Everything Rides on It

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tudiesoftiresafetyshowthatmaintainingpropertirepressure,observingtireandvehicleloadlimits

(notcarryingmoreweightinyourvehiclethanyourtiresorvehiclecansafelyhandle),avoidingroadhazards,andinspectingtiresforcuts,slashes,andotherirregularitiesarethemostimportantthingsyoucandotoavoidtirefailuresuchastreadseparation or blowout and flat tires. These actions alongwithothercareandmaintenanceactivitiescanalso:

Improvevehiclehandling;

Helpprotectyouandothersfromavoidablebreakdownsandcrashes;

Improvefueleconomy;and

Increasethelifeofyourtires.

This booklet presents a comprehensive overview oftiresafety,includinginformationonthefollowingtopics:

Basictiremaintenance;

Uniform Tire Quality Grading System;

Fundamentalcharacteristicsoftires;and

Tire safety tips.

Usethisinformationtomaketiresafetyaregularpartofyourvehiclemaintenanceroutine.Recognizethatthetimeyouspendisminimalcomparedwiththeinconvenienceandsafetyconsequences of a flat tire or other tire failure.

Safety First–Basic Tire Maintenance

Properlymaintainedtiresimprovethesteering,stopping,traction,andload-carryingcapabilityofyour vehicle. Underinflated tires and overloaded vehicles are a major cause of tire failure. Therefore, as mentioned above, to avoid flat tires and other

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typesoftirefailure,youshouldmaintainpropertirepressure,observetireandvehicleloadlimits,avoidroadhazards,andregularlyinspectyourtires.

Finding Your Vehicle’s Recommended Tire Pressure and Load Limits

Tire information placards and vehicle certification labelscontaininformationontiresandloadlimits.These labels indicate the vehicle manufacturer’s informationincluding:

Recommendedtiresize;

Recommended tire inflation pressure;

Vehiclecapacityweight(VCW–themaximumoccupantandcargoweightavehicleisdesignedtocarry);and

Frontandreargrossaxleweightratings(GAWR– the maximum weight the axle systemsaredesignedtocarry).

Both placards and certification labels are permanentlyattachedtothedriver’ssidevehicledoor edge or door post. You can also find the recommendedtirepressureandloadlimitforyourvehicleinthevehicleowner’smanual.

Understanding Tire Pressure and Load Limits

Tire inflation pressure is the amount of air in the tirethatprovidesitwithload-carryingcapacityandaffectstheoverallperformanceofthevehicle.The tire inflation pressure is a number that indicates theamountofairpressure—measuredinpoundspersquareinch(psi)—atirerequirestobeproperly inflated. (You will also find this number onthevehicleinformationplacardexpressedinkilopascals(kPa),whichisthemetricmeasureusedinternationally.)

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Manufacturersofpassengervehiclesandlighttrucksdeterminethisnumberbasedonthevehicle’sdesignloadlimit,thatis,thegreatestamountofweightavehiclecansafelycarryandthe vehicle’s tire size. The proper tire pressure for yourvehicleisreferredtoasthe“recommendedcold inflation pressure.” (As you will read below, it is difficult to obtain the recommended tire pressure ifyourtiresarenotcold.)

Becausetiresaredesignedtobeusedonmorethanonetypeofvehicle,tiremanufacturerslistthe“maximum permissible inflation pressure” on the tire sidewall. This number is the greatest amount ofairpressurethatshouldeverbeputinthetireundernormaldrivingconditions.

Remember, however, that the vehicle manufacturer, not the tire manufacturer, determines the correct tire pressure for

the tires on your vehicle.

Checking Tire Pressure

Itisimportanttocheckyourvehicle’stirepressureatleastonceamonthforthefollowingreasons:

Mosttiresnaturallyloseairovertime.

Tires can lose air suddenly if you drive over apotholeorotherobjectorifyoustrikethecurbwhenparking.

With radial tires, it is usually difficult to determine some levels of underinflation by visualinspection.

Forconvenience,buyatirepressuregaugetokeepinyourvehicle.Gauges can be purchased attiredealerships,autosupplystores,andotherretailoutlets.

