss –
Roa
dwhe
el T
estin
g
Infla
tion
Pre
ssur
e Lo
ss D
urin
g R
oadw
heel
T
estin
g W
as 3
7% L
ess
for
Tire
s In
flate
d w
ith N
2vs
. Tire
s In
flate
d w
ith A
ir
Cha
nge
in %
O2
Dur
ing
Dyn
amic
Loa
ded
Ope
ratio
n
Hig
her
%O
2G
as D
iffus
es M
ore
Rap
idly
D
urin
g D
ynam
ic R
oadw
heel
Tes
ting
Doe
s N
2H
ave
a D
irect
Effe
ct
on R
ollin
g R
esis
tanc
e?
�24
Tire
s w
ere
com
pare
d fo
r R
ollin
g R
esis
tanc
e, e
ither
in
flate
d w
ith N
2 or
Air
•S
AE
J12
69 S
ingl
e-P
oint
Tes
t�
Ave
rage
Rol
ling
Res
ista
nce
•A
ir =
12.
80 p
ound
s ±0
.38
•N
2=
12.
65 p
ound
s ±0
.44
�N
o D
irect
Effe
ct O
bser
ved
for
N2
Infla
tion
on T
ire
Rol
ling
Res
ista
nce
�T
he O
nly
Sig
nific
ant E
ffect
on
Tire
Rol
ling
Res
ista
nce
may
be
Indi
rect
: •
Due
to B
ette
r R
eten
tion
of In
flatio
n P
ress
ure
over
Tim
e
Effe
cts
on T
ire D
urab
ility
�T
he b
enef
its o
f N2
infla
tion
on o
ven-
aged
tir
es h
as b
een
show
n*
�T
he ti
res
wer
e fil
led
with
50
/50
N2/
O2,
air
or N
2an
d ov
en-a
ged
for
5 w
eeks
@
65ºC
�T
hey
wer
e th
en te
sted
ac
cord
ing
to th
e F
MV
SS
13
9 E
ndur
ance
and
Low
P
ress
ure
Tes
t (to
failu
re
or 3
5.5
hour
s st
op-f
inis
h)
�50
/50
N2/
O2
had
a si
gnifi
cant
del
eter
ious
ef
fect
. T
ires
aged
with
N2
or a
ir in
flatio
n al
l pas
sed
test
@ 3
5.5
hrs
*N
. Tok
ita, W
.D. S
igw
orth
, G.H
. Nyb
akka
n, G
.B. O
uyan
g, “
Long
-Ter
m D
urab
ility
of T
ires,
”P
aper
18
D17
, Pro
ceed
ings
of t
he In
tern
atio
nal R
ubbe
r C
onfe
renc
e, K
yoto
, 198
5, p
. 672
-679
.
J. M
. Bal
dwin
, D.R
. Bau
er, a
nd K
.R. E
llwoo
d, “
Effe
cts
of N
itrog
en In
flatio
n on
Tire
Agi
ng a
nd
Per
form
ance
,”P
aper
2, p
rese
nted
at R
ubbe
r D
ivis
ion,
AC
S, G
rand
Rap
ids,
MI,
May
17-
19, 2
004.
U. K
arm
akar
, “E
ffect
of N
itrog
en P
urity
on
the
Oxi
datio
n of
Bel
t Coa
t Com
poun
d,”
pres
ente
d at
th
e In
tern
atio
nal T
ire E
xpos
ition
and
Con
fere
nce,
Akr
on, O
H, S
epte
mbe
r, 2
006.
Con
clus
ion
(I)
�In
labo
rato
ry te
stin
g, ti
res
infla
ted
with
94-
99%
N
2sh
owed
a 3
4% r
educ
tion
in p
ress
ure
loss
ve
rsus
tire
s in
flate
d w
ith a
ir (7
8% N
2)•
Bas
ed o
n re
duce
d O
2ob
serv
ed fo
r in
-ser
vice
tire
s, th
e be
nefit
s of
N2
in s
ervi
ce w
ould
be
sign
ifica
ntly
red
uced
•T
ires
infla
ted
with
N2
abov
e 97
% p
urity
sho
wed
di
ffusi
on o
f O2
into
the
tire
at 9
0 da
ys�
Sim
ilar
redu
ctio
n in
IPLR
for
tires
infla
ted
with
N
2du
ring
800-
hour
dyn
amic
, loa
ded
road
whe
el
test
�In
nerli
ner
com
posi
tion
and
initi
al in
flatio
n pr
essu
re h
ad n
o si
gnifi
cant
effe
ct o
n re
duct
ion
of IP
LR fo
r N
2ve
rsus
air
Con
clus
ions
(I
I)
�T
ire in
flatio
n w
ith N
2ve
rsus
air
had
no
sign
ifica
nt e
ffect
on
rolli
ng r
esis
tanc
e•
Ben
efits
of N
2w
ill li
kely
be
indi
rect
from
impr
oved
re
tent
ion
of in
flatio
n pr
essu
re o
ver
time
�La
bora
tory
tire
end
uran
ce a
fter
oven
agi
ng w
as
redu
ced
by h
igh
O2
cont
ent i
n in
flatio
n ga
s du
ring
oven
agi
ng
•T
ires
infla
ted
with
air
or N
2du
ring
agin
g co
mpl
eted
the
post
-ove
n 35
.5 h
our
test
with
no
failu
res
•P
revi
ous
stud
ies
have
sho
wn
bene
fits
for
tire
road
whe
el
endu
ranc
e w
hen
tires
infla
ted
with
N2
durin
g ag
ing