Things You Need to Know About Automobile Tire Care and Safety|
Things You Need to Know About Automobile Tire Care and Safety
Tires are designed and built with great care to provide thousands of miles of excellent service. But for maximum benefit, they must be maintained properly.
The most important factors in tire care are:
Proper Inflation Pressure
Proper Vehicle Loading
Good Driving Habits
The Benefits of Proper Inflation
With the right amount of air pressure, your tires wear longer, save fuel and help prevent accidents. The "right amount" of air is the pressure specified by the vehicle manufacturer for the front and rear tires on your particular model car or light truck. The correct air pressure is shown on the tire placard (or sticker) attached to the vehicle door edge, door post, glove box door or fuel door. If your vehicle doesn't have a placard, check the owner's manual or consult with the vehicle manufacturer, tire manufacturer or your local tire dealer for the proper inflation.
The tire placard tells you the maximum vehicle load, the cold tire pressures and the tire size recommended by the vehicle manufacturer.
If you don't take proper care of your tires, the results can be serious. Most tire companies are either supplying a handbook or are molding a safety warning right onto the tire sidewall. A typical warning is shown.
Serious injury may result from tire failure due to underinflation / overloading. Follow owner's manual or tire placard in vehicle. Explosion of tire/rim assembly. Only specially trained persons should mount tires.
As you see, it points out that serious injury may result from tire failure due to underinflation or overloading. Motorists are strongly advised to follow the vehicle owner's manual or the tire placard in the vehicle for proper inflation and loading.
Never try to mount your own tires. Only specially trained persons should mount or demount tires. An explosion of a tire and wheel assembly can result from improper or careless mounting procedures.
If you do mount your own tires, make sure you have the right equipment, the right training and the right information before proceeding. Always use a restraining device when mounting a tire on a rim, and be sure to stay back from the tire when inflating it. Make sure to follow the inflation instructions.
Always replace a tire with another tire of exactly the same bead diameter designation and suffix letters. For example: A 16" tire goes on a 16" rim. Never mount a 16" tire on a 16.5" rim. A 16.5" tire goes on a 16.5" rim. Never mount a 16.5" tire on a 16" rim.
While it is possible to pass a 16" diameter tire over the lip or flanges of a 16.5" size diameter rim, it cannot be inflated enough to position itself against the rim flange. If an attempt is made to seat the tire bead by inflating, the tire bead will break with explosive force and could cause serious injury or death.
Remember, mounting and demounting tires and wheels should be left to skilled professionals who are aware of the safety hazards involved and who have the proper tools and equipment to do the job safely.
Your Own Tire Pressure Gauge
Tires must be properly inflated. Use an accurate tire pressure gauge to determine your tire pressure. You can't tell when tires are "low," or underinflated, just by looking. Air meters at service stations may be inaccurate due to exposure or abuse. You should have your own personal tire gauge to be sure. Purchase an accurate tire gauge from your tire dealer, auto supply store or other retailer.
Check tire inflation pressure (including the spare) at least once a month and before every long trip. Tires must be checked when they are cold; that is, before they have been run a mile. If you must drive over one mile for air, before you leave home, measure the cold inflation pressure of each tire and record the actual underinflation amount for each tire.
Upon arriving at the service station, measure each tire's inflation again and then inflate the warm tire to a level that is equal to this warm pressure, plus the cold underinflation amount.
Tires lose air normally through the process of permeation. Changes in outdoor temperature can affect the rate at which your tire loses air. This change is more pronounced in hot weather. Generally speaking, a tire will lose one or two pounds of air per month in cool weather, and even more in warmer weather. Underinflation is the leading cause of tire failure, so check inflation pressure regularly.
Never "bleed" or reduce air pressure when tires are hot. It is normal for pressures to build up as a result of driving.
Make sure all tire valves and extensions are equipped with valve caps with rubber gaskets to keep out dirt and moisture. Have a new valve stem assembly installed whenever a tire is replaced. Underinflation or overloading creates excessive heat, and can lead to tire failure, which could result in vehicle damage and/or serious injury or death. Proper inflation extends tire life and saves fuel. Maintain the inflation pressure listed in the vehicle owner's manual or on the tire placard.
Proper Vehicle Loading
In addition to showing the vehicle manufacturer's recommended cold inflation pressure, the tire placard also shows the maximum load of the vehicle. Do not overload your vehicle. Remember, baggage carried on top of any vehicle counts as additional load.
If you are towing a trailer, remember that some of the weight of the loaded trailer transfers to the towing vehicle. That reduces the load which can safely be placed in the towing vehicle. The only sure way to prevent overload is to weigh, axle by axle, the fully loaded vehicle on reliable platform scales.