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The recommended tire inflation pressure that vehicle manufacturers provide reflects the proper psi when a tire is cold. The term “cold” does not relatetotheoutsidetemperature.Rather,acoldtireisonethathasnotbeendrivenonforatleastthreehours.Whenyoudrive,yourtiresgetwarmer,causingtheairpressurewithinthemtoincrease. Therefore, to get an accurate tire pressure reading,youmustmeasuretirepressurewhenthetiresarecoldorcompensatefortheextrapressureinwarmtires.

Steps for Maintaining Proper Tire Pressure

Step �:Locatetherecommendedtirepressureonthe vehicle’s tire information placard, certification label,orintheowner’smanual.

Step 2:Recordthetirepressureofalltires.

Step 3:Ifthetirepressureistoohighinanyofthetires,slowlyreleaseairbygentlypressingonthetirevalvestemwiththeedgeofyourtiregaugeuntilyougettothecorrectpressure.

Step 4:Ifthetirepressureistoolow,notethedifferencebetweenthemeasuredtirepressureandthe correct tire pressure. These “missing” pounds ofpressurearewhatyouwillneedtoadd.

Step 5: At a service station, add the missing poundsofairpressuretoeachtirethatisunderinflated.

Step 6:Checkallthetirestomakesuretheyhavethesameairpressure(exceptincasesinwhichthefrontandreartireshavedifferentrecommendedinflation pressures).

Ifyouhavebeendrivingyourvehicleandthink that a tire is underinflated, fill it to the recommended cold inflation pressure indicated onyourvehicle’stireinformationplacardor

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certification label. While your tire may still be slightly underinflated due to the extra pounds ofpressureinthewarmtire,itissafertodrivewithairpressurethatisslightlylowerthanthevehiclemanufacturer’srecommendedcoldinflation pressure than to drive with a significantly underinflated tire. Since this is a temporary fix, don’t forget to recheck and adjust the tire’s pressurewhenyoucanobtainacoldreading.

Tire Size

To maintain tire safety, buy new tires that are the samesizeasthevehicle’soriginaltiresoranothersizerecommendedbythevehiclemanufacturer.Lookatthetireinformationplacard,theowner’smanual,orthesidewallofthetireyouarereplacingto find this information. If you have any doubt aboutthecorrectsizetochoose,consultwiththetiredealer.

Tire Tread

The tire tread provides the gripping action and tractionthatpreventyourvehiclefromslippingorsliding,especiallywhentheroadiswetoricy.Ingeneral,tiresarenotsafeandshouldbereplacedwhenthetreadisworndownto2/32ofaninch.

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Tires have built-in treadwear indicators that let you know when it is time to replace your tires. These indicatorsareraisedsectionsspacedintermittentlyinthebottomofthetreadgrooves.

When they appear “even” withtheoutsideofthetread,itistimetoreplaceyourtires.Another method for checking treaddepthistoplaceapennyinthetreadwithLincoln’sheadupsidedownandfacingyou.IfyoucanseethetopofLincoln’shead,youarereadyfornewtires.

Tire Balance and Wheel Alignment

To avoid vibration or shaking of the vehicle when atirerotates,thetiremustbeproperlybalanced.This balance is achieved by positioning weights onthewheeltocounterbalanceheavyspotsonthe wheel-and-tire assembly. A wheel alignment adjuststheanglesofthewheelssothattheyarepositionedcorrectlyrelativetothevehicle’sframe.This adjustment maximizes the life of your tires andpreventsyourcarfromveeringtotherightorleft when driving on a straight, level road. These adjustmentsrequirespecialequipmentandshouldbe performed by a qualified technician.

Tire Rotation

Rotatingtiresfromfronttobackandfromsidetosidecanreduceirregularwear(forvehiclesthathavetiresthatareallthesamesize).Lookinyourowner’smanualforinformationonhowfrequentlythetiresonyourvehicleshouldberotatedandthebestpatternforrotation.

Beawarethatsometiresmayhaveaone-directionaltreadpatternthatrequiresthemtobe

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operated in one direction only. Therefore, these tiresshouldonlyberotatedfromfronttobackonthesamesideofthevehicle.

