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
- Regular Inspection
- Good Driving Habits
- Vehicle Conditions
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.
WARNING
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.
Inflation Tips
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.
Underinflation
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.
Highway Hazards
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.
Spare Care
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.
Aerosol Inflators
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.
Balance
An unbalanced wheel and tire assembly may create an annoying vibration
when you drive on a smooth road and may result in irregular treadwear.
Alignment
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.
Tire Rotation
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.
Passenger Tires
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).
Treadwear
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
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.
Temperature
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.
Speed Ratings
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.
COLD-WEATHER DRIVING
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.
Snow Tires
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 rear axle or on all four wheel positions.
If purchasing 2 new tires it is recommended that you install them on the
back of the car. If you install a high traction tire on the front drive
axle, you are leaving the lighter end of the vehicle (the rear) with no
traction improvement. Most tire manufacturers recommend that front wheel
drive vehicles have all four tires of equal traction. In all cases, install
new tires on the rear axle. If your front tires lose grip first, your
vehicle will tend to lose control by going straight, even in a turn. This is
understeer, which can be controlled by slowing down and steering in the
direction of the turn...this will allow your car to come back into line.
But if the rear tires lose grip first, your vehicle, could spin, which is
oversteer and more difficult to control, this requires you to make quick,
precise steering corrections in the opposite direction of the turn, not a
natural reaction. It is easier to control understeer than oversteer.
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.
SERVICE ASSISTANCE
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.
STORAGE TIPS
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.
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Most people are now aware that indoor air pollution is an issue of
growing concern and increased visibility.