Inspect Your Tires Regularly
At least once a month, inspect your tires closely for signs of uneven wear.
Uneven wear patterns may be caused by improper inflation pressures, misalignment, improper balance or suspension neglect. If not corrected, further tire damage will occur.
Most likely, the cause can be corrected at your tire dealer or other service facility. If you find a problem and correct it in time, your tires may be able to continue in service.
Certain uneven wear patterns may indicate that the tire has suffered internal structural damage and requires the immediate attention of your tire dealer.
When the tread is worn down to one-sixteenth of an inch, tires must be replaced. Built-in treadwear indicators, or "wear bars", which look like narrow strips of smooth rubber across the tread, will appear on the tire when that point of wear is reached. When you see these wear bars, the tire is worn out and it's time to replace it.
Inspect your tires frequently. Look for any stones, bits of glass, metal or other foreign objects wedged in the tread. These may work deeper into the tire and cause air loss.
If any tire continually needs more air, have it taken off the vehicle and checked to find out why it is leaking. Damage to the tire, wheel or valve may be the problem.
Good Driving Habits
The way you drive has a great deal to do with your tire mileage and safety. So cultivate good driving habits for your own benefit.
Observe posted speed limits.
Avoid fast starts, stops and turns.
Avoid potholes and objects on the road.
Do not run over curbs or hit the tire against the curb when parking.
When You're Stuck
The forces created by a rapidly spinning tire can cause an explosion by literally tearing the tire apart. These forces impact the whole tire structure and can rupture the entire casing. Some vehicles are capable of bringing a tire to this failing point in 3 to 5 seconds.
When stuck on ice, snow, mud or wet grass, the vehicle should be rocked gently back and forth by repeatedly shifting the gear lever from drive to reverse on automatic transmissions, or reverse to second on manual transmissions. This should be done with the least amount of wheel spinning. If that doesn't free the vehicle, get a tow.
No matter how carefully you drive, there is always a possibility that you may eventually have a puncture and wind up with a flat on the highway. Drive slowly to the closest safe area out of traffic. This may further damage the flat tire, but your safety is more important.
Follow the vehicle manufacturer's instructions for jacking up the vehicle, taking off the wheel and putting on the spare. Then drive to a place where the flat tire can be inspected for possible repair or replacement.
After a tire has received a severe impact, such as hitting a curb or pothole, you must have it removed from the wheel and inspected both inside and out for impact damage.
An impact-damaged tire may appear serviceable on the outside, but can fail later after the road hazard injury.
Many late-model vehicles are equipped with temporary spare tires and wheels which are different from your regular tires and wheels. Some may require higher inflation pressure, or the use of special canisters to inflate the tire.
You may operate a vehicle with such a tire within the limits indicated on the tire's sidewall, until it is convenient to repair the disabled tire or replace it with one of the same size designation and construction as the other tires on the vehicle.
Always check the inflation in your spare tire every time you check all the others. A spare tire with no air in it is no help to you in an emergency. If you have an inflatable spare, be sure to check the aerosol air inflation pressure canister to be sure it has not been damaged. If so, have it checked by an expert.
Remember, improper mounting and overinflation may damage the tire or wheel and can result in an explosion that could cause serious injury and death.
Do not depend on tire aerosol sealants and inflators to fix a damaged tire permanently. These products are designed to provide only a temporary, emergency repair to help get you off the road and to the nearest tire repair facility.
Some aerosol products of this type use flammable gases, such as butane, propane or isobutane, as propellants. Follow all directions and precautions printed on the canister when using these products. Be sure to inform tire service personnel that you have used a flammable aerosol to inflate your tire.
Vehicle Conditions Affecting Tires
There is a close working relationship between your tires and several mechanical systems in your vehicle. Tires, wheels, brakes, shock absorbers, drive train, steering and suspension systems must all function together to give you a comfortable ride and good tire mileage.
An unbalanced wheel and tire assembly may create an annoying vibration when you drive on a smooth road and may result in irregular treadwear.
Misalignment of wheels in the front or rear, improperly operating brakes or shock absorbers, bent wheels, worn bushings and other mechanical problems cause uneven and rapid treadwear and should be corrected by a qualified mechanic. Front-wheel-drive vehicles, and those with independent rear suspension, require special attention with alignment of all four wheels.
These systems should be checked periodically as specified by the vehicle owner's manual or whenever you have an indication of trouble.
A bad jolt, such as hitting a pothole, can throw your front end out of alignment even if you had it checked an hour earlier. Such an impact can also bend the rim, causing a loss of air pressure, and damage your tires with little or no visible external indication.
