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T o m aintain g o o d h a n dlin g a n d v e hicl e
re s p o ns e, u s e o nly tire s of a sin gle
tre a d c o nfig ura tio n fro m a sin gle m a n u -
fa cturer. B M W t e sts a n d a p prov e s
w h e el/tir e c o m bin a tio ns, b e ginnin g on
p a g e 1 3 7 .
D OT Q uality Grades
Tre a d w e ar
Tra ctio n A A A B C
T e m p era ture A B C
All p ass e n g er v e hicl e tire s m u st
c o nform to F e d eral S af ety
R e quire m e nts in a d ditio n to th e s e
gra d es. <
Tread wear
Th e tre a d w e ar gra d e is a c o m p arativ e
ratin g b as e d o n th e w e ar ra t e of th e tire
w h e n te st e d u n d er c o ntrolle d c o n di-
tio n s o n a s p e cifie d g o v ern m e nt t e st
c o urs e .
F or e x a m p l e , a tire gra d e d 1 50 w ould
w e ar o n e a n d on e - h alf (1g) tim e s a s
w ell o n th e g o v ern m e nt c o urs e a s a tir e
gra d e d 10 0. T h e relativ e p e rform a n c e
of tire s d e p e n d s u p on th e a ctu al c o n di-
tio n s of th eir us e , ho w e v er, a n d m a y
d e p art sig nific antly fro m th e n orm d u e
to v ariatio ns in drivin g h a bits, s ervic e
pra ctic es a n d diff ere n c es in ro a d c h ar-
a cteristic s a n d clim ate .
Traction
Th e tra ctio n gra d e s, fro m hig h e st to
lo w e st, are A A , A , B , a n d C .
Th os e gra d e s re pre s e nt th e tire's a bility
to sto p o n w e t p a v e m e nt a s m e asure d
un d er c o ntrolle d c o n ditio ns o n s p e ci-
fie d g o v ern m e nt t e st s urf a c e s of
as p h alt a n d c o n crete . A tir e m ark e d C
m a y h a v e p o or tra ctio n p erform a n c e .
Th e tra ctio n gra d e a ssig n e d to
this tire is b a s e d o n straig ht-
a h e a d bra kin g tra ctio n te sts, a n d d o e s
not in clu d e a c c e l e ratio n, c orn erin g ,
hydro pla nin g, or p e a k tra ctio n
c h ara ct e ristic s. <
Temperature
Th e te m p erature gra d e s are A (th e
hig h e st), B , a n d C , re pre s e ntin g th e
tire's r e sista n c e to th e g e n eratio n of
h e at a n d its a bility to d is si p a t e h e at
w h e n te st e d u n d er c o ntrolle d c o n di-
tio n s o n a s p e cifie d in d oor la b oratory
te st w h e el.
S u stain e d high t e m p era ture c a n c a u s e
th e m a t erial of th e tire to d e g e n e rate
a n d re d u c e tire lif e , a n d e x c e ssiv e
te m p era ture c a n le a d to su d d e n tir e
failure. T h e gra d e C c orre s p on d s to a
le v el of p erf orm a n c e w hic h all
p a s s e n g er v e hicl e tire s m ust m e et
un d er th e F e d eral M otor V e hicl e S af ety
Sta n d ard N o. 1 09. G ra d es B a n d A
re pr e s e nt hig h er le v els of p erf orm a n c e
on th e la b oratory te st w h e el th a n th e
minim u m re q uire d b y la w .
Th e te m p era ture gra d e for this tire
is e sta blis h e d f or a tire th at is
pro p e rly inflate d a n d not o v e rlo a d e d .
E xc e ssiv e s p e e d, u n d erinflatio n, or
e x c e ssiv e lo a d in g, eith er s e p arat e ly or
in c o m bin atio n, c an c a us e h e a t b uild u p
a n d p o ssible tire failure. <
Uniform Tire Quality Grading
Q u ality gra d e s c a n b e f o u n d w h ere
a p pli c a bl e o n th e tire si d e w all b etw e e n
tre a d sh o ul d er a n d m a xim u m s e ctio n
width. F or e xa m pl e :
Tre a d w e ar 2 0 0 Tra ctio n A A
T e m p era ture A
D o n ot u s e re tre a d e d tire s. Drivin g
saf ety m a y b e im p aire d b y th e ir
us e. T his is d u e to th e p o s si ble v aria -
tio n s in c a sin g stru cture s a n d , in s o m e
c a s e s, to th eir e xtr e m e a g e , f a ctors th at
c a n le a d to a d e cr e as e in th eir
d ura bility. <
Tire replacement
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