RESEARCH

Tires age when stored normally mounted on a parked vehicle. Park a vehicle that will be stored for at least a month in a cool, dry, clean area away from direct sunlight to slow aging. The area should be free of grease, gasoline, or other substances that can deteriorate rubber. This also applies to unmounted tires.

Parking for an extended period can also cause flat spots that may result in vibrations while driving. When storing a vehicle for more than a month, remove the tires or raise the vehicle to reduce the weight from the tires.

If your GMC vehicle has a Tire Pressure Monitoring System, it will need to be reset after each tire rotation. See your Owner’s Manual for details.

Proper wheel alignment is key to the life of your tires. If your vehicle is misaligned, it can cause your tires to wear unevenly, and you may experience handling problems such as pulling or abnormal vibration.

Tires and wheels are aligned and balanced at the factory to help provide best overall performance. Adjustments to wheel alignment and tire balancing are not necessary on a regular basis. Consider a wheel alignment check if there is unusual tire wear or if your GMC vehicle is significantly pulling to one side or the other.

A tire that is out of balance often affects ride quality and can shorten the life of tires, bearings, shocks, and other suspension components. If the vehicle is vibrating when driving on a smooth road, the tires and wheels may need to be rebalanced.

Caster is the tilting of the uppermost point of the steering axis either forward or backward, when viewed from the side of the vehicle. A backward tilt is positive and a forward tilt is negative. Caster influences directional control of the steering but does not affect tire wear. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster.

• With too little positive caster, steering may be touchy at high speeds and wheel returnability may be diminished when coming out of a turn.
• If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.

Always visit a Certified Service expert technician if you experience any of these situations. Check your Owner’s Manual for more information about wheel alignment and tire balance on your specific vehicle.

Air is a gas, expanding when heated and contracting when cooled. For most of North America, fall and early winter are especially important times for checking tire pressure on your GMC vehicle – as the ambient temperature falls, tire pressure goes down. A good rule of thumb: with every 10 degrees Fahrenheit of temperature change, tire pressure changes about 1 psi–higher as temperatures rise, lower as they fall.

Check your GMC tires at least once a month when the tires are cold, meaning the vehicle has not been driven for at least 3 hours or no more than 1 mile. The Tire Information Label located on the inside of your vehicle’s door frame has the recommended cold tire pressure for your GMC vehicle. Use a quality gauge. Don’t try to eyeball it - radial tires may appear fine even when they’re underinflated. Look for objects that can get wedged in the tread—they’ll work themselves even further into the tire and cause air loss. To make sure you’re covered, every check of your tires should include a check of your spare (if available), as well.

If the Tire Pressure Monitor light illuminates and stays solid with a Check Tire Pressure, Low Tire Pressure, or Add Air To Tire message, then check and adjust all tire air pressures to the recommended levels. Next, drive the vehicle to turn the light off.

If the Tire Pressure Monitor light appears as a blinking yellow lamp for more than one minute and stays solid, then diagnostic service is needed. If your TPMS is not functioning properly, it cannot detect or signal a low-tire condition.