Wheels and Tires: Description and Operation
General Description
The factory installed tires are designed to operate satisfactorily with loads up to and including the full rated load capacity when these tires are inflated to the recommended pressures.
The following factors have an important influence on tire life:
^ Correct tire pressures
^ Correct wheel alignment
^ Proper driving techniques
^ Tire rotation
The following factors increase tire wear:
^ Heavy cornering
^ Excessively rapid acceleration
^ Heavy braking
Description and Operation
Tread Wear Indicators Description
Tread Wear Indicators Description:
The original equipment tires have tread wear indicators that show when you should replace the tires.
The location of these indicators are at 72 degree intervals around the outer diameter of the tire. The indicators appear as a 6 mm (0.25 inch) wide band when the tire tread depth becomes 1.6 mm (2/32 inch).
Description and Operation
Metric Wheel Nuts and Bolts Description
Metric wheel/nuts and bolts are identified in the following way:
^ The wheel/nut has the word Metric stamped on the face.
^ The letter M is stamped on the end of the wheel bolt.
The thread sizes of metric wheel/nuts and the bolts are indicated by the following example: M12 x 1.5.
^ M = Metric
^ 12 = Diameter in millimeters
^ 1.5 = Millimeters gap per thread
Description and Operation
Tire Inflation Description
This vehicle has been engineered to operate up to the stated load capacity with wheel and tire assemblies of the type, size, construction, and configuration as originally installed. Maintenance of the tire inflation pressures is critical to the continued satisfactory performance, handling, and operating economy of the vehicle. Operation with incorrectly or improperly inflated tires can adversely affect vehicle performance and may contribute to the following:
^ Reduced fuel economy
^ Tire overloading
^ Shortened tire life
^ Excessive tire wear
^ Uneven tire wear
^ Vehicle handling concerns
Inspect the tire pressures when the vehicle has not been driven for at least 3 hours or not more than 1.6 km (1 mi) and when the tires are cool to the touch.
Tire inflation pressures should be inspected monthly and before an extended trip and adjusted to meet the specifications listed for the particular vehicle. Replace any missing or damaged tire valve stem extensions and/or caps to prevent the intrusion of water and contaminates.
Inflation Pressure Conversion (Kilopascals To PSI):
One pound per square inch (psi) equals 6.9 kilopascals (kPa). The following table illustrates the conversion of kilopascals to pounds per square inch:
For the correct inflation pressures refer to the vehicle's tire placard.
Tires inflated to a higher than recommended pressure can contribute to the following conditions:
^ A hard ride
^ Tire bruising
^ Rapid tread wear at the center of the tire
Tires inflated to a lower than recommended pressure can contribute to the following conditions:
^ Tire squeal on turns
^ Hard steering
^ Rapid and/or uneven wear on the outer edges of the tread
^ Tire rim bruises and tire rim rupture
^ Tire cord breakage
^ High tire temperatures
^ Sluggish vehicle handling
^ Higher fuel consumption
Unequal pressure on the same axle can cause the following conditions:
^ Uneven braking action
^ Steering lead
^ Imprecise vehicle handling
Description and Operation
Tire Chain Usage Description
Tire Chain Usage Description:
When you use tire chains, most current vehicles require the following chain types:
^ SAE Class S or 1100 Series, Type PL tire chains (1)
^ SAE Class U or 1200 Series, Type P tire chains (2)
^ 1800 Series Lug Reinforced tire chains (3)
These chains are specially designed in order to limit the fly-off effect that occurs when the wheel rotates.
Manufacturers of tire chains have a specific chain size for each tire size. These ensure a proper fit when the chains are installed. Purchase the correct chains for the tires on which the chains will be used. Do not use rubber adjusters to take up slack in chains that are loose due to incorrect size. Always follow the chain manufacturer's installation instructions.
The use of chains may adversely affect handling. When using chains, remember the following information:
^ Ensure that the vehicle is designed for chain clearance.
^ Adjust the speed to road conditions.
^ Avoid sharp turns.
^ Avoid locked-wheel braking in order to prevent chain damage to the vehicle.
^ Install the chains as tightly as possible on the drive tires. Tighten the chains again after driving 0.4 - 0.8 km (0.25 - 0.5 mi). Do not use chains on the non-drive tires. These chains may contact and damage the vehicle. If you use chains on the non-drive tires, ensure that there is enough clearance.
^ Do not exceed 70 km/h (45 mph). Do not exceed the chain manufacturer's speed limit, if lower.
^ Drive in a restrained manner. Avoid large bumps, potholes, severe turns, and other maneuvers that cause the tires to bounce up and down.
^ Follow any other instructions from the chain manufacturer that do not disagree with the above.
Description and Operation
All Seasons Tires Description
Most GM vehicles are equipped with steel belted all-season radial tires as standard equipment. These tires qualify as snow tires, with a higher than average rating for snow traction than the non-all season radial tires previously used. Other performance areas, such as wet traction, rolling resistance, tread life, and air retention, are also improved. This is done by improvements in both tread design and tread compounds. These tires are identified by an M + S molded in the tire side wall after the tire size. The suffix MS is also molded in the tire side wall after the TPC specification number.
The optional handling tires used on some vehicles now also have the MS marking after the tire size and the TPC specification number.
Description and Operation
P-Metric Sized Tires Description
P-Metric Sized Tires Description:
Most P-metric tire sizes do not have exact corresponding alphanumeric tire sizes. Replacement tires should be of the same tire performance criteria (TPC) specification number including the same size, the same load range, and the same construction as those originally installed on the vehicle. Consult a tire dealer if you must replace the P-metric tire with other sizes. Tire companies can best recommend the closest match of alphanumeric to P-metric sizes within their own tire lines.
Description and Operation
Replacement Wheels Description
Replace the wheel if any of the following conditions exist:
^ The wheel exhibits excessive runout.
^ The wheel is bent.
^ The wheel is cracked.
^ The wheel is severely rusted.
^ The wheel is severely corroded.
^ Important: Air leaks caused by porosity on aluminum wheels are repairable.
The wheel leaks air.
Caution: If you are replacing the wheel(s), the wheel stud(s), the wheel nut(s) or the wheel bolt(s), install only new GM original equipment parts. Installation of used parts or non-GM original equipment parts may cause the wheel to loosen, loss of tire air pressure, poor vehicle handling and loss of vehicle control resulting in personal injury.
Notice: The use of non-GM original equipment wheels may cause:
^ Damage to the wheel bearing, the wheel fasteners and the wheel
^ Tire damage caused by the modified clearance to the adjacent vehicle components
^ Adverse vehicle steering stability caused by the modified scrub radius
^ Damage to the vehicle caused by the modified ground clearance
^ Speedometer and odometer inaccuracy
Replace the wheel, the wheel studs and the wheel/nuts, or the wheel bolts if applicable, if any of the following conditions exist:
^ The wheel has elongated bolt holes.
^ The wheel/nuts, or bolts if applicable, loosen repeatedly.
Steel wheel identification is stamped into the wheel near the valve stem.
Aluminum wheel identification is cast into the inboard side of the wheel.
Description and Operation
Steel Wheel Repair Description
Notice: Do not heat wheels in an attempt to soften them for straightening or repair damage from striking curbs, etc. Do not weld wheels. The alloy used in these wheels is heat-treated and uncontrolled heating from welding affects the properties of the material.
Notice: The use of tubes in tubeless tires is not a recommended repair due to the fact that speed ratings are greatly reduced.
You can repair porosity in aluminum wheels. If leaks are found in a steel wheel, replace the wheel with a wheel of original equipment quality.