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ROLLINGROLLINGROLLINGROLLING RESISTANCERESISTANCERESISTANCERESISTANCE OOOOFFFF TIRESTIRESTIRESTIRES FORFORFORFOR
LIGHTLIGHTLIGHTLIGHT VEHICLESVEHICLESVEHICLESVEHICLES IIIII:I:I:I: COMPARISONCOMPARISONCOMPARISONCOMPARISON OFOFOFOF
ROLLINGROLLINGROLLINGROLLING RESISTANCERESISTANCERESISTANCERESISTANCE VALUESVALUESVALUESVALUES OBTAINEDOBTAINEDOBTAINEDOBTAINED
FROMFROMFROMFROM DIFFERENTDIFFERENTDIFFERENTDIFFERENT TESTTESTTESTTEST METHODSMETHODSMETHODSMETHODS ANDANDANDAND ININININ
DIFFERENTDIFFERENTDIFFERENTDIFFERENT LABORATORIESLABORATORIESLABORATORIESLABORATORIES
AAAAUTHORUTHORUTHORUTHOR:::: LLLLARRY ARRY ARRY ARRY EEEEVANSVANSVANSVANS
TTTTRANSPORTARANSPORTARANSPORTARANSPORTATION TION TION TION RRRRESEARCH ESEARCH ESEARCH ESEARCH IIIINSTITUTENSTITUTENSTITUTENSTITUTE
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JJJJOHN OHN OHN OHN HHHHARRISARRISARRISARRIS
TTTTRANSPORTATION RANSPORTATION RANSPORTATION RANSPORTATION RRRRESEARCH ESEARCH ESEARCH ESEARCH IIIINSTITUTENSTITUTENSTITUTENSTITUTE
JJJJAMES AMES AMES AMES MMMMACACACACIIIISAACSAACSAACSAAC
DOTDOTDOTDOT –––– NHTSANHTSANHTSANHTSA
EEEED D D D TTTTERRILLERRILLERRILLERRILL,,,, PPPPHHHH.D..D..D..D.
AAAAKRON KRON KRON KRON RRRRUBBER UBBER UBBER UBBER DDDDEVELOPMENT EVELOPMENT EVELOPMENT EVELOPMENT LLLLABORATORYABORATORYABORATORYABORATORY,,,, IIIINCNCNCNC....
ITECITECITECITEC 2008200820082008
PPPPAPER APER APER APER 11118C8C8C8C----3333
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Rol
ling
Res
ista
nce
of T
ires
for
Ligh
t V
ehic
les,
II:
Com
paris
on o
f Rol
ling
Res
ista
nce
Val
ues
Obt
aine
d fr
om D
iffer
ent T
est
Met
hods
and
in D
iffer
ent L
abor
ator
ies
Larr
y E
vans
& J
ohn
Har
ris, T
rans
port
atio
n R
esea
rch
Cen
ter,
Inc.
