Wheels and Tires: Description and Operation
TIRESGENERAL INFORMATION
All models are equipped with metric sized steel belted radial tires designed to operate satisfactorily with loads up to full-rated load capacity, when inflated to the recommended inflation pressures.
Correct tire pressure, wheel alignment, and driving technique significantly influence tire life. Excessively heavy cornering, accelerating and braking will increase tire wear and significantly decrease tire tread life.
INFLATION PRESSURE
For tire pressure and maximum tire load rating specification values, refer to tire loading information sticker located on rear edge of driver's side rear door.
The metric unit for tire inflation pressure is the Kilopascal (kPa), although inflation pressures are usually given in both kPa and psi. To convert between kPa and psi, use the following conversion formula:
1 psi = 6.9 kPa
NOTICE: Tire valve caps must always be installed onto the tire valve to keep dirt and moisture out of valve.
Maintaining correct tire inflation pressure is essential to proper vehicle performance. The specified inflation pressure is carefully calculated to provide satisfactory ride, stability, precise steering, acceptable tire wear, and resistance to road damage.
Tire inflation pressure should be checked when tires are cold. Cold tires are defined as tires on a vehicle that has not been driven for at least three hours or more than one mile.
It is normal for tire inflation pressure to increase 28 kPa (4 psi) as vehicle is driven distances more than one mile, as the tires heat up. Therefore, on a vehicle with warm tires, never attempt to correct tire pressure by letting air out of the tire; wait until the tire cools down to check and adjust tire pressure. Letting air out of a warm tire reduces cold inflation pressure.
TIRE WEAR
Irregular and premature tire wear has many causes, the most common being incorrect cold tire inflation pressure, incorrect wheel alignment, lack of tire rotation and worn suspension parts. These conditions can often be diagnosed by visually inspecting the tire tread for the following telltale symptoms:
INCORRECT COLD TIRE INFLATION PRESSURE
Tread wear at center of tire (over-inflation).
^ Frequent, aggressive acceleration.
^ Cold tire inflation pressure too high.
Tread wear on edges of tire (under-inflation).
^ Hard cornering.
^ Cold tire inflation pressure too low.
^ Lack of rotation.
INCORRECT WHEEL ALIGNMENT
^ Tread is worn on one side of the tire more than the other.
^ Tread blocks have scuffed, feathered or cupped appearance.
LACK OF TIRE ROTATION
^ Front tires worn more than rear tires.
WHEEL/TIRE IMBALANCE
Worn Suspension Parts
^ Wheel bearing looseness.
^ Front suspension loose/worn.
^ Steering parts loose/worn.
^ Front control arm ball stud or bushing loose or worn.
^ Strut dampers worn or damaged.
TREAD WEAR INDICATORS
The original equipment tires specified for Saturn vehicles have built in tread wear indicators to warn when tires need replacement. These indicators are wide bands located beneath the tread surface at the maximum tread wear depth. Tires are determined to be worn when indicator band appears across two or more tread grooves at three locations about the circumference of the tire.
TIRE REPLACEMENT
All models are equipped with metric sized steel belted radial tires. The metric tire size format is shown in the illustration. When replacement is necessary, the original equipment type tire should be used.
Refer to Tire Loading Information sticker located on rear edge of driver's side rear door.
Most metric tire sizes do not have exact corresponding alphanumeric tire sizes. Replacement tires should be of same size, load range, and construction as those originally equipped with vehicle. The use of any other size or type tire may affect vehicle ride and handling, speedometer/odometer calibration, vehicle ground clearance, tire to body or chassis clearance, and snow chain to body or chassis clearance.
NOTICE: Do not mix tires or wheels of different size or construction on vehicle. Vehicle handling may be seriously affected. A loss of control could occur.
It is recommended that new tires be installed in pairs on the same axle. If necessary to replace only one tire, it should be paired with tire having the most tread to equalize braking traction.
COMPACT SPARE TIRE
CAUTION: THE COMPACT SPARE TIRE SHOULD BE USED ONLY ON VEHICLES ORIGINALLY EQUIPPED WITH A COMPACT SPARE TIRE. USE OF A COMPACT SPARE TIRE ON A VEHICLE NOT DESIGNED TO USE ONE CAN RESULT IN VEHICLE DAMAGE OR LOSS OF VEHICLE CONTROL.
Saturn vehicles are equipped with a high pressure, compact spare tire. This type of spare tire is mounted on a narrow (four inch wide) rim.
NOTICE: Do not attempt to mount standard tires, snow tires, wheel covers, trim rings, or other accessories to compact wheel. Doing so may damage these items or other parts of vehicle.
The correct inflation pressure for compact spare tire is 415 kPa (60 psi). The tire should be checked periodically for correct inflation pressure.
The compact spare tire is mounted and dismounted in the same manner as the standard tires equipped on the vehicle.
WHEELS IDENTIFICATION
Steel Wheel
Wheel identification information for steel wheels is located on inside face of the wheel.
Aluminum Wheel
Identification information for the aluminum wheels is located on outside face of the wheel.
WHEEL REPLACEMENT
Wheels and Wheel Bolts
A wheel must be replaced if it:
^ Is bent or dented.
^ Has excessive lateral or radial runout.
^ Leaks air through its welds.
^ Has stretched or oblong fastener holes or wheel bolts will not maintain proper torque value.
^ Is excessively rusty, particularly in bead flange area.
NOTICE: Do not mix tires or wheels of different size or construction on vehicle. Vehicle handling may be seriously affected. A loss of control could occur.
Replacement wheels must be equivalent to original equipment wheels in load capacity, diameter, rim width, offset, and mounting configuration. A wheel of improper size or type may affect wheel and bearing life, brake cooling, speedometer/odometer calibration, vehicle ground clearance, and tire clearance to body and chassis.
Wheel fasteners are critical components. If fasteners are replaced with those of incorrect specification, vehicle damage can occur and vehicle safety can be compromised. Always replace wheel fasteners with either items of the same part number or fasteners that are known to be equivalent in design to those originally supplied on vehicle.