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Air Pressure
CHECK the pressure
in your tires at least monthly and before long trips when your tires are
cool (after the vehicle has been stopped 3 hours and then driven less
than one mile). Adjust to the vehicle manufacturers specified pressure
while tires are cold. Never bleed or reduce air pressure when tires are
hot. It is normal for pressure to build up as a result of driving. Use
an accurate tire gauge to check pressure and maintain it at the level
recommended by the vehicle manufacturer. Dont forget your standard size
or temporary spare tire. Your temporary spare - it requires a higher inflation
pressure. Remember: Under inflation is the most common cause of sudden
air loss or sudden failures in any kind of tire and may result in unexpected
loss of vehicle control or accidents.
Alignment
of Vehicle
A wheel alignment
adjustment may be necessary if the vehicle pulls to the right or the left
with the steering wheel is in straight ahead position. Another indicator
of the need for an alignment check is if tires are wearing unevenly.
All
Season Tires
All season tires can
be used throughout the year. The following markings appear on the sidewall
of the tire: M+S, M/S or M&S. This meets the RMA definition of a mud
and winter tire. However, there are also tires designed for severe snow
conditions. These tires will show a symbol of a mountain with a snowflake
next to the MS letters & are designed as winter tires.
Tires designed for
use in severe snow conditions generally have tread patterns, structure
and materials to give superior performance. These tires are marked with
the "M+S" designation plus a mountain/snowflake symbol. ABS
/ Anti-Lock Brake System
Under emergency braking
using conventional braking systems the wheels can lock up, making the
car un-steerable. ABS systems provide continuous monitoring and control
of the braking force and in some circumstances can reduce the braking
distance while maintaining full car steer ability.
Modern high-quality
tires are optimized and matched to the ABS functions. And "braking
on wet roads with ABS and ABS-brakes" are already often a standard
test required by auto manufactures for many tire test specifications.
ASR
/ Anti-slip-control
ASR is fitted to vehicles
to prevent wheels slipping, spinning on slippery or uneven surfaces.
Electronic sensors
are used to control and dose the power transmitted to the drive axle,
in order to ensure that tires can properly and reliably grip the road
during acceleration.
Aquaplaning
The contact area of
the tire to the road is reduced when water is on the road. In extreme
cases, the vehicle "hydroplanes (glides) on the water". This
will drastically reduce the control of the vehicle.
Tires have special
tread patterns that ensure optimum drainage of the water away from the
tread surface. This effect does however reduce proportionally as speed
increases.
The most effective
protection is to adjust driving speeds to the weather conditions.
Balancing
At high speeds, tires
generate enormous centrifugal forces. Even tiny irregularities in the
tire of only a few grams are multiplied by many orders of size.
Such imbalance stresses
tires and suspension. This weight irregularity can be tested and identified
at in tire dealerships and is balanced by adding small counter-weights.
Every time a tire
is fitted to a wheel, it should be balanced.
Bead
The bead of the tire
is that part which sits on the rim. At the center of the bead is the core,
which comprises a bundle of steel wires embedded in rubber.
This provides a safe
and solid seating of the tire on the rim.
Braking
distance
The distance required
for braking depends on the speed of the vehicle, the condition of the
road surface and the condition of the tires, in particular the tread.
Check the tires tread depth regularly and change your tires when worn
down to the "tread wear indicators" located at the bottom of
the tread grooves.
Camber
The purpose of wheel
camber is to reduce friction during cornering. The camber is measured
when the wheels are standing on a flat surface. The difference from the
vertical (inward or outward tilt of the tire) is then referred to as either
positive or negative camber.
Casing
Modern tires are made
of many different materials and components.
Looked at schematically,
there is the outer cover - the tread and sidewall, and the substructure,
the casing.
Casing components
may include steel and/or textile cord plies, the inner liner (to make
tube-less tires airtight), sidewalls, the apexes, the bead core (keeps
the tire on the rim) and the bead reinforcement.
Chains
Even modern winter
tires can sometimes not help when there are huge amounts of snow and steep
gradients. In these situations traction, lateral control and reliable
braking require tire chains. In order to be prepared it is recommended
to try and fit chains in a "dry run".
Snow chains have to
be draped over the drive wheels.
Please also note that
a maximum speed is given. With some low profile tires a problem can result:
the reduced space between the tires and the wheel arch leaves no room
to fit snow chains.
Date
of Manufacture
The date of manufacture
of a tire is indicated on the tire's sidewall at the end of the DOT serial
number.
Tire manufacturers
have adopted a standard identification system: four numbers, which indicate
the week and the year of manufacture. For example, the figures 0201 indicate
that the tire was made in the second week of the year 2001.
Direction
of Rotation
On standard tires
with symmetrical tread patterns, it does not matter which way the tire
is fitted on the rim and in which position it is fitted on the car.
Some tire manufacturers
have, however, started producing tires with specific directions of rotation
in order to improve wet grip and optimize noise generation.
