Your vehicle’s tires are the only part of the car that has direct contact with the road. Your tires will affect your vehicle’s handling, ride, braking, and even safety. For maximum performance, your tires must have the correct air pressure, tread depth, balance and the wheels must be aligned properly. Having your tires checked on a regular basis is an important step to protecting your automotive investment and safety. Tire inspections should be performed monthly or if your TPMS (Tire Pressure Monitor Sensor) light comes on alerting you your tire pressure is too low. If the light is illuminated, it means your tires could be under inflated. It is important to understand the importance of keeping your tires properly inflated. If you drive over potholes and debris in the road, live in a cold climate, or drive long distances regularly, then you should have your tires inspected more often.
Signs of Tire Wear
Always have your tires inspected before a long trip. The more often these inspections are performed, the easier it will be to find a small problem, such as a nail in your tire, and fix it before it becomes a more expensive issue. Poor maintenance of tires can lead to premature wear, a flat or even a blowout. However other factors can affect tire wear, such as worn suspension parts and wheel alignment.
Tire Problems to Look For During a Visual Inspection
- Over inflation: Too much air pressure causes the tire’s middle section to contact the road. This creates wear primarily in the center of the tread, with less wear at the tire’s edges.
- Under inflation: Too little air pressure causes the tire’s outer edges to contact the road. This creates wear primarily on both edges of the tire tread, with less wear in the center.
- Tread wear on one edge of the tire: This typically occurs when the wheels are out of alignment.
- Erratic tread wear: This is usually called cupping, and may mean your wheel is out of balance, or that your shocks or other suspension components may need replaced.
- Raised portion of the tread or sidewall: May indicate that one of the belts in the tire has separated and needs to be replaced.
Tire Problems to Look for While Driving
- Unusual vibration or thumping: Vibration or thumping noises can indicate an out-of-balance tire, one with tread that has a flat spot due to locking the wheels in a panic stop, or a tire with a separated belt.
- Pulls to one side: While driving at a steady speed, pulling to one side could indicate an under inflated or damaged tire on the side of the car to which the vehicle pulls. If this is not the case, a brake problem or poor wheel alignment may also be causing the pull.
Tire Tread Inspection
Tires count on good tread condition and depth to maintain traction and to shed water on wet roads. The tread should be checked at least once a month for excessive and uneven wear. The most accurate tread depth measurements are made with a tread depth gauge our technicians use in our Certified Service Department. For checking at home you can use the traditional quarter and penny tests, or pickup a basic tread depth gauge available at any auto parts store.
Inserting a quarter into a tread groove with the top of Washington’s head facing down. If the top of his head is not visible, your tires have at least 4/32” of tread and are fine for continued use. If you can see above the top of Washington’s head, it is time to start shopping for new tires. Take measurements in three locations across the tire’s tread: (1)outer edge, (2) center, and (3) inside edge.
The penny test is done in the same way, except that if you can see above the top of Lincoln’s head your tires have less than 2/32” of tread, which is below the legal minimum and cause for immediate replacement. Tires worn to this level will also have visible wear indicators (thin bald strips) running from side to side across two or more tread segments.
The difference between 4/32” and 2/32” of tread depth might not seem like much, but the difference is significant. For example, a Silverado truck traveling at 70 miles per hour that passes the penny test can take up to 500 feet to stop on wet pavement . However, the same truck has a stopping distance 125 feet shorter if it passes the quarter test instead. This is a significant difference in stopping distance, and the equivalent of six or more car lengths. Given these facts, we suggests you put that penny back in your piggy bank and instead use a quarter to check tire wear, if you do so from home to determine when it is time for replacement.
Tires Inflation At-Home Inspection
Keeping your tires properly inflated is one of the easiest ways to help maintain good gas mileage and extend the life of your tires. Check your car’s tire pressure at least once a month with a quality gauge, that measures pressure in pounds-per square inch (psi). Three types of tire pressure gauges are available at most auto parts stores: digital, dial and pen/stick types. The digital and dial designs tend to be more accurate and easier to read, although a good pen/stick gauge will do the job as well. Pressure gauges built into air hoses at gas stations are often abused and frequently inaccurate.
Recommended tire pressures are for cold tires. Therefore, tire pressure should be checked at ambient temperature before the vehicle has been driven. Checking tire pressure on a car that has warm tires can result in a pressure reading of up to 5 psi higher than the recommended pressure. The recommended inflation pressures for your car’s tires can be found in the vehicle’s owner’s manual or on the tire information decal attached to the driver’s door jamb. On older cars the decal may be in the glove box or inside the fuel filler door.
Checking Air Pressure
- Remove the tire’s valve cap.
- Place the gauge over the tire’s valve stem and press firmly so that no escaping air is heard. The tire gauge will indicate how much pressure is in the tire.
- Adjust the tire’s air pressure as needed. When adding air, push the air hose into the valve firmly, until the air stops escaping. Check the pressure every few seconds to help judge the amount of air going into the tire, until you reach the recommended air pressure. If the tire’s pressure is greater than it should be, use the nipple on the tire gauge to press the center of the tire valve stem and release air.
- Replace the valve cap.
- Repeat the process for the other tires. Don’t forget the spare tire.
Tire Rotation, Balancing, Alignment
There are several tire maintenance procedures that automotive repair professionals should do because they require special tools and knowledge. However, understanding these procedures will help you feel more confident in dealing with a repair provider.
Tires on the front and the rear of vehicles operate at different loads and perform different steering and braking functions, resulting in unequal wear patterns. To gain maximum life and performance from your tires, it is essential to rotate your vehicle’s tires. Refer to your vehicle’s owner’s manual for mileage recommendations. For most GM vehicles Usually tire rotation is performed between 6,000 and 7,500 miles (with every oil change). If you have a performance cars those tires are designed to rotate in a specific direction; they can only be rotated front-to-rear, and if different tire sizes are used on the front and rear axles rotation is not possible.
A properly balanced tire will help minimize uneven wear and extend the life. When tires are balanced, small weights are attached to the wheels to limit vibration of the tire and wheels as they turn. Newly installed tires should be balanced, and thereafter whenever a vibration is noticed. Balancing is also done whenever a tire is removed from the wheel, for example to repair a puncture.
Wheel alignment is the measurement of the position of the wheels compared to specifications that the vehicle manufacturers recommend. Each vehicle has specific wheel alignment settings. If any alignment measurement falls outside the specified range, uneven tire wear can result, vehicle handling may be affected and fuel economy can be diminished.
You should have the wheel alignment checked and adjusted when new tires are installed, and thereafter any time when unusual steering characteristics are observed. A vehicle’s wheels are properly aligned when the car will drive down the road in a straight line without drifting or pulling to either side. A pull can be caused by problems other than just alignment, we suggest you Make An Appointment with our Service Department, so a thorough inspection can be performed to determine the exact nature of the problem before an alignment is performed. Spending a few minutes with your tires every month can help protect your family, improve your vehicle’s performance, and lengthen the life of your tires.