Sometimes irregular tire wear can be corrected by rotating your tires. Consult your car owner's manual, the tire manufacturer or your tire dealer for the appropriate pattern for your vehicle.
If your tires show uneven wear, ask your tire dealer to check for and correct any misalignment, imbalance or other mechanical problem involved before rotation.
Sometimes front and rear tires on a vehicle use different pressures. After rotation, adjust individual tire air pressure to the figures recommended by the vehicle manufacturer for the new locations -- front or rear -- as shown on the tire placard in the vehicle.
The purpose of regularly rotating tires is to achieve more uniform wear for all tires on a vehicle. Before rotating your tires, always refer to your individual owner's manual for rotation recommendations. If no rotation period is specified, tires should be rotated approximately every 6,000 miles.
However, rotate your tires earlier if signs of irregular or uneven tire wear arise, and have the vehicle checked by a qualified technician to determine the cause of the wear problem. The first rotation is most important.
The Sidewall Story
Your tire contains very useful information molded into the sidewall. It shows the name of the tire, its size, whether it is tubeless or tube type, the maximum load and maximum inflation, the important safety warning and much other information.
Here is information about the sidewall of a popular "P-metric," speed-rated auto tire. "P" stands for passenger, "215" represents the width of the tire in millimeters; "65" is the ratio of height to width; "H" is the speed rating; "R" means radial; and "15" is the diameter of the wheel in inches. Some speed-rated tires carry a Service Description, instead of showing the speed symbol in the size designation. The Service Description, 89H in this example, consists of the load index (89) and speed symbol (H).
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track.
A tire graded 200 would wear twice as long on the government test course under specified test conditions as one graded 100.
It is wrong to link treadwear grades with your projected tire mileage. The relative performance of tires depends upon the actual conditions of their use and may vary due to driving habits, service practices, differences in road characteristics and climate.
Traction grades, from highest to lowest, are A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete.
The temperature grades, from highest to lowest, are A, B and C. These represent the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel.
Replacement Tire Selection
IMPORTANT: Always check the vehicle manufacturer's recommendation before replacing a tire with a different size and/or construction.
When buying new tires, be sure your name, address and tire identification number are recorded and returned to the tire manufacturer or its record-keeping designee. Tire registration will ensure that you will be notified promptly in the event the tire manufacturer needs to contact you.
When tires need to be replaced, don't guess what tire is right for your vehicle.
For the answer, first look at the tire placard. As you will see, that placard tells you the size of the tires which were on the vehicle as original equipment.
Tires should always be replaced with the same size designation, or approved options, as recommended by the automobile or tire manufacturer. Never choose a smaller size, with less load-carrying capacity than the size on the tire placard. Always have tires mounted with the same size and construction designations on the same axle. It is recommended that all four tires be of the same size, speed rating and construction (radial or non-radial). However, in some cases, the vehicle manufacturer may require different-sized tires for the front and rear axles. When two radial tires are used with two non-radials, put the radials on the rear axle.
Some tires are now marked with letters to indicate their speed rating, based on laboratory tests which relate to performance on the road. Tires may be marked with one of eight speed symbols, M, S, T, U, H, V, Z or W, to identify the particular tire's speed rating.
When replacement of tires is required, consult the vehicle manual for proper size and speed rating (if required).
If the vehicle manual specifies speed-rated tires, the replacement tires must have the same or higher speed rating to maintain vehicle speed capability.
If tires with different speed ratings are mounted on the same vehicle, the tire or tires with the lowest rating will limit the tire-related vehicle speed.
Tire speed ratings do not imply that vehicles can be safely driven at the maximum speed for which the tire is rated, particularly under adverse road and weather conditions, or if the vehicle has unusual characteristics. Never operate a vehicle in an unsafe or unlawful manner.
Types of Tire Construction
Tires should be of the same size, construction (radial, non- radial) and speed rating, unless specified otherwise by the vehicle manufacturer. Tires influence vehicle handling and stability.
Match tire size designations in pairs on an axle (or four tires in dual application), except for use of a temporary spare tire.
If radial and non-radial tires are used on a vehicle, put radials on the rear. If radial and non-radial tires are used on a vehicle equipped with dual rear tires, the radials may be used on either axle. Never mix radial and non-radial on the same axle except for use of a temporary spare tire.
Snow tires should be applied in pairs (or as duals) to the drive axle (whether front or rear) or to all positions. Never put non-radial snow tires on the rear if radials are on the front, except when the vehicle has duals on the rear. If studded tires are used on the front axle, they must also be used on the rear axle.