The direction of rotation
is marked on the side of the tire with an arrow. This side of the tire
must be on the outside, and the tire must roll forwards in the direction
of the arrow for optimum tire performance.
A number of tires
with asymmetric tread patterns are also now available which do not have
a specific direction of rotation.
DOT
Serial Number
The "DOT"
symbol certifies the tire manufacture's compliance with the U.S. Department
of Transportation tire safety standards. The DOT serial number is located
on the lower sidewall of the tire, on one side only. Below is a description
of the serial number. Starting in the year 2000, four numbers are used
for the Date of Manufacture, first two numbers identify the week and the
last two numbers identify the year of manufacture. Prior to year 2000
three numbers are used for the Date of Manufacture, first two numbers
identify the week and the last number identifies the year of manufacture.
To identify tires manufactured in the 90's a decade symbol (a triangle
on its side) is located at the end of the DOT serial number.
For Example: DOT
NJ HR 2AE2 529
529
Date of Manufacturer,
example: 529 (52nd week of 1999) or 5200 (52nd week of 2000).
2AE2
Tire Type Code (coding
for type of tire optional by manufacture).
HR
Tire Size Code Number.
NJ
Manufactures Plant
Identification Code
DOT
Reference Symbol (certifies
the tire manufactures compliance with U.S. Department of Transportation
tire safety standards).
ESP
/ Electronic Stability Program
An Electronic Stability
Program, ESP, helps master critical driving situations, for example when
the vehicle suddenly over steers during cornering or when sudden evasive
action is required. The systems detects skidding movements within fractions
of a second and can take corrective action.
ESP systems not only
function when road conditions are good, but also on wet, on icy and on
unpaved roads.
Technically speaking,
The ESP system combines the ABS / Anti-Lock Brake Block System, electronic
braking pressure distribution, ASR / Anti-slip-control and yaw control.
Emergency
Mobility Systems
If a tire punctures
and looses air, a standard size or a temporary special spare tire must
be put on in order to continue the journey.
In order to avoid
the troublesome, sometimes dangerous procedure of changing a tire on an
open road, various manufacturers now offer so-called emergency mobility
systems.
What these tires have
in common is that when all air pressure is lost the rim does not destroy
the tire. The journey can be continued without changing the tire - over
a limited distance at a restricted speed.
Load
Index, Ply Rating or Load Range
These symbols are
found on the sidewall of the tire indicating the load - carrying capacity
of the tire.
Mixing
Tires
It is recommended
that all four tires be of the same size, construction and speed rating.
If tires of different speed rating are mounted on a vehicle, the vehicle
speed capability will be limited to the lowest speed-rated tire on the
vehicle. It is recommended that the lower speed-rated tires be placed
on the front axle regardless which axel is driven. This should be done
to prevent a potential oversteer condition. Vehicle handling may also
be affected. Consult the tire manufacture.
Radial
Tires
Radial tires have
body cords that run across the tire nearly perpendicular to the beads.
Radial tires have belt plies, which are laid diagonally under the tread
to stabilize and strengthen the tread area. and add flexibility to the
sidewall. By restricting tread movement during contact with the road,
the belt plies increase improve tread life, traction and improve handling.
Reinforced
or XL (extra load) Tires
Reinforced or XL (extra
load) tires are specially reinforced tires. They can carry higher loads
than a tire of the same size.
Reinforced tires are
designated on the Sidewall by the letters "RF", extra load tires
with the letters "XL"
Reinforced and XL
tires require need higher inflation pressures compared to standard tires.
Revolutions
Per Mile (RPM)
The number of revolutions
a tire makes in one mile, at a given load, speed and inflation. Sometimes
called RPK or revolutions per kilometer.
Rolling
Resistance
The drag force required
to put a free rolling tire into motion. Tires are not rigid, but flexible.
During driving the tires compress, and flex.
This flexing absorbs
energy, converting it into heat.
In order to reduce
rolling resistance, manufacturers use special rubber compounds. Any reduction
in the rolling resistance of the tire helps reduce fuel consumption.
Since rolling resistance
also increases with low Inflation pressure, it is beneficial to check
the pressure of tires regularly.
Rotation
Refer to your Vehicle
Owners Manual for recommended rotation pattern and interval for your vehicle.
If not available, follow one of the patterns shown below. It is recommended
to rotate your tires every 6,000 to 8,000 miles, or sooner if uneven treadwear
begins to appear. The purpose for regular rotation is to achieve more
uniform treadwear on all tires on your vehicle. If tires show uneven treadwear,
ask the serviceperson to check and/or correct any alignment or other mechanical
problem before rotation.
This is true for both
front wheel and rear wheel drive vehicles. Full size spare spare tires
should be included in the rotation pattern for your vehicle. Compact spares
(temporary use spares) should not be included in the rotation pattern.
Speed
Symbol
Speed ratings for
tires are identified by means of a speed symbol shown on the sidewall
of a tire. The maximum speed for these symbols in shown in the table.
