56 7August2019 http://www.autoexpress.co.uk
GETTINGAGRIPON
TYREPERFORMANCE
THEopenspacesoftheUvaldeproving
groundinTexas,USA,areperfectfor
puttingatyrethroughitspaces.Ourwetand
drytestsweredonethere,pluscabinnoise,
usingvarioussurfacesontheovaltrack.
RollingresistancewascheckedinGermany
atContinental’sR&DcentreinHanover,and
wesourcedUKprices.Allprovingground
evaluationwasdonebyAutoExpresstesters,
apartfromaquaplaning,whichrequires
specialistskillsandexperience.Thiswas
donebyprovinggroundstaff.
Thewaywefoundawinnerwasrefinedthis
year.Aswehavedonepreviously,theresults
wereconvertedtopercentagestoaccurately
reflecttheperformancedifferencesbetween
tyres.Thesewereaddedtogethertoformthe
finalresult.Weonlyweightedteststoensureallcontributedthesametothefinalresult,with
thewettestsaccountingforhalftheresultand
therestsplitbetweentheotherassessments.
Thistime,ratherthanjustlookingatthe
spreadofindividualresults,wefactoredin
howmucheachcontributedtothetestresult.
Wherewehadtomakeachoicewefavoured
keyfactors,likehandlingandbraking.Price
playsasmallpartintheoverallresult.THEconditionswheremostdriverswillget
closetooroverstepthelimitareinthewet,so
thesetestsarekeytoanytyre’sperformance.
It’snosurprisethatit’spartoftheEUlabelling
system,butinsteadoflookingatjustbraking
wealsotesthandling,lateralgripandhow
thetyreresistsaquaplaningindeepwater.
Thehandlingwasdoneatthe1.1-miletrack
thatsnakesacrosstheTexanscrub.Itmimics
thecircuitatContinental’sGermancentre
rightdowntotonsoftarmacimportedina
seriesofcontainerstoreplicatethesurface.
Theresultisbasedonanaverageof
severallaptimes.Beforeheadingtothe
track,wecompletedupto10lapsofthe
55-metrewetcircle,whichmeasurespure
lateralgrip.Again,theresultisbasedon
anaverageoflaptimes.Bothtestsanddry
handlingweredoneinaprevious-generation
VolkswagenTiguan–amodelthathad
ourtesttyreasoriginalequipment.
Brakingwasdoneusingtherailsystem,
whichensuresthatpreciselythesamepiece
oftrackisusedeach timetoassistgetting
consistentresults.We didaseriesofstops
andmeasuredthedistancetakentohalt
from50mph.Theresultwasbasedon
multiplestopswithoutliersremoved.
Thewaterdepthonallthesetestswas
aroundamillimetre,buttoseehowthetyre
copedwithdeeperflooding,wemeasured
bothlateralandlongitudinalaquaplaning.
Thecurvedtestwasdonein6mm-deep
waterandthestraightin8mm.Forthe
formerthecarwasdrivenatsetspeed
increasesthroughasoakedsectionofa
tarmaccircle.Thelossoflateralgripwas
measuredasthespeedwentup,andthe
tyrescomparedusingindustrystandards.
Forthestraighttest,therailwasused
andthecarwasacceleratedwithonewheel
inwater.Thedifferencebetweenthetwo
wasmeasured,withthespeedwhentheslip
exceeds15percentrecorded–thepointat
whichcontrolislost.Anaverageofmultiple
runswasusedtogetthefinalcomparison.AT theUvaldeprovinggroundthere
isarelativelynewdryhandlingcircuit,
whichweusedlastyear.Thistimewe
didourtestsona2,000-metresection,
removingtheultra-fastfinalportion
whichrevealedlittleaboutthetyre.
Thetestsectionprovidedtwolong
sweeps,whichreallyallowedthetyre
tobeassessed,plustightturns,a
bankedcornerandrapiddirection
changes.Ourtestresultwasbased
onanaverageoflaptimes.
Drybrakingwasdoneonthethree-mile
ovaltrack,withthedistancemeasured
from62mphtoastop.Anaverageof
severalrunswasusedforthefinalresult.THEEUtyre-labellingsystemmeasures
pass-bynoisebecauseitfocuseson
environmentalconcerns.Butformany
driversthekeyfactoriscabinnoise,
whichiswhyitispartofourtest.
We coasteddownfrom50mphover
threesurfaces–smoothandrough
tarmac,plusconcrete–measuring
noiselevels.Anaverageofthethree
surfacesformsthetestresult.TYRE TEST 2019
OurtestershavebeenbusybothontrackintheUSAandatanR&DcentreinGermany
rigorouslyputtingarangeoftyresthroughtheirpacesforourtest.Here’swhatwedid
HOWWETESTED
WETTESTING
CABINNOISE
DRYTESTING
SIGN OF THE TIMESOur testerschecked
each tyre’s performanceinthe dry, as
well as in the wet,using aVWTiguanPictures:NathanMorgan