Jam
es D
. Mac
Isaa
c Jr
., U
SD
OT
-N
HT
SA
Pre
sent
ed a
t IT
EC
200
8A
kron
, OH
Sep
tem
ber
17, 2
008
Obj
ectiv
e
�S
elec
t a M
etho
d to
Mea
sure
Tire
Rol
ling
Res
ista
nce
in O
rder
to C
ompa
re T
ires
•S
AE
J24
52 v
alue
s at
var
ious
spe
ed, l
oad,
and
in
flatio
ns u
sed
to r
elat
e tir
e pr
oper
ties
to v
ehic
le–
SM
ER
F (
Sta
ndar
d M
ean
Equ
ival
ent R
ollin
g F
orce
)
•S
AE
J12
69 a
nd IS
O 1
8164
des
crib
e th
e tir
e re
spon
se a
t var
ious
load
and
infla
tion
cond
ition
s–
SR
C (
Sta
ndar
d R
efer
ence
Con
ditio
n)
•S
AE
J12
69 a
nd IS
O 2
8580
test
a ti
re a
t st
anda
rd c
ondi
tions
of s
peed
, loa
d, a
nd in
flatio
n
Mea
surin
g R
ollin
g R
esis
tanc
e
�E
valu
ate
Sou
rces
of V
aria
bilit
y in
Tes
ting
•T
ire –D
iffer
ent T
ire T
ypes
–D
iffer
ent T
ires
of S
ame
Typ
e–
Sam
e T
ire –
Rep
eat T
estin
g
•La
b•
Tes
t
Tes
t Mat
rix
�F
ive
Tes
t Pro
toco
ls�
25 T
ire T
ypes
�2
Labs
�C
appe
d or
Reg
ulat
ed P
ress
ure
(J12
69)
�F
irst,
Sec
ond
and
Thi
rd T
ests
on
Indi
vidu
al
Tire
s�
Diff
eren
t Inf
latio
n G
as�
641
Tes
ts�
Onl
y on
e tir
e w
as a
n ou
tlier
from
oth
er ti
res
of
the
sam
e m
odel
AN
OV
A
�A
naly
sis
of V
aria
nce
was
con
duct
ed o
n re
sults
fr
om e
ach
test
•S
AE
J12
69 S
ingl
e-P
oint
•S
AE
J12
69 M
ulti-
Poi
nt
–C
alcu
late
d va
lue
at S
RC
usi
ng r
egre
ssio
n sp
ecifi
ed
•IS
O D
IS28
580
Sin
gle-
Poi
nt•
ISO
181
64 M
ulti-
Poi
nt–
Cal
cula
ted
at S
RC
usi
ng J
1269
reg
ress
ion
met
hod
•S
AE
J24
52–
SM
ER
F–
Cal
cula
ted
valu
e at
SR
C u
sing
J24
52 r
egre
ssio
n
SA
E J
1269
Sin
gle-
Poi
nt
Dep
ende
nt V
aria
ble:
Rol
ling
Res
ista
nce
Sum
of
Mea
nS
ourc
e
DF
S
quar
es
S
quar
e
F V
alue
P
r >
FM
odel
29
49
358.
7
170
2.0
15
122.
2<.
0001
Err
or
19
1
2
1.5
0.11
Unc
orre
cted
Tot
al
22
0
49
380.
2
R-S
quar
e
Coe
ffV
arR
oot M
SE
RR
Mea
n0.
9959
852.
3715
65
0.
3354
87
1
4.14
623
Sou
rce
D
F
Typ
e III
SS
Mea
n S
quar
e
F V
alue
P
r >
FLa
b W
here
Tes
ted
1
9
.45
9.
4583
.99
<.
0001
Pro
cedu
re fo
r In
flatio
n
1
2.99
2.
9926
.62
<.
0001
Tes
t Ord
er
2
0
.07
0.
036
0.
32
0.7
265
Typ
e (T
ire M
odel
)
24
4
871.
64
20
2.9
8
180
3.49
<
.000
1
AN
OV
A C
ompa
rison
1,69
9.70
89.9
485
3.61
4,57
4.38
1,80
3.49
F V
alue
–T
ire M
odel
26.5
74.
30*
0.68
0.23
0.32
F V
alue
–T
est O
rder
NA
NA
NA
NA
26.6
2F
Val
ue -
Cap
ped
/ R
egul
ated
544.
344.
30*
2.14
11.2
483
.99
F V
alue
-La
b
0.99
530.
9891
0.99
670.
9960
0.99
60R
2
23,5
352,
687.
68,
320.
