Common sense, good driving habits, and proper maintenance will afford maximum tire life. Fast starts, sudden stops and hard cornering causes premature tire wear and will shorten their useful life span. Make sure not to overload the vehicle or run with incorrect pressure in the tires. Both of these practices will increase tread wear.
For optimum tire life, keep the tires properly inflated, rotate them often and have the wheel alignment checked periodically.
Inspect the tires frequently. Be especially careful to watch for bubbles in the tread or sidewall, deep cuts or underinflation. Replace any tire with bubbles in the sidewall. If cuts are so deep that they penetrate to the cords, discard the tire. Any cut in the sidewall of a radial tire renders it unsafe. Also, look for uneven tread wear patterns that may indicate the front end is out of alignment, the shocks are worn, or that the tires are out of balance.
Tires must be rotated periodically to equalize wear patterns that vary with a tire's position on the vehicle. Tires will also wear in an uneven pattern as the front steering/suspension system wears to the point where the alignment should be reset.
Rotating the tires will ensure maximum life for the tires as a set. This avoids having to discard a tire early due to wear on only part of the tread. Regular rotation is required to equalize wear.
When rotating "unidirectional 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).
See Figures 1 and 2
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 unidirectional 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.
For maximum satisfaction, tires should be installed in sets of four. Mixing of different types (radial, bias-belted, fiberglass belted) must be avoided. In most cases, the vehicle manufacturer has designated a type of tire on which the vehicle will perform best. Always consider using the same type of tire that the manufacturer recommends.
When radial tires are used, tire sizes and wheel diameters should be selected to maintain ground clearance and tire load capacity equivalent to the original equipment tire. Radial tires should always be used in sets of four.
See Figure 3
When selecting tires, pay attention to the original size as marked on the tire. Most tires are described using an industry size code sometimes referred to as P-Metric. This allows the exact identification of the tire specifications, regardless of the manufacturer. If selecting a different tire size or brand, remember to check the installed tire for any sign of interference with the body or suspension while the vehicle is stopping, turning sharply or heavily loaded.
Good radial tires can be a big advantage in slippery weather, but in snow, a street radial tire does not have sufficient tread and tread depth to provide optimum traction and control. The small grooves of a street tire quickly pack with snow and the tire behaves much like a billiard ball on a marble floor. The more open, chunky tread of a snow tire will self-clean as the tire turns, providing much better grip on snow covered surfaces.
To satisfy municipalities requiring snow tires during weather emergencies, most snow tires carry either an M + S designation after the tire size stamped on the sidewall, or the designation "all-season". In general, no change in tire size is necessary when buying snow tires.
Most manufacturers strongly recommend the use of 4 snow tires on their vehicles for reasons of stability. If snow tires are fitted only to the drive wheels, the opposite end of the vehicle may become very unstable when braking or turning on slippery surfaces. This instability can lead to unpleasant endings if the driver can't counteract the slide in time.
Note that snow tires, whether 2 or 4, will affect vehicle handling in all non-snow situations. The stiffer, heavier snow tires will noticeably change the turning and braking characteristics of the vehicle. Once the snow tires are installed, it is important to re-learn the behavior of the vehicle and drive accordingly.
Consider buying extra wheels on which to mount the snow tires. Once done, the "snow wheels" can be conveniently installed and removed as needed. This eliminates the time to mount and remount tire onto the rims and potential damage to tires or wheels from seasonal removal and installation. Even if the vehicle has styled wheels, inexpensive steel wheels may be available. Although the look of the vehicle will change, the expensive wheels will be protected from salt, curb hits and pothole damage.
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, keep them away from appliances or heaters and 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.
INFLATION & INSPECTION
The importance of proper tire inflation cannot be overemphasized. A tire uses 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; such that 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 the corner garage is not accurate because it suffers too much use and 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 and is not in direct sunlight.
See Figures 4 through 9
A plate or sticker is normally provided somewhere in the vehicle (fuel filler door, driver door, post, hood, tailgate or trunk lid) which shows the proper pressure for the tires. Note that the recommended tire pressure will change based on vehicle load. Never counteract excessive pressure build-up by bleeding off air pressure (letting some air out). This will cause the tire to run hotter and wear quicker.
Once the correct tire pressure has been maintained for several weeks, the vehicle's braking and handling personality becomes more familiar and predictable. Slight adjustments in tire pressures can fine-tune these characteristics, but never run the tire with less or more pressure than what is recommended. Changing the cold tire pressure by more than 2 psi may completely change the handling characteristics of the vehicle. A slightly lower tire pressure provides a softer ride but also yields lower fuel mileage. A slightly higher tire pressure will give crisper dry road handling but can cause skidding on wet surfaces. Unless 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 in. (13mm) wide smooth bands across the tire when 1 / 16 in. (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.
See Figures 10 and 11
Ttread depth can be checked 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 the top of Lincoln's head is not visible in 2 adjacent grooves, the tire has less than 1 / 16 in. (1.5mm) tread left and should be replaced. Snow tires can be measured in the same manner by using the "tails" side of the Lincoln penny. If the top of the Lincoln memorial is not visible, it's time to replace the snow tire(s).
See Figure 12
CARE OF SPECIAL WHEELS
If you have invested in magnesium, aluminum alloy or sport wheels, special precautions should be taken to make sure the investment is not wasted and that these special wheels look good for the life of the vehicle.
Special wheels are easily damaged and/or scratched. Occasionally check the rims for cracking, impact damage or air leaks. If any of these are found, replace the wheel. However, in order to prevent this type of damage and the costly replacement of a special wheel, observe the following precautions: