Tires are simply the wearable and therefore replaceable part of the
tire/wheel assembly. Although many different types of tire designs have been
used since the dawn of the automobile, the radial tire has virtually replaced
all other varieties. Radial tires, by far, deliver better safety and handling,
fuel economy, steering, traction and cornering. The typical radial tire
consists of a bead, a casing, belts, and tread.
Today, nearly all tires have belts made from steel. Radial
tires also last much longer than any previous tire design. Although driving
habits and tire care play a key role in tire life, radial tires may last as
long as 80,000 miles. Virtually all of today’s tires used on automobiles,
and many used on light trucks, have a tubeless design. This means there is not
a separate balloon-like tube inside the tire, as was the case with older tire
Tires serve as the wearable part of the overall tire/wheel assembly, but they
also play a large role in vehicle safety. Today’s tires must provide good
traction under a wide range of driving and road conditions while providing long
Tips/Suggestions: Check tire pressure frequently and also inspect the tires
for abnormal tread wear and cuts and bruises along the sidewall. Rotate and
balance the tires on a regular basis. If your car has a flat, have the tire
professionally repaired. The best way to repair a tire is to have it removed
from the rim, the inside inspected and corrective measures taken. When replacing tires, install only tires of
the size recommended for your vehicle. Installing the wrong tires can result in
contact with body panels or steering and suspension parts. The wrong tires can
also affect speedometer readings and engine/transmission control.
Wheels can be made of steel, aluminum or various alloys. Steel wheels often
have a wheel cover affixed to the outer edge for appearance.
Wheels support the tire and must be able to withstand loads from acceleration,
braking and cornering. Aluminum and alloy wheels also serve an aesthetic
purpose and dress up the vehicle’s appearance.
Tips/Suggestions: Wheels should be
cleaned frequently using a suitable wheel cleaner. Use extreme care not to use
any abrasive pads or cleaners that may remove the protective coating and
scratch the wheels. It is best to clean the wheels while they’re cool. Clean
one at a time and rinse all cleaner away. Wheel cleaner should not be allowed
to sit on wheels for extended periods.
Tires have a coding system all their own that indicates key things like
size, application, speed rating, treadwear factors and some others. All of this
information is represented through an ordered series of numbers and letters on
the sidewalls of tires.
Purpose: Tires are a normal wear item and eventually
you’ll be faced with replacing them. When you do, making the right choices can
make a big difference in your satisfaction once your new tires are installed.
Tips/Suggestions: With a P225/75R15 tire as an example, “P”
represents passenger car applications (LT=Light Truck), 225 indicates the width
of the tread in millimetres, 75 represents the aspect ratio (width of the
tread, divided by sidewall height), “R” means radial construction
(most tires nowadays) and the 15 means the diameter of the wheel in inches. A
tire may also carry a speed rating, which represents the maximum safe driving
speed for a given tire. If this is the case, the rating will precede the
“R”. Speed ratings range from “S” to “Y”, which
represent 112 and 186 miles per hour respectively. (Speed-rated tires are
usually used in high-performance applications.)
In most cases, cars and minivans are originally equipped
with passenger car tires, whereas larger vehicles like pickups, SUVs and the
like come equipped with light-truck tires. It’s important to stick with the
size tires and types as recommended by your car’s manufacturer or in a tire
application guide from a tire maker. Using tires of the wrong size can
interfere with steering and suspension parts and it can affect the accuracy of
your car’s speedometer along with onboard control technology such as the
transmission and anti-lock brakes.
There are three
other factors that may be helpful in your tire selection process. These three
“T’s” are treadwear, traction and temperature. As with tire sizes,
the codes for these are marked on the sidewall of the tire, too. The treadwear
number is a relative indicator of just that — the higher the number, the
better. In theory, a treadwear index of 200 means that the tire will last twice
as long as a tire with a 100 index.
Next, comes the
traction index, which is expressed as a letter. A tire that performs well
during braking on both wet concrete and asphalt gets an “A” index; a
tire that performs well on only one of the surfaces gets a “B” index;
and a tire that performs poorly on both surfaces gets a “C” index.
The last of the
“T’s” is temperature resistance. An “A” index means the
tire has a high resistance to temperature; “B” means a medium
temperature-resistance and a “C” index indicates that the tire meets
basic safety standards.
There are still
other considerations that go into formulating a tire choice that’s just right
for your car, based on personal preferences. This may include the type of tread
for on- or off-road use, the amount of noise the tires produce when driving on
paved surfaces and other appearance-related options like raised white letters
or black sidewalls.
Checking Tire Tread
There are several simple ways to check tire tread depth. The first way is to
measure tread depth with a tread depth gauge.
Tire wear bars are also used on today’s tires as a hands-off visual
indication that a tire needs replacement.
Regular tread depth checks are important to ensure that your car’s tires are
safe. Excessive wear can result in a loss of traction, especially on wet and
slippery roads. Tires are regular wear items and staying on top of their
condition not only ensures your safety, but also gives you the opportunity to
plan ahead and budget for inevitable tire replacement.
Maintenance Tips/Suggestions: When using a tread
depth gauge, tires need to have at least 1/16-in. of tread or more (this is the
minimum amount of tread allowed by law).
If a wear bar across the width of
the tire is flush with the tread surface, it is time to replace the tire.
is best to replace tires in sets of four. If your car’s tires show signs of
abnormal or unequal wear, have this looked into by a professional technician.
Excessive wear on both outer edges generally indicates under-inflation.
Excessive wear in the centre of the tread generally indicates over-inflation.