915
,929
.515
,122
.2F
Val
ue
J245
2 S
ME
RF
ISO
181
64(1
0 T
ires)
ISO
D
IS28
580
J126
9 M
ulti-
Poi
ntJ1
269
Sin
gle-
Poi
nt
Tes
t
* V
aria
ble
s w
ere c
on
fou
nd
ed
AN
OV
A C
oncl
usio
ns
�F
and
R2
valu
es in
dica
te th
at th
e so
urce
s of
var
iatio
n ar
e ac
coun
ted
for
in m
odel
•T
ire ty
pe is
the
mos
t sig
nific
ant v
aria
ble
•T
he tw
o la
bs s
tudi
ed p
rodu
ced
sign
ifica
ntly
di
ffere
nt v
alue
s•
Cap
ped
vs. r
egul
ated
infla
tion
pres
sure
dur
ing
the
test
was
sig
nific
ant
•F
irst,
seco
nd, o
r th
ird te
st o
n th
e sa
me
tire
was
no
t a s
igni
fican
t var
iabl
e
Lab
Var
iatio
n
�T
est o
rder
(1
st, 2
nd, 3
rd)
igno
red
�C
oeffi
cien
t of V
aria
tion
with
in a
lab
for
a tir
e ty
pe o
n a
test
was
≤
2.5%
•V
alue
s w
ere
norm
ally
dis
trib
uted
with
in e
ach
lab
�T
here
was
a s
igni
fican
t var
iatio
n be
twee
n la
bs fo
r al
l tes
ts
Lab
Offs
et
J126
9 S
ingl
e-P
oint
Tes
t
Rol
ling
Res
ista
nce
@ L
ab B
= 0
.257
+ 1
.024
*(L
ab A
)
Lab
Offs
et
0.99
15B
= -
0.14
3 +
1.07
7*A
J245
2S
ME
RF
0.96
23B
= 0
.714
+ 0
.908
*AIS
O 1
8164
0.96
23B
= -
0.09
9 +
1.01
2*A
ISO
285
80
Sin
gle-
Poi
nt
0.96
59B
= -
1.74
6 +
1.01
2*A
J126
9 M
ulti-
Poi
nt
0.99
75B
= 0
.257
+1.0
24*A
J126
9 S
ingl
e-P
oint
R2
Cor
rela
tion
of L
ab B
to L
ab A
Tes
t
Lab
to L
ab C
orre
latio
n
�S
tatis
tical
ly s
igni
fican
t offs
et b
etw
een
labs
.•
Lab
B h
ad h
ighe
r va
lues
than
Lab
A fo
r 3
of th
e te
sts
•La
b B
had
low
er v
alue
s th
an L
ab A
for
1 te
st
•E
qual
on
aver
age
for
1 te
st
�A
slig
htly
bet
ter
pred
ictio
n of
lab
offs
et
coul
d be
obt
aine
d w
ith a
non
-line
ar
equa
tion,
esp
ecia
lly fo
r m
ulti-
poin
t tes
ts
Lab-
to-L
ab O
ffset
Cor
rela
tion
of
Lab
B t
o L
ab A
fo
r al
l con
diti
ons
of t
he J
1269
M
ulti
-Poi
nt t
est.
T
est
Poi
nt 1
[C
ap
ped
In
flatio
n]is
sig
nifi
cant
ly
offs
et
Var
iabi
lity
of T
est
1.9%
J245
2 S
ME
RF
5.2%
ISO
181
64 (
10 T
ires)
2.2%
ISO
DIS
2858
0
2.4%
J126
9 M
ulti-
Poi
nt
2.4%
J126
9 S
ingl
e-P
oint
Coe
ffici
ent o
f Var
iatio
nT
est
Mea
surin
g R
ollin
g R
esis
tanc
e
�S
ourc
es o
f Var
iabi
lity
in T
estin
g•
Diff
eren
t Tire
s of
Sam
e T
ype
–O
nly
1 T
ire s
igni
fican
tly d
iffer
ent
•S
ame
Tire
–R
epea
t Tes
ting
–N
o si
gnifi
cant
effe
ct
•La
b–
Sig
nific
ant d
iffer
ence
s�
Var
ies
by te
st a
nd c
ondi
tions
•T
est
–A
ll te
sts
have
low
Coe
ffici
ent o
f Var
iatio
n (C
.V.)
