Tire Maintenance Guide
Tires are one of the most vital safety components for any car. They provide the vehicle's only point of contact to the road. Tire grip is what keeps a car on the road when it goes around a corner at speed; tires also carry the entire stopping force of the brakes. Driving with tires that need replacing can be like driving in snow or ice even in perfect road conditions, and that can be dangerous for both drivers and for everyone around them. It is also important to check for under and over inflation as either can be damaging to the tires, under inflation more so than over inflation. With so much potential for damage or disaster, regular tire inspections should be a part of every car owner's maintenance program. Drivers should check tire pressure at least once per month and have the tires professionally inspected during each oil change or when the tires are rotated. Combining tire inspection with other routine maintenance tasks ensures it does not get overlooked.
Things to Look for During a Tire Inspection
There was a time when inspecting tires consisted of nothing more than walking around the car once and giving each tire a solid kick. While the classic "kicking the tires" methodology is a wonderful image, it simply cannot provide the information needed to determine whether tires need replacing. All it can really do is give a rough guess as to inflation, and an inexpensive tire gauge is much more accurate than anyone's right shoe. To really understand the condition of a set of tires, one needs to check much more than the approximate tire pressure.
Check Tire Pressure
The first thing to check, and something that should be checked most often, is the tire pressure. Every car has an information plate, usually inside the driver's door, which shows the manufacturer's recommended tire pressures for that vehicle. While many tires do have a pressure figure listed on the sidewall, this is the maximum pressure the tire is designed to withstand, not the recommended inflation level. Always take the inflation figures from the car, not from the tires.
The following table shows some of the problems that can result from incorrect tire inflation.
|Under-inflation||Reduced gas mileage|
|Under-inflation||Tire failure due to additional stress on sidewalls|
|Under-inflation||Reduced handling due to tires flexing|
|Under-inflation||Increased tread wear|
|Over-inflation||Harsher ride and increased stress on suspension|
|Over-inflation||Increased chance of blowout|
Inspect for Tread Wear
One of the most important checks to perform when doing a tire inspection is the condition of the treads on all four tires. While tread wear is particularly important on the drive wheels, which are the front wheels on most cars, it does matter for all tires because treads are important for both braking and handling as well as drive and steering.
The first thing to check is uneven tread wear. If the tires are wearing more on one side or the other, this is a sign that they are under stress and are more likely to fail. The next thing to look at is tread depth. Most tires have smooth bars that run across the grooves in the tread, which serve as an indicator of when the tire must be changed. If the tread is worn down to the point where it is level with the bar, it is time to replace the tire immediately. One way to check tread depth is with a U.S. Lincoln head penny. If the penny can be inserted far enough into the groove to cover the top of Lincoln's head, the tire is still good. If not, it should be changed. The final thing to check is for foreign objects in the tread. Owners should go through and remove any debris, such as small rocks or bits of glass that might be caught in the tread, as tire wear could force them deeper into the tire, and possibly lead to a puncture.
Check for Visible Tire Damage
Visible damage is a clear sign that a tire needs to be repaired or preferably replaced. Every tire inspection should involve a complete visual inspection for damage. This damage can include, but is not limited to, such things as obvious splits, cracks, and punctures in the casing as well as bulges in the sidewall. The presence of any of these signs is a clear indication that the tire is near the very end of its useful life and that it is time to replace it. While punctures may be repaired, many other types of visible damage may be signs of further damage to the tire's interior which could have compromised its structural integrity without the owner knowing.
Check the Valve Stems
They may seem like small things, but the valve stems are very important. The first thing to look for is the presence of a valve cap. They may be small, but valve caps perform a vital function in keeping the valves clean and preventing slow leaks. Even a small amount of soil in the valve can lead to a slow leak, which can then mean a persistent under-inflation problem. Not only should the valve stems be checked regularly for leaks, but it is also important to replace any missing valve caps as soon as their absence is noticed.
Tire Inspection Frequency
While different manufacturers may have their own individual recommendations for tire inspection frequency, it is a good idea to at least check the tire pressure once a month and do a full inspection with every tire rotation, if not more frequently. As with anything else, it is easier to remember to do a full inspection if it is done at the same time as other scheduled procedures. One way to do that is to inspect the tires with every oil change. That way, the very longest someone is likely to go between inspections is 3,000 to 5,000 miles.
Inspect With Every Tire Rotation
Many drivers regularly rotate their tires, either from front to back on the same side for unidirectional tires or diagonally from left front to right rear with regular tires. Many drivers do this every few thousand miles or so, while others may wait until they replace the front tires and move the old ones to the rear at that time. Whatever system a car owner follows, it is important to inspect the tires whenever they are rotated to ensure that damaged tires are replaced or repaired rather than simply moved.
Watch Out for Slow Leaks
Any time a driver finds that he or she is putting air in one or more tires on a weekly or more frequent basis, a complete tire inspection is in order. While tires do tend to lose air over time, they do not normally lose air so quickly as to require re-inflation on a weekly basis. This is a clear sign of tire damage and should be dealt with as quickly as possible.