Although a tire may be speed rated, tire manufactures do not endorse the
operation of any vehicle in an unsafe or unlawful manner. Furthermore,
tire speed ratings do not imply that a vehicle 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.
Speed ratings are
based on laboratory tests which relate to performance in the road, but
are not applicable if tires are underinflated, overloaded, worn out, damaged
or altered.
Example: Tire
size P215/60R15 H 185/65 R 15 H: the H indicates a maximum permitted speed
of 130 MPH.
Temporary
Spare Tires
Temporary spares are
designed to carry the same load as the standard size tire on your vehicle
and can be applied to any position. Maintain the proper inflation pressure
as shown on the sidewall of the tire, it requires a higher inflation pressure
than a standard size tire. Refer to the information on the sidewall of
the tire for proper usage & speed restrictions. With such a tire, a vehicle may be operated
until it is convenient to repair or replace the disabled tire. Have your
standard tire repaired or replaced as soon as possible, then return the
temporary spare to the trunk to conserve its useable tread life. The temporary
tire can be worn down to the tread wear indicators, same as your standard
tire. At such time the tire must be replaced.
Toe
The toe describes
the distance between the centerlines of the tires on an axle. The toe
setting can be adjusted on all cars.
Since most wheels
tend to run towards the outside because of the camber, most cars are set
with a slight positive toe-in. This means that the wheels are slightly
closer together at the front than at the back.
Incorrect settings
for your vehicle result in uneven tire wear. If you notice uneven tire
wear, then have your vehicle alignment settings checked.
Tread
The tread is that
part of the tire with the groove pattern which is in contact with the
road. The tread is specifically design to provide traction for stopping,
starting, cornering and provide long lasting wear.
Tread
Depth
The measured distance
from the tread surface to the bottom of the main grooves away from the
Tread Wear Indicators. Usually specified in 1/32 of an inch.
TWI
(tread wear indicator)
Tread wear indicators
("wear bars") are located at the base of the main grooves and
are equally spaced around the tire. Always remove tires from service when
they reach a remaining tread depth of two thirty-seconds of an inch (2/32").
If not corrected, wet weather accidents are more likely to happen due
to skidding on bald or nearly bald tires. Also, excessively worn tires
are more susceptible to damage from road hazards. 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
the tire.
Tire
Size Designation
The dimensions of
a tire are detailed on the sidewall.
In the case of a P185/65R
14 tire, the figures mean the following: 185 = width of tire in mm; 65
= the ratio of the height to the width as a percentage; R = radial construction;
14 = diameter of the rim in inches.
Tire
Storage
Tires should be stored
in a dry, cool place, away from sunlight and sources of ozone, such as
electric motors.
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 or over black asphalt or other
heat-absorbent or reflective surfaces, such as snow-covered ground or
sand. Solvents, fuels, lubricants and chemicals should be kept out of
contact with tires.
Spare tire carriers
on your vehicle are not intended to be used for long term tire storage.
If your vehicle has a full size tire (same size and type tire recommended
for use by the vehicle manufacture not temporary use spares) as a spare,
it should be included in the tire rotation pattern.
UTQG
(Uniform Tire Quality Grading)
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 AA, 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.
Valve
The valve, fitted
in the wheel, ensures that the tire can be filled with air. The correct
valve is required for the correct wheel/tire assembly, this is the job
of the tire dealer. The cause of a slow loss of air pressure can be a
defective valve. The valve cap should always be fitted to the valve in
order to protect the valve core from dirt and moisture.
Valve
Cap
The valve cap, although
small, has a very important job: it protects the sensitive valve internals
from dust, dirt and humidity. If valve caps are lost they should be replaced
immediately in order to avoid expensive damage later.
Winter
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 winter tires on their vehicles.
You can avoid this
by equipping your vehicle with winter tires marked with "MS,"
"M&S," or "M + S" on the sidewall and severe snow marking.
If you change to winter
tires, be sure they are the same size and construction type as the other
tires on the vehicle.
It is recommended that winter tires be applied on all four positions.
It is acceptable to install winter tires only on the rear position of a rear wheel drive vehicle.
If winter tires are installed on the front position of any vehicle, the MUST also be installed on the rear position. Without winter tires on the rear, vehicle handling can be adversely affected. This may result in loss of vehicle control which could cause serious injury or death.
If winter tires with a lower speed rating than listed on the vehicle placard are installed for use in winter conditions, the speed capability of the vehicle is reduced to the speed rating of the winter tires.
In areas where heavy
snowfalls are frequent, many drivers carry chains for use in emergencies,
or have their tire dealer apply studded winter tires or install tires for
use in severe snow conditions.
Most states have time
limits on the use of studs. Before installing studded tires, check the
regulations in your area. If studded tires are applied to the front axle,
they also must be applied to the rear axle.
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.
Tires designed for
use in severe snow conditions generally have tread patterns, structure
and materials to give superior performance. These tires are marked with
the "M+S" designation plus a mountain/snowflake symbol. |