Properly torqued wheel nuts are necessary to helpprevent brake pulsation. When tires are rotated, inspectbrake pads for wear and evenly tighten wheel nuts inthe proper sequence to torque specifications inCapacities and Specifications on page 6-109.
Brake linings should always be replaced as completeaxle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does notreturn to normal height, or if there is a rapid increase inpedal travel. This could be a sign that brake servicemight be required.
Brake Adjustment
Every time the brakes are applied, with or without thevehicle moving, the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its manyparts have to be of top quality and work well together ifthe vehicle is to have really good braking. The vehiclewas designed and tested with top-quality brake parts.When parts of the braking system are replaced — forexample, when the brake linings wear down and newones are installed — be sure to get new approvedreplacement parts. If this is not done, the brakes mightnot work properly.
For example, if someone puts in brake linings that arewrong for the vehicle, the balance between the front andrear brakes can change — for the worse. The brakingperformance expected can change in many other ways ifthe wrong replacement brake parts are installed.
Battery
Refer to the replacement number on the original batterylabel when a new battery is needed.
{DANGER:
Battery posts, terminals, and related accessories
contain lead and lead compounds, chemicals
known to the State of California to cause cancer
and reproductive harm. Wash hands after
handling.
The battery is under the rear seat cushion. To accessthe battery, seeRear Underseat Fuse Block onpage 6-104. Access to the battery is not necessary tojump start the vehicle. SeeJump Starting on page 6-36.
6-34
Tire Sidewall Labeling
Useful information about a tire is molded into itssidewall.
(A) Tire Size:The tire size is a combination ofletters and numbers used to define a particulartire’s width, height, aspect ratio, construction typeand service description. See the “Tire Size”illustration later in this section for more detail.
(B) TPC Spec (Tire Performance CriteriaSpecification):Original equipment tires designedto GM’s specific tire performance criteria havea TPC specification code molded onto the sidewall.GM’s TPC specifications meet or exceed allfederal safety guidelines.
(C) DOT (Department of Transportation):TheDepartment of Transportation (DOT) codeindicates that the tire is in compliance with theU.S. Department of Transportation Motor VehicleSafety Standards.
(D) Tire Identification Number (TIN):The lettersand numbers following the DOT code are theTire Identification Number (TIN). The TIN showsthe manufacturer and plant code, tire size,and date the tire was manufactured. The TIN ismolded onto both sides of the tire, althoughonly one side may have the date of manufacture.
Passenger Car Tire Example
6-47
(B) Tire Ply Material:The type of cord andnumber of plies in the sidewall and under thetread.
(C) Tire Identification Number (TIN):The TireIdentification Number (TIN). The TIN showsthe manufacturer and plant code, tire size, anddate the tire was manufactured. The TIN is moldedonto both sides of the tire, although only oneside may have the date of manufacture.
(D) Maximum Cold Inflation LoadLimit:Maximum load that can be carried and themaximum pressure needed to support thatload. SeeInflation - Tire Pressure on page 6-54andLoading the Vehicle on page 5-18.
(E) Tire Inflation:The temporary use tire orcompact spare tire should be inflated to 60 psi(420 kPa). For more information on tire pressureand inflation seeInflation - Tire Pressure onpage 6-54andSpare Tire on page 6-90.
(F) Tire Size:A combination of letters andnumbers define a tire’s width, height, aspect ratio,construction type and service description. Theletter T as the first character in the tire size meansthe tire is for temporary use only.
(G) TPC Spec (Tire Performance CriteriaSpecification):Original equipment tires designedto GM’s specific tire performance criteria havea TPC specification code molded onto the sidewall.GM’s TPC specifications meet or exceed allfederal safety guidelines.
6-49
(A) Tire Size:The tire size code is a combinationof letters and numbers used to define a particulartire’s width, height, aspect ratio, constructiontype and service description. See the “Tire Size”illustration later in this section for more detail.
(B) TPC Spec (Tire Performance CriteriaSpecification):Original equipment tires designedto GM’s specific tire performance criteria havea TPC specification code molded onto the sidewall.GM’s TPC specifications meet or exceed allfederal safety guidelines.
(C) Dual Tire Maximum Load:Maximum loadthat can be carried and the maximum pressureneeded to support that load when used in a dualconfiguration.
(D) DOT (Department of Transportation):TheDepartment of Transportation (DOT) codeindicates that the tire is in compliance with theU.S. Department of Transportation Motor VehicleSafety Standards.
(E) Tire Identification Number (TIN):The lettersand numbers following DOT code are the TireIdentification Number (TIN). The TIN showsthe manufacturer and plant code, tire size, anddate the tire was manufactured. The TIN is moldedonto both sides of the tire, although only oneside may have the date of manufacture.
