Tires, Page 3 of 4
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Tire care Caring for tires is easy and important for safety, but many vehicle owners neglect this important part of vehicle maintenance. A survey by a major tire manufacturer found that: - Nine of every 10 vehicles inspected had improperly inflated tires.
- One of every five vehicles inspected had at least one tire with too little tread for safe use.
- One of every 20 tires inspected was in danger of imminent failure.
- Nearly one of every five tires inspected showed unusual tread wear due to alignment, improper inflation or improper balance.
Tire maintenance intervals
For maximum wear and safety from your tires, they should be maintained at the follow intervals.
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1. Rotate Tires
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Every 6 months/6000 miles
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2. Check tire pressure
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Every fuel stop/2 weeks
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3. Check tread depth
tread of stones, glass, debris
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Every 6 months/6000 months
As necessary
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Inflation and inspection
See Figures 14 thru 25 The importance of proper tire inflation cannot be over-emphasized. A tire employs air as part of its structure. It is designed around the supporting strength of the air at a specified pressure. For this reason, improper inflation drastically reduces the tire's ability to perform as intended. A tire will lose some air in day-to-day use; having to add a few pounds of air periodically is not necessarily a sign of a leaking tire. Two items should be a permanent fixture in every glove compartment: an accurate tire pressure gauge and a tread depth gauge. Check the tire pressure (including the spare) regularly with a pocket type gauge. Too often, the gauge on the end of the air hose at your corner garage is not accurate because it suffers too much abuse. Always check tire pressure when the tires are cold, as pressure increases with temperature. If you must move the vehicle to check the tire inflation, do not drive more than a mile before checking. A cold tire is generally one that has not been driven for more than three hours.
Figure 14 A variety of high-quality pressure gauges are available. Get one and use it often.
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Figure 15 Tires should be checked frequently for any sign of puncture or damage.
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Figure 16 Tires with deep cuts, or cuts which show bulging should be replaced immediately.
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Figure 17 Examples of inflation-related tire wear patterns.
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Figure 18 Tire inflation pressure is a major factor in determining how long your tires last and how well they perform.
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Figure 19 The rolling resistance of a tire decreases dramatically as the inflation pressure increases.
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Figure 20 Radial tires have a characteristic sidewall bulge. Don't try to measure pressure by looking at the tire. Use a quality air pressure gauge.
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Figure 21 Common tire wear patterns and causes.
Click on the picture for a larger view.
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A plate or sticker is normally provided somewhere in the vehicle (door post, hood, tailgate or trunk lid) which shows the proper pressure for the tires.
Never exceed the maximum tire pressure embossed on the tire! This is the pressure to be used when the tire is at maximum loading, but it is rarely the correct pressure for everyday driving. Consult the owner's manual or the tire pressure sticker for the correct tire pressure. Once you've maintained the correct tire pressures for several weeks, you'll be familiar with the vehicle's braking and handling personality. Slight adjustments in tire pressures can fine-tune these characteristics, but never change the cold pressure specification by more than 2 psi (14 kPa). A slightly softer tire pressure will give a softer ride but also yield lower fuel mileage. A slightly harder tire will give crisper dry road handling but can cause skidding on wet surfaces. Unless you're fully attuned to the vehicle, stick to the recommended inflation pressures. All tires made since 1968 have built-in tread wear indicator bars that show up as 1/2 inch (13mm) wide smooth bands across the tire when 1/16 inch (1.5mm) of tread remains. The appearance of tread wear indicators means that the tires should be replaced. In fact, many states have laws prohibiting the use of tires with less than this amount of tread.
Figure 22 A plate or sticker is normally provided somewhere in the vehicle (door post, hood, tailgate or trunk lid) which shows the proper pressure for the tires.
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Figure 23 Tread wear indicators will appear when the tire is worn.
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Figure 24 Accurate tread depth indicators are inexpensive and handy.
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You can check your own tread depth with an inexpensive gauge or by using a Lincoln head penny. Slip the Lincoln penny (with Lincoln's head upside-down) into several tread grooves. If you can see the top of Lincoln's head in 2 adjacent grooves, the tire has less than 1/16 inch (1.5mm) tread left and should be replaced. You can measure snow tires in the same manner by using the "tails'' side of the Lincoln penny. If you can see the top of the Lincoln memorial, it's time to replace the snow tire(s).
Figure 25 A penny works well for a quick check of tread depth.
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Rotating the tires
See Figures 26, 27 and 28 Tire rotation is important for even tread wear and long life. When performed at the recommended times, it will ensure that the tires wear evenly and prolong the useful life of the tires. Tires should be rotated at regular intervals. Tires can be rotated conveniently during every other regular oil change, which for most vehicles, would put rotation at about every 5000-7500 mi. (8000-12000 km). Front and rear, drive and non-drive tires exhibit different wear patterns. Front tires tend to wear in the shoulder area, because of steering and cornering forces. Drive tires tend to wear in the center because of drive traction forces. On front wheel drive vehicles, front tires wear faster then the rear. Personal driving habits and vehicle performance characteristics also cause tires to wear differently. Vehicles are designed to operate with a matched set of tires. When rotating "uni-directional tires,'' make sure that they always roll in the same direction. This means that a tire used on the left side of the vehicle must not be switched to the right side and vice-versa. Such tires should only be rotated front-to-rear or rear-to-front, while always remaining on the same side of the vehicle. These tires are marked on the sidewall as to the direction of rotation; observe the marks when reinstalling the tire(s). There are many tire rotation patterns. Any routine pattern is better than no rotation at all. The important factor in a tire rotation pattern is that all tires eventually are placed at all applicable wheel positions. If the vehicle is equipped with a full size spare, it should be included in the rotation pattern. The tires on your vehicle according to the following rules: - On front wheel drive vehicles, rotate the tires in forward cross pattern (move the drive tires straight to the rear then, cross the rear tires and mount on the front) or a regular cross pattern.
- On rear wheel or four wheel drive vehicles, rotate the tires in a rearward cross pattern (move the drive tires straight to the front then, cross the front tires and mount on the rear) or a regular cross pattern.
- If the vehicle is equipped with directional wheels or tires, rotate them from the front to back.
- If the vehicle is equipped with non-directional tires that are different size from front to rear, rotate them from the side to side.
Figure 26 Common tire rotation patterns for 4- and 5-wheel rotations.
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Figure 27 Compact spare tires must NEVER be used in the rotation pattern.
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Figure 28 Uni-directional tires are identifiable by sidewall arrows and/or the word "rotation."
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Some styled or "Mag" wheels may have different offsets front to rear. In these cases, the rear wheels must not be used up front and vice-versa. Furthermore, if these wheels are equipped with uni-directional tires, they cannot be rotated unless the tire is remounted for the proper direction of rotation. The compact or space-saver spare is strictly for emergency use. It must never be included in the tire rotation or placed on the vehicle for everyday use. Some years ago, many manufacturers believed that radials should be treated as directional tires in order to prevent rapid wear and possible handling difficulties. But, over the years most tire and vehicle manufacturers (even ones that formerly warned against cross-switching radials) began to change their tune. Now most vehicle and tire manufacturers recommend including radials in rotational patterns which switch the direction of tire rotation. Storing the tires If they are mounted on wheels, store the tires at proper inflation pressure. All tires should be kept in a cool, dry place. If they are stored in the garage or basement, do not let them stand on a concrete floor; set them on strips of wood, a mat or a large stack of newspaper. Keeping them away from direct moisture is of paramount importance. Tires should not be stored upright, but in a flat position.
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©1998 W. G. Nichols - Chilton's Easy Car Care
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