Ran
king
Tire
Rol
ling
Res
ista
nce
�D
ata
for
valu
es fr
om L
ab A
cor
rect
ed to
La
b B
val
ues
usin
g co
rrel
atio
n eq
uatio
ns�
Do
test
s ra
nk-o
rder
tire
s di
ffere
ntly
?�
Rol
ling
resi
stan
ce o
f tire
s w
as g
roup
ed
usin
g le
ast s
igni
fican
t diff
eren
ces
at 9
5%
conf
iden
ce le
vel f
or d
ata
from
eac
h te
st
Cor
rela
tion
of T
est D
ata
5T =
SA
E J
2452
SM
ER
F
valu
e, L
ight
Tru
ck T
ires
5P
= S
AE
J2
452
SM
ER
F
valu
e, P
asse
nger
Tire
s
4T =
SA
E J
2452
val
ue @
S
RC
, Lig
ht T
ruck
Tire
s
4P =
SA
E J
2452
val
ue @
S
RC
, Pas
seng
er T
ires
3 =
ISO
18
164
valu
e @
S
RC
2 =
SA
E J
1269
mul
ti-po
int
valu
e @
SR
C
1 =
ISO
285
80 s
ingl
e-po
int v
alue
Pas
seng
er T
ire G
roup
s
R4
B12
B13
R4
B12
B13
B13
B12
R4
B13
B12
B12 R4
B13
R4
B13
B12
4(H
ighest
)
D10 U3
B14 P5
B15
D10 U3
B14 P5
B15
U3
B14
D10
B14 U3
B15 P5
U3
D10 P5
B14
B15
D10 U3
P5
B14
B15
3
G9
M13
G10
M14
B10
G9
M13
G10
M14
B10
G9
M14
G10
G9
M13
M14
G10
B10
G9
G10
M14
M13
B10
G9
G10
M13
M14
B10
2
G11 G8
B11
G11
B11 G8
G11 G8
B11
G8
B11
G11
G11
B11 G8
B11 G8
G11
1 (L
ow
est
)
J245
2,
SME
RF
J245
2 @
SR
CIS
O 1
8164
ISO
285
80J1
269
mul
ti-
poin
t@
SRC
J126
9 Si
ngle
-P
oint
Gro
up
Ligh
t Tru
ck T
ire G
roup
s
C9
C9
C9
C9
C9
6(H
ighest
)
D9
D9
D9
D9
D9
5
M12
M10
M11
K4
P4
D8
D7
M12
M10
M11
K4
P4
D8
D7
M10
M
12
M11
K4
P4
D8
D7
M10
M12
K4
M11
D8
P4
D7
M10
M12
M11
D8
K4
D7
P4
4 (L
ow
est
)
J245
2, S
ME
RF
J245
2 @
SR
CIS
O 2
8580
J126
9 m
ulti
-po
int@
SR
CJ1
269
Sing
le-
Poi
nt
Gro
up
Sel
ectio
n of
Met
hod
�A
ll m
etho
ds p
rodu
ce d
ata
with
low
var
iatio
n�
All
met
hods
ran
k tir
es in
to th
e sa
me
grou
ps�
Dat
a fr
om a
ny m
etho
d ca
n be
cor
rela
ted
to d
ata
from
any
oth
er m
etho
d�
Sin
gle-
poin
t met
hod
is m
ost e
ffici
ent
�A
ny m
etho
d se
lect
ed w
ill n
eed
a pr
oced
ure
to
acco
unt f
or la
b-to
-lab
diffe
renc
es
Ran
king
Tire
s U
sing
RR
C
�R
ollin
g R
esis
tanc
e C
oeffi
cien
t (R
RC
) is
of
ten
used
to r
epor
t the
rol
ling
resi
stan
ce
of ti
res
•R
RC
is R
ollin
g R
esis
tanc
e F
orce
/ N
orm
al F
orce
–U
sing
sam
e un
its r
emov
es th
e di
men
sion
�W
hen
com
parin
g tir
es te
sted
at t
he s
ame
load
, the
re is
no
chan
ge in
com
paris
ons
�C
an R
RC
be
used
to c
ompa
re ti
res
of
diffe
rent
load
rat
ings
?