Light Truck Tire Example
6-50
(F) Tire Ply Material:The type of cord andnumber of plies in the sidewall and underthe tread.
(G) Single Tire Maximum Load:Maximum loadthat can be carried and the maximum pressureneeded to support that load when used as asingle. For information on recommendedtire pressure seeInflation - Tire Pressure onpage 6-54.
Tire Size
The following illustration shows an example of atire size.
(A) P-Metric Tire:The United States version of ametric tire sizing system. The letter P as thefirst character in the tire size means a passengervehicle tire engineered to standards set by theU. S. Tire and Rim Association.
(B) Tire Width:The three-digit number indicatesthe tire section width in millimeters from sidewallto sidewall.
(C) Aspect Ratio:A two-digit number thatindicates the tire height-to-width measurements.For example, if the tire size aspect ratio is60, as shown in item C of the illustration, it wouldmean that the tire’s sidewall is 60 percent ashigh as it is wide.
(D) Construction Code:A letter code is used toindicate the type of ply construction in the tire.The letter R means radial ply construction;the letter D means diagonal or bias plyconstruction; and the letter B means belted-biasply construction.
(E) Rim Diameter:Diameter of the wheel ininches.
(F) Service Description:These charactersrepresent the load index and speed rating of thetire. The load index represents the load carrycapacity a tire is certified to carry. The speedrating is the maximum speed a tire is certified tocarry a load.
6-51
Tire Terminology and Definitions
Air Pressure:The amount of air inside thetire pressing outward on each square inch of thetire. Air pressure is expressed in pounds persquare inch (psi) or kilopascal (kPa).
Accessory Weight:This means the combinedweight of optional accessories. Some examples ofoptional accessories are, automatic transmission,power steering, power brakes, power windows,power seats, and air conditioning.
Aspect Ratio:The relationship of a tire’s heightto its width.
Belt:A rubber coated layer of cords that is locatedbetween the plies and the tread. Cords may bemade from steel or other reinforcing materials.
Bead:The tire bead contains steel wires wrappedby steel cords that hold the tire onto the rim.
Bias Ply Tire:A pneumatic tire in which the pliesare laid at alternate angles less than 90 degreesto the centerline of the tread.
Cold Tire Pressure:The amount of air pressure ina tire, measured in pounds per square inch (psi) orkilopascals (kPa) before a tire has built up heatfrom driving. SeeInflation - Tire Pressure onpage 6-54.
Curb Weight:The weight of a motor vehicle withstandard and optional equipment including themaximum capacity of fuel, oil, and coolant,but without passengers and cargo.
DOT Markings:A code molded into the sidewallof a tire signifying that the tire is in compliancewith the U.S. Department of Transportation (DOT)motor vehicle safety standards. The DOT codeincludes the Tire Identification Number (TIN),an alphanumeric designator which can also identifythe tire manufacturer, production plant, brand,and date of production.
GVWR:Gross Vehicle Weight Rating. SeeLoading the Vehicle on page 5-18.
GAWR FRT:Gross Axle Weight Rating for thefront axle. SeeLoading the Vehicle on page 5-18.
GAWR RR:Gross Axle Weight Rating for therear axle. SeeLoading the Vehicle on page 5-18.
Intended Outboard Sidewall:The side of anasymmetrical tire, that must always face outwardwhen mounted on a vehicle.
Kilopascal (kPa):The metric unit for air pressure.
Light Truck (LT-Metric) Tire:A tire used onlight duty trucks and some multipurpose passengervehicles.
6-52
If you need to replace any of your wheels, wheel bolts,wheel nuts, or Tire Pressure Monitor System (TPMS)sensors, replace them only with new GM originalequipment parts. This way, you will be sure to have theright wheel, wheel bolts, wheel nuts, and TPMSsensors for your vehicle.
{WARNING:
Using the wrong replacement wheels, wheel bolts,
or wheel nuts on your vehicle can be dangerous. It
could affect the braking and handling of your
vehicle, make your tires lose air and make you
lose control. You could have a collision in which
you or others could be injured. Always use the
correct wheel, wheel bolts, and wheel nuts for
replacement.
Notice:The wrong wheel can also cause problemswith bearing life, brake cooling, speedometer orodometer calibration, headlamp aim, bumper height,vehicle ground clearance, and tire or tire chainclearance to the body and chassis.
If your vehicle is a professional model, the wheels havea unique offset and bolt hole diameter. Each of thewheels on the professional vehicle have eight wheelsnuts. The wheels on the non-professional vehiclehave five wheel nuts. SeeChanging a Flat Tire onpage 6-80for more information.
Used Replacement Wheels
{WARNING:
Putting a used wheel on the vehicle is dangerous.
You cannot know how it has been used or how far
it has been driven. It could fail suddenly and
cause a crash. If you have to replace a wheel, use
a new GM original equipment wheel.
6-69