GM Service Manual Online
For 1990-2009 cars only

The following tire qualities are designed in order to obtain maximum length of service under normal operating conditions:

    • The fabric
    • The rubber
    • The bead
    • The contour
    • The size of tires used on these vehicles

The tires operate efficiently only on a specified amount of air. Unless the driver of the vehicle maintains the correct air pressure, the tires will not function as intended.


Object Number: 203217  Size: SH

An underinflated tire may cause the vehicle to operate in the following manners:

    • Runs sluggishly
    • Heats up quickly because of the greater flexing
    • Bruises more often

In dual tire mounting, loss of pressure in one tire could cause the tire to slip on the wheel.


Object Number: 203219  Size: SH

Overinflation may weaken the tire, causing a blow-out. Improperly inflated tires will affect the following conditions:

    • Steering
    • Riding comfort
    • Safe driving

Object Number: 203215  Size: SH

Inflate the tires as indicated by the manufacturer's recommendation:

    • For greater riding comfort
    • For longer tire life
    • To reduce vehicle chassis wear

Ensure that the combined front and rear tire load do not exceed the maximum recommended load.

Inflate the tires to the recommended pressure when the tires are cool. If the tires are always carrying less than the recommended maximum load, reduce the air pressure to correspond with the actual load carried.

Never bleed the tires in order to relieve pressure buildup. Tire temperature and air pressure will increase when the tire is in service. Tire design allows for this buildup in pressure. Tire temperature and air pressure will stay within limits that are not harmful to the tire when used with the recommended load and air pressure.

The followings conditions may be responsible for high pressure buildup:

    • Overload
    • Underinflation
    • Speed
    • A combination of these

Use the size and type of tire that has the capacity to carry the load at a recommended cold starting pressure.

Pressure Loss

At periodic intervals, use an accurate gage in order to check each tire for pressure loss. If you notice a pressure loss in any of the tires, complete the following steps:

  1. Make an inspection.
  2. Determine the cause of the pressure loss.
  3. Correct the problem.

Balanced Inflation

All tires on the same axle should always carry the same air pressure. Although a difference in air pressure of the rear and the front tires may be allowed, within certain limitations, you should not tolerate a difference in pressures between the right and the left tires on the same axle.

A 34 kPa (5 psi) underinflated tire can lower the efficiency of most brakes. Balanced tire inflation contributes to the following conditions:

    • Easier steering
    • Riding comfort
    • Driving safety
    • Minimum fuel use
    • Maximum tire mileage

Tire Overheat

As a tire becomes heated, the air in the tire expands and the air pressure rises. This is a normal condition, unless the pressure buildup is excessive. Increased tire pressure over 138 kPa (20 psi) is excessive. Increased tire pressure indicates the following conditions:

    • Underinflation
    • Overload
    • Too much speed
    • Too small a tire
    • More often, a combination of these factors

Investigate pressure buildups of over 138 kPa (20 psi) in order to determine the cause of the buildups. Take proper corrective action. Normal pressure buildups, not over 138 kPa (20 psi), reduce flexing.

Heat balance is defined as the temperature at which the rate of heating equals the rate of cooling. Normal pressure buildup reaches this heat balance at a lower temperature than by frequently bleeding the air in order to maintain the inflation pressure. Never bleed the tires. When the pressure builds up excessively, reduce the speed or the load.