Cor
rela
tion
of T
est D
ata
5T =
SA
E J
2452
SM
ER
F
valu
e, L
ight
Tru
ck T
ires
5P
= S
AE
J2
452
SM
ER
F
valu
e, P
asse
nger
Tire
s
4T =
SA
E J
2452
val
ue @
S
RC
, Lig
ht T
ruck
Tire
s
4P =
SA
E J
2452
val
ue @
S
RC
, Pas
seng
er T
ires
3 =
ISO
18
164
valu
e @
S
RC
2 =
SA
E J
1269
mul
ti-po
int
valu
e @
SR
C
1 =
ISO
285
80 s
ingl
e-po
int v
alue
RR
C C
alcu
latio
n
�W
hile
RR
C is
dim
ensi
onle
ss, i
t is
not
inde
pend
ent o
f con
ditio
ns o
f tes
ting
�F
or p
asse
nger
tire
s us
ing
J126
9 R
R:
RR
_For
ce=
Loa
d*(A
1+
A2*
Load
+ A
3÷P
ress
ure)
–D
ivid
ing
both
sid
es b
y lo
ad
RR
C =
A1
+ A
2*Lo
ad +
A3÷
Pre
ssur
e–
At c
onst
ant p
ress
ure
RR
C =
A2*
Load
+ A
1 +
A3÷
k
RR
C is
stil
l a fu
nctio
n of
load
J245
2 an
d LT
tire
s ar
e ev
en m
ore
com
plex
RR
C V
s. L
oad
–T
ire T
ype
D7
RR
C: T
ire D
7 (L
T)
0.00
8
0.00
9
0.01
0.01
1
0.01
2
0.01
3
0.01
4
0.01
5
0.01
6
0.01
7 1000
1500
2000
2500
3000
Load
, Pou
nds
RR Index, [Mich LTX=100]
Ran
ge o
f Ave
rage
Val
ues
for A
ll Tire
s
RR
C is
be
twee
n 0.
0093
and
0.
0161
, de
pend
ing
on
test
con
diti
on.
It is
not
an
intr
insi
c pr
oper
ty o
f th
e ti
re
Con
clus
ions
(I)
�U
p to
3 r
epea
t tes
ts o
f the
sam
e tir
e ha
s no
si
gnifi
cant
effe
ct o
n ro
lling
res
ista
nce
valu
es�
As
expe
cted
, tes
ting
with
cap
ped
infla
tion
pres
sure
pro
duce
s a
low
er v
alue
, due
to
incr
ease
d pr
essu
re�
Tire
s of
the
sam
e m
odel
and
siz
e pr
oduc
e eq
uiva
lent
rol
ling
resi
stan
ce v
alue
s, ±
~6%
•D
ata
is n
orm
ally
dis
trib
uted
•
1 ou
tlier
tire
dis
cove
red
Con
clus
ions
(II)
�La
b-to
-Lab
var
iatio
n is
sig
nific
ant
•D
epen
dent
on
test
con
ditio
ns a
nd p
roto
col
�A
ll te
sts
prod
uce
relia
ble
data
with
low
va
riatio
n�
All
test
s ra
nk o
rder
tire
s in
to th
e sa
me
grou
ping
s�
Val
ues
for
all t
ests
are
app
roxi
mat
ely
linea
r fu
nctio
ns o
f the
val
ues
of a
ny o
ther
test
�R
ollin
g R
esis
tanc
e or
RR
Coe
ffici
ent d
escr
ibe
a tir
e’s
resp
onse
at t
he c
ondi
tions
of t
est o
nly