A Tire Rotation Example

Tire Repair

The proper repair of a punctured tire requires a plug fortheholeandapatchfortheareainsidethetirethatsurroundsthepuncturehole.Puncturesthroughthetreadcanberepairediftheyarenottoolarge,butpuncturestothesidewallshouldnotberepaired.Tires must be removed from the rim to be properly inspectedbeforebeingpluggedandpatched.

Uniform Tire Quality Grading System

To help consumers compare a passenger car tire’streadwearrate,tractionperformance,andtemperatureresistance,theFederalgovernmentrequirestiremanufacturerstogradetiresinthesethree areas. This grading system, known as the Uniform Tire Quality Grading System, provides guidelinesformakingrelativecomparisonswhenbuyingnewtires.Youalsocanusethisinformationtoinquireaboutthequalityoftiresplacedonnewvehicles.

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Treadwear Grade

The treadwear grade is an indication of a tire’s relative wear rate. The higher the treadwear numberis,thelongeritshouldtakeforthetreadtoweardown.

Forexample,atiregraded400shouldlasttwiceaslongasatiregraded200.

Traction Performance Grade

The traction grade indicates a tire’s ability to stop on wet pavement. A higher graded tire should allowyoutostopyourcaronwetroadsinashorterdistance than a tire with a lower grade. Traction is graded from highest to lowest as AA, A, B, and C.

Temperature Resistance Grade

The temperature resistance grade indicates a tire’s resistance to heat. The temperature grade is for a tire that is inflated properly and not overloaded. Excessive speed, underinflation or excessive loading,eitherseparatelyorincombination,cancauseheatbuild-upandpossibletirefailure.Fromhighesttolowest,atire’sresistancetoheatis graded as A, B, or C.

Although this grading system is very helpful whenbuyingnewtires,itisnotasafetyratingorguaranteeofhowwellatirewillperformorhowlongitwilllast.Otherfactorssuchaspersonaldrivingstyle,typeofcar,qualityoftheroads,andtire maintenance habits have a significant influence onyourtire’sperformanceandlongevity.

Tire Fundamentals

Federallawrequirestiremanufacturerstoplacestandardizedinformationonthesidewallofalltires. This information identifies and describes thefundamentalcharacteristicsofthetireand

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also provides a tire identification number for safety standard certification and in case of a recall. Examplesofkeyinformationfoundonpassengervehicleandlighttrucktiresfollow.

Passenger Car Tires

TREADWEAR220TRACTION

ATE

MPERATUREA

RadialRatio of height towidth (aspect ratio)

Nominal width oftire in millimeters

Passengercar tire

Max.permissibleinflationpressure

Treadwear, tractionand temperature grades

Max. load rating

Tire plycompositionand materialsused

Severe snowconditions

U.S. DOT tireidentification number

Rim diametercode Load index &

speed rating

Sidewall Outer Circle

Passenger Car Tire The “P” indicates the tire is for passenger cars andotherlightvehicles.

Nominal Width This three-digit number gives the width in millimetersofthetirefromsidewalledgetosidewalledge.Ingeneral,thelargerthenumber,thewiderthetire.

Aspect RatioThis two-digit number, known as the aspect ratio,givesthetire’sratioofheighttowidth.Numbersof70orlowerindicateashortsidewallforimprovedsteeringresponseandbetteroverallhandlingondrypavement.

Radial The “R” stands for radial. Radial ply constructionoftireshasbeentheindustrystandardforthepast30years.

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Rim Diameter CodeThis two-digit number is the wheel or rim diameterininches.Ifyouchangeyourwheelsize,youwillhavetobuynewtirestomatchthenewwheeldiameter.

Load Index This two- or three-digit number is the tire’s loadindex.Itisameasurementofhowmuchweight each tire can support. You may find this informationinyourowner’smanual.Ifnot,contactalocaltiredealer.Note:Youmaynotfind this information on all tires because it is not requiredbylaw.

Speed Rating The speed rating denotes the maximum speed at which a tire is designed to be driven. The ratings range from 99 mph to 186 mph. These ratings arelistedbelow.Note: You may not find this informationonalltiresbecauseitisnotrequiredbylaw.