Match all tire sizes and constructions on four-wheel-drive vehicles.
Here are some things you should know about cold-weather driving.
How Cold Temperature Affects Tires
Every time the outside temperature drops 10 degrees Fahrenheit, the air pressure inside your tires goes down about one or two pounds per square inch.
You should check your tire pressures frequently during cold weather and add the necessary air to keep them at recommended levels of inflation at all times.
Never reduce tire pressures in an attempt to increase traction on snow or ice. It does not work and your tires will be so seriously underinflated that driving will damage them.
If one of the drive wheels becomes stuck, the centrifugal forces created by a rapidly spinning tire can cause an explosion by literally tearing the tire apart. Never exceed the 35 mph indicated speedometer speed or stand near the spinning tire.
If your vehicle is stuck and a tow truck is not readily available, gently rock your vehicle back and forth, repeatedly shifting the gear lever from drive to reverse on automatic transmissions, or reverse to second on manual transmissions, while applying gentle pressure to the accelerator. Caution: If you have an anti-lock braking system (ABS) in your car, follow the operational instructions in your owner's manual.
In snowy areas, many cities and counties have "snow emergency" regulations which are invoked during heavy snowfalls. Check with authorities for the rules in your area. Under some rules, motorists are subject to fines if they block traffic and do not have snow tires on their vehicles.
You can avoid this by equipping your vehicle with snow tires marked with "MS," "M&S," and "M+S" on the sidewall. The letters "M" and "S" stand for mud and snow.
If you change to snow tires, be sure they are the same size construction type as the other tires on the vehicle.
Snow tires should be used in pairs (or as duals) on the drive axle (whether front or rear) or on all four wheel positions. Never put non-radial snow tires on the rear if radials are on the front, except when the vehicle has duals on the rear. In areas where heavy snowfalls are frequent, many drivers carry chains for use in emergencies, or have their tire dealer apply studded snow tires. When studded snow tires are mounted on the front axle, studded tires also must be placed on the rear axle. Most states have time limits on the use of studs or ban them altogether. Before installing studded tires, check the regulations in your area. If you use chains, make sure they are the proper size and type for your tires, otherwise they may damage the tire sidewall and cause tire failure.
When you have a question about tires, or a problem, consult your tire dealer. The dealer is the best source of general information and professional service on tires.
Your dealer has service manuals, wall charts and other industry publications on tire load and inflation, tire repair and tire replacement. Your dealer can provide you with the replacement tires your vehicle needs, balance your tires and repair damaged tires which are repairable. Let the dealer inspect your tires periodically and diagnose any problem you may have.
Loss of Tire Pressure
When you discover a tire losing air, it must be removed from the wheel by an expert for complete internal inspection to be sure it is not damaged. Tires run even short distances while severely underinflated may be damaged beyond repair.
Punctures up to 1/4 inch, when confined to the tread, may be repaired by trained personnel. These tires must be removed from the wheel, inspected and repaired, using industry-approved methods which call for an inside repair unit and a plug.
Plugs vs. Patches
A PLUG BY ITSELF IS AN UNACCEPTABLE REPAIR. The repair material used - for example, a "combination patch and plug" repair - must seal the inner liner and fill the injury to be considered a permanent repair. Never use a tube in a tubeless tire as a substitute for a proper repair.
Individual tire manufacturers may differ on whether the speed category applies to speed-rated tires that have been repaired. Consult the tire manufacturer for recommendations.
Serviceable Tire Injuries
Injuries larger than 1/4 inch must be referred to a full-service repair facility. No repairs to the sidewall of a tire should be made without consulting the tire manufacturer. After a tire has been repaired, check for leaks or other damage not detected at the time of repair. Improper repairs can cause sudden tire failure.
Air loss due to punctures can ruin tires that might have been saved had they been removed in time for proper repair. Gradual air loss raises a tire's operating temperature. This can cause some of the components to separate, or damage the tire body in ways that create rapid or sudden air loss.
Such internal damage may not always be readily apparent, and rapid loss of air may still occur despite later installation of a proper repair.
Tires should be stored upright and in a dry, cool place, away from sunlight and sources of ozone, such as electric motors.
However, if you must store tires flat (one on top of the other), make sure you don't stack too many on top of each other. Too much weight can damage the bottom tire.
Also be sure to allow air to circulate around all sides of the tires, including underneath, to prevent moisture damage.
If storing tires outdoors, protect them with an opaque waterproof covering and elevate them from the ground. Do not store tires on black asphalt, other heat-absorbent surfaces, snow-covered ground or sand.