Consumer Tire Guide
Things you need to know about
auto and light truck tire care
TIRE INDUSTRY SAFETY COUNCIL
TIRE PLACARD AND SAFETY WARNING
Tires are designed and built with great care to provide thousands
of miles of excellent service. But for maximum benefit they must be
The most important factors in tire care are:
* Proper Inflation Pressure
* Proper Vehicle Loading
* Regular Inspection
* Good Driving Habits
Tire Inflation Pressure
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 or glove box door. If your vehicle doesn't
have a placard, check the owner's manual or consult with the vehicle or
tire manufacturer 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 manufacturers now mold a safety warning on the sidewall of
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.
Only specially trained persons should demount or mount tires. An
explosion of a tire and wheel assembly can result from improper or
careless mounting procedures.
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.
YOUR OWN TIRE PRESSURE GAUGE
Tire must be properly inflated. Determine tire inflation by using
an accurate tire pressure gauge. 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. Make sure it is calibrated up to 80 PSI. You
can order one by mail from the Tire Industry Safety Council. (See back
cover for details)
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
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.
When outdoor temperature changes occur, your tire's inflation
pressure is affected. For every 10 degree (Fahrenheit) drop in
temperature, tire pressure will drop one pound per square inch. In hot
weather, tires can lose up to two pounds of air per month.
Underinflation is the leading cause of tire failures so check inflation
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, where possible, are
equipped with valve caps to keep out dirt and moisture. Install a new
valve stem assembly 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 (See page 2.)
Proper Vehicle Loading
The tire placard shows the vehicle manufacturer's recommended cold
inflation pressure. You must not overload the 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
payload 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.
Load and inflation information for popular auto tire sizes may be
obtained from your local tire dealer, or tables may be obtained free by
sending a stamped, self-addressed business-size envelope to "Tables,"
Tire Industry Safety Council, Box 1801, Washington, D.C. 20013.
INSPECT YOUR TIRES REGULARLY
At least once a month inspect your tires closely for signs of
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 will be corrected at your tire dealer or
other service facility. If you catch 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 tread-wear 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 those wear bars, the tire is worn out and it's time to
As you inspect your tires, look for any stones, bits of glass,
metal or other foreign objects wedged in the tread, which 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's 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.
* Don't run over curbs or scuff the sidewall of a tire against the
curb when parking.
Avoid Tire Spinning
The centrifugal forces created by a rapidly spinning tire can cause
an explosion by literally tearing the tire apart. These forces act on
the complete tire structure, and can be of such magnitude as to break
beads as well as to rupture the entire carcass. Some vehicles are
capable of bringing a tire to its centrifugal force failing point in 3
to 5 seconds.
When stuck on ice, snow, mud or wet grass, the vehicle should be
rocked gently (alternately using forward and reverse gears) with the
least amount of wheel spinning. If that doesn't free the vehicle, get a
Never exceed 35 mph speed indicated on the speedometer. Never allow
anyone to stand near or directly ahead or behind the spinning tire.
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 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
After a tire has been severely impacted 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.
Consult your vehicle owner's manual and the tire sidewall for
instructions on proper use of a temporary spare.
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.
Improper mounting and overinflation may damage the tire or wheel
and can result in an explosion that could cause serious injury and
death. (See Safety Warning, Page 2).
Tire explosion can cause death, personal injury or property damage.
Excessive speed in a free-spinning tire can cause it to "explode"
from extreme centrifugal force.
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 smoothly to give you a comfortable ride and good tire
BALANCE: An unbalanced tire and wheel assembly may create an
annoying vibration when you drive on a smooth road and may result in
irregular tread wear.
ALIGNMENT: Misalignment in the front or rear, improperly operating
brakes or shock absorbers, bent wheels, sprung axle housings, worn
bushings, etc., cause uneven and rapid tread wear and should be
corrected by a qualified mechanic. Front wheel drive vehicles and those
with independent rear suspension require additional attention with
alignment of all four wheels.
All these systems should be checked periodically as specified by
the vehicle owner's manual or whenever you have an indication of
A bad jolt can throw your front end out of alignment even if you
had it checked an hour earlier. Such impact can also bend wheels,
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 or the tire
manufacturer for the appropriate pattern for your vehicle.
If your tires show uneven wear, ask the service person to check for
and correct any misalignment, imbalance or other mechanical problem
involved before rotation.
After rotation, adjust individual tire air pressure to the figures
recommended by the vehicle manufacturer for their new location--front or
rear--as shown on the tire placard in the vehicle. (See page 2.)
Sometimes front and rear tires on a vehicle use different pressures.