Q 99 mph H 130 mph

R 106 mph V 149 mph

S 112 mph W 168 mph*

T 118 mph Y 186 mph*

U 124 mph

*Fortireswithamaximumspeedcapabilityover149mph,tiremanufacturerssometimesusethelettersZR.Forthosewithamaximumspeedcapabilityover186mph,tiremanufacturersmustusethelettersZR.

Severe Snow Conditions The “M+S” or “M/S” indicates that thetirehassomemudandsnowcapability.Mostradialtireshavethesemarkings;hence,theyhavesomemudandsnowcapability.

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In some heavy snow areas, local governments may require true snow

tires, those with very deeply cut tread. These tires should only be used in pairs or placed on all four wheels. Make sure you buy snow tires that are the same size as the other tires

on your vehicle.

Sidewall Inner Circle

U.S. DOT Tire Identification Number This begins with the letters “DOT” and indicates that the tire meets all Federal standards. The next twonumbersorlettersaretheplantcodewhereitwasmanufactured,andthelastfourdigitsrepresenttheweekandyearthetirewasbuilt.Forexample,thedigits3197meansthe31stweek of 1997. The other numbers are marketing codes used at the manufacturer’s discretion. This informationisusedtocontactconsumersifatiredefectrequiresarecall.

Tire Ply Composition and Materials UsedThe number of plies indicates the number of layersofrubber-coatedfabricinthetire.Ingeneral,thegreaterthenumberofplies,themoreweight a tire can support. Tire manufacturers alsomustindicatethematerialsinthetire,whichincludesteel,nylon,polyester,andothers.

Maximum Load RatingThis number indicates the maximum load in kilogramsandpoundsthatcanbecarriedbythetire.

Maximum Permissible Inflation PressureThis number is the greatest amount of air pressurethatshouldeverbeputinthetireundernormaldrivingconditions.

Light-Truck Tires Tires for light trucks have other markings besides thosefoundonthesidewallsofpassengertires.

LT

235/

85R16 D 114/111Q

MAX. LOAD DUAL 1883 AB (2281 lbs) • AT 455 kPa (55 psi) COLD • LOAD RANGED • MAX. LOAD SIN

GLE

1110

xg

(262

3 lb

s) •

AT 4

55 kP

a (55 psi) COLD •

Loadrange

Lighttruck tire

Maximum load& inflation whenused as a single

Maximum load& inflation whenused as a dual

Severe snow conditionsSee page 9

Light Truck TireThe “LT” indicates the tire is for light trucks.

Load RangeThis information identifies the tire’s load-carrying capabilities and its inflation limits.

Maximum Load DualThis information indicates the maximum load andtirepressurewhenthetireisusedasadual,thatis,whenfourtiresareputoneachrearaxle(atotalofsixormoretiresonthevehicle).*

Maximum Load SingleThis information indicates the maximum load andtirepressurewhenthetireisusedasasingle.*

*Maximumloadispresentedinkilogramsandpounds(kg/lbs).Maximumtirepressureispresentedinkilopascalsandpoundspersquareinch(kPa/psi)forwhenthetireiscold.

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Tire Safety Tips

Preventing Tire Damage

Slowdownifyouhavetogooverapotholeorotherobjectintheroad.

Donotrunovercurbsorforeignobjectsintheroadway,andtrynottostrikethecurbwhenparking.

Tire Safety Checklist

✔ Checktirepressureregularly(atleastonceamonth),includingthespare.

✔ Inspecttiresforcracks,foreignobjects,unevenwearpatternsonthetread,orothersignsofwearortrauma.

✔ Removebitsofglassandotherforeignobjectswedgedinthetread.

✔ Makesureyourtirevalveshavevalvecaps.

✔ Checktirepressurebeforegoingonalongtrip.

✔ Donotoverloadyourvehicle.Checkthetireinformationplacardorowner’smanualforthemaximumrecommendedloadforthevehicle.

✔ Ifyouaretowingatrailer,rememberthatsomeoftheweightoftheloadedtraileristransferredtothetowingvehicle.

For more information, visit www.nhtsa.gov or call 888-327-4236

DOT HS 810 900