Cupping or dipping of certain tread sections may indicate worn suspension parts
or a wheel balance problem. Saw-toothed or feathered tread edges may indicate
wheel misalignment. If your car needs alignment or suspension work, have it
done before you drive off with a new set of tires. Taking a “big
picture” approach to protecting your tire investment will reap many
rewards for miles to come.
Proper Tire Inflation
Proper tire inflation pressure is the specified air pressure given by a
carmaker for a certain tire on a specific vehicle. This pressure specification
should not be confused with a tire’s maximum pressure, which is usually listed
on the tire’s sidewall. Some vehicles may specify different pressures for the
front tires and the rear tires.
Correct inflation pressure is critical for good fuel economy, safety, maximum
tire life, and proper vehicle handling performance.
Tips/Suggestions: For the small amount of time it takes, checking tire
inflation at least once a month is one of the best investments you can make to
get the maximum life out of your tires. Proper inflation can also improve gas
mileage by more than 3%, when maintained regularly. You may want to check your
tires more often during the winter months. Tires will lose about 1 psi of
pressure for every 10 degrees Fahrenheit of temperature drop.
Keep an accurate tire pressure gauge in your car’s glove
box (many gauges at “air stations” give false pressure readings) and
check the tire pressure when the tires are cold. Never trust the appearance of
a tire as a gauge for inflation. A tire could be 10 psi low on pressure and not
appear to be low on air. Use the recommended inflation pressure listed in your
vehicle’s owner’s manual or on the inflation sticker found on the driver’s door
jamb. While you’re at it, don’t forget to check the spare. There’s nothing more
annoying than a flat spare when you have a flat tire.
Tire rotation refers to the regular practice of switching the position of each
tire on the car.
Tire rotation helps to equalize tread wear and is critical to gain the maximum
life from your tire investment.
Tips/Suggestions: Refer to your owner’s manual for the recommended rotation
interval and pattern; generally a rotation interval of 5,000 miles is
recommended. The rotation pattern varies with different makes and models, which
shows the tire locations during rotation. Some vehicles have different size
tires on the front and back or directional tires. Tire rotation time also offers a good
opportunity to have the tires and wheels balanced. It is another step you can take to maximize
your tire investment.
Spare Tire & Wheel
Spare tires and wheels may come in full-size versions (the same tire size as is
used on the car) or as a “mini-spare”, a compact tire and wheel
assembly that conserves storage space. Many cars are equipped with temporary
spare tires and wheels, which are noticeably different from regular tires and
wheels. Some require higher inflation pressure, with most mini-spares requiring
60 psi and have a maximum speed of 45 mph.
The spare tire serves as a back up in case your car has a flat.
Tips/Suggestions: It is also a wise
idea to become familiar with changing a tire on your car, before you have to.
Acquaint yourself with the location of the jack and its handle, where the jack
is supposed to contact the vehicle when raising it, the lug wrench, the
location of the key for the wheel locks (if equipped), and how to access the
spare tire. Too often, motorists are surprised to find essential tire-changing
tools damaged or missing. It is a good idea to make a practice run at changing
a tire, so you’re on top of things when your car has a real flat. If your car
has a temporary spare, drive your car within the speed limits specified on the
Wheel locks function like regular lug nuts, with the exception of requiring a
special key tool for removal and installation.
Wheel locks help to prevent theft of expensive aluminum and alloy wheels, along
with their tires. Wheel locks are also available for spare tires.
Tips/Suggestions: Keep the key to your wheel locks in a convenient place
(glove box) so it will be available when you need it. If the key is used when
your car is in for service, check to make sure that it has been returned to the
place where you keep it. Finding out that you don’t have the key when it is
time to change a flat tire can turn a minor inconvenience into a major
Wheel balance refers to the proper distribution of weight around a revolving
tire and wheel assembly. Poor wheel
balance can have a marked impact on both your car and your safety.
Purpose: Proper wheel balance ensures that the wheels,
while spinning, do not have a heavy spot that can cause vibration and premature
wear of tires, struts, shocks and other steering and suspension components.
When combined with proper wheel alignment, balanced wheels ensure smooth and
Tips/Suggestions: The most common signs of unbalanced tires are vibration
and noise problems. When driving with an out-of-balance wheel, the wheel
literally bounces down the road rather than spinning smoothly. This can affect
the speed, handling and mileage of your car. Many of today’s cars have
lightweight suspension systems and are therefore, more sensitive to imbalance
than older cars. It is a good idea to have your car’s wheels balanced when
rotating the tires, about every 5,000 miles. It is not uncommon for
wheels to lose a wheel weight from time to time; so periodic balancing
minimizes the impact of unbalanced wheels on your car.
Wheel alignment consists of a series of interrelated measurements and
adjustments that bring a vehicle’s steering, suspension and on-road driving
characteristics into manufacturers’ specifications.
Purpose: Proper wheel alignment reduces tire wear, improves
fuel economy and handling, while increasing driving enjoyment and safety.
Tips/Suggestions: Have your car’s alignment checked once a year. Normal
wear and road conditions can take their toll on your car’s steering and
suspension system, possibly throwing the alignment settings out of
specifications. For best results, seek a reliable alignment shop and qualified
technician who can perform a four-wheel alignment on your car.
alignments have always been associated with only the front wheels, but no
longer. Consider this: The rear wheels set the direction of vehicle travel; the
front wheels steer the vehicle. Having all four wheels checked ensures
directional harmony as your car goes down the road. Some common symptoms of
your car needing an alignment include uneven tire tread wear, pulling to one
side, wandering, and an off-centre steering wheel. While having your car’s alignment set, it
also serves as the perfect opportunity to balance your car’s wheels.