The purpose of regularly rotating tires is to achieve more uniform
wear for all tires on a vehicle. Before rotating tires, always refer to
individual owner's manuals for rotation recommendations for specific
vehicles. If no rotation period is specified, tires should be rotated
every 6000 miles or at any sign of uneven wear. The first rotation is
Do not include a "Temporary Use Only" spare tire in any rotation
patterns. If you have a matching full size tire as a spare and wish to
include it in the rotation process, insert the spare in the right rear
position and place the tire that would have gone on the right rear in
the trunk as the new spare.
THE SIDEWALL STORY
Your tire contains a lot of 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 (see page 2) and much other information.
On the sidewall of a popular "P-metric" speed-rated auto tire, "P"
stands for passenger; "205" represents the width of the tire in
millimeters; "60" 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, 90H in this example, consists of the load index and speed
A "B" in place of the "R" means the tire is a belted bias
construction. A "D" in place of the "R" means diagonal "bias"
The maximum load is shown in lbs. (pounds) and in kg. (kilograms),
and maximum pressure in PSI (pounds-per-square inch) and in kPa
(kilopascals). Kilograms and kilopascals are metric units of
The letters "DOT" certify compliance with all applicable safety
standards established by the U.S. Department of Transportation (DOT).
Adjacent to this is a tire identification or serial number. This serial
number is a code with up to eleven digits that are a combination of
numbers and letters.
The sidewall also shows the type of cord and number of plies in the
sidewall and under the tread.
The DOT requires tire manufacturers to grade passenger car tires
based on three performance factors: Treadwear, Traction, and Temperature
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.
However, it is erroneous 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: The 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 are A (the highest) B and C,
representing the tire's resistance to the generation of heat when tested
under controlled conditions on a specified indoor laboratory test wheel.
The typical information on the sidewall of a light truck tire:
LT -- stands for Light Truck. "LT235/85R16" is the size designation
for a metric light truck tire. "LOAD RANGE D" identifies the load and
RADIAL identifies that the tire has a radial construction. "MAX
LOAD SINGLE 2623 lbs. AT 65 psi COLD" indicates the maximum load rating
of the tire and corresponding minimum cold inflation pressure for that
load when used as a single. For normal operation, follow pressure
recommendations in owner's manual or on vehicle placard; "MAX LOAD DUAL
2381 lbs. AT 65 psi COLD" indicates the maximum load rating of the tire
and corresponding minimum cold inflation pressure when used in a dual
configuration. The other markings on the sidewall have the same meaning
as described for the passenger car tire.
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 (DOT code) are recorded and returned to the tire
manufacturer or his record-keeping designee. Tire registration enables
the manufacturer to notify you in the event of a recall.
When tires need to be replaced, don't guess what tire is right for
For the answer, first look at the tire placard. (See page 2.) 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 mount tires with the same size and
construction designations on the same axle.
It is preferred that all four tires be of the same size, speed
rating, and construction (radial or non-radial).
When two radial tires are used with two nonradials, 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 six speed symbols, "S, T, U, H, V,
or Z" 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 permissible
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
It is preferred that all tires be of the same size, construction
(radial, non-radial) and speed rating. Tires influence vehicle handling
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
COLD WEATHER DRIVING
Many parts of the U.S. have cold weather driving conditions at
least part of the year. Here are some things you should know about cold
Every time the outside temperature drops 10 degrees Fahrenheit, the
air pressure inside your tires goes down about one (1) pound per square
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 doesn't 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.
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
You can avoid this by equipping your vehicle with snow tires marked
with "MS," "MS," "M&S," "M + S," etc. on the sidewall.
If you change to snow tires, be sure they are the same size and
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
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 use of studs or ban them
altogether. Before applying 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
When you have a question about tires, or a problem, consult your
tire dealer. He is the best source of general information and
professional service on tires.
He has service manuals, wall charts and other industry publications
on tire load and inflation, tire repair and tire replacement. He can
provide you with the replacement tires your vehicle needs, balance your
tires and repair damaged tires which are repairable. Let him inspect
your tires periodically, and diagnose any problem you may have.
When you discover a tire is 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.
A PLUG BY ITSELF IS AN UNACCEPTABLE 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.
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 could 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
Such internal damage may not always be readily apparent and rapid
loss of air may still occur despite later installation of a proper
Save Gas With Proper Tire Inflation!
Check Your Tires At Least Once A Month--And Before Long Trips
Published in cooperation with:
* National Highway Traffic Safety Administration U.S. Department of
* American Automobile Association
* American Driver & Traffic Safety Education, Association
* American Petroleum institute
* Highway Users Federation
* National Safety Council
* National Tire Dealers and Retreaders Association
For more information, see the Tire Industry Safety Council web site