How do I tell "normal" Tyre wear from "abnormal" Tyre wear?
How often do I really need to have my wheels aligned?
What's the difference between a front-end alignment and a
four-wheel alignment (besides the price)?
I'm buying a new set of Tyres. Should I have them balanced?
Is it still necessary to
rotate the Tyres every so often?
How much air should I put in my Tyres?
When I'm driving down the highway, my car wants to pull to
one side. How come?
I feel a high speed shimmy in the steering wheel. What's
causing it?
When I buy replacement Tyres for my vehicle, do they all
have to be the same size?
Why are almost all Tyres today radial ply Tyres?
What are all-season, asymmetrical and directional Tyres?
What do the various ratings on a Tyre mean?
When I replace the Tyres on my vehicle, do I have to use
the same size as the originals?
How do I change a Flat Tyre?
How do I check Tyre Pressure?
What are the kinds of Tyres available?
How can I maintain my Tyres?
How should I Replace my Tyres?
Steering wheel vibrates. What's going on?
Car pulls to one side while moving. Why?
Tyres are wearing more in the center than on the edges.Why?
Tyres wobble while driving. Why?
Wheel shimmy exists. Why?
Car seems to bounce too much. Why?
|
| How do I tell "normal" Tyre wear from "abnormal" Tyre wear? |
Answer:It's getting harder to tell because of changes in tire and suspension designs. But as a
rule, "normal" wear is when the tread wears evenly across the entire surface of
the tire. The edges and center sections of the tread wear down at approximately equal
rates, and no bumpy, directional, feathered or cupped wear patterns develop on the tread.
What's more, both front tires and both rear tires wear at approximately the same rate.
Front and rear tires usually wear at different rates depending on which end is doing the
driving. The front tires on front-wheel drive cars and minivans, for example, wear at a
much faster rate than the rear tires. The rear tires on rear-wheel drive performance cars
or vehicles driven by someone with a heavy foot also tend to wear out much faster than the
ones up front. But this is "normal" for the way in which the vehicle is driven.
Heavy shoulder wear on the tires is also considered "normal" if a vehicle is
driven hard around corners. Rapid shoulder wear on the front tires is also
"normal" on some trucks and minivans because of the steering geometry of the
vehicle. The front wheels are supposed to "toe out" with respect to one another
when they are turned to either side to compensate for the different path the inside and
outside wheels follow when turning a corner. Some vehicles are better designed than others
to accomplish this. Those that aren't tend to produce more shoulder wear than those that
do. Rotating your tires frequently (every 8,000 miles or so) can help to equalize this
kind of wear between tires.
Abnormal wear: "Abnormal" tire wear is any type of wear that results from a
suspension or alignment problem, an internal tire fault, or driving on underinflated or
overinflated tires. Abnormal wear would be where the inside or outside edge or shoulder of
the tire shows extreme wear, but the rest of the tread shows little wear. This is called
"camber" wear and results from the tire leaning in or out (it should be straight
up and down when rolling down the road). Camber wear can be caused by suspension
misalignment, a bent strut, a mislocated strut tower (often the result of unrepaired
collision damage), a weak or broken spring, a bent spindle, or collapsed or damaged
control arm bushings. The suspension should be inspected for worn or damaged parts, and an
alignment check performed to determine what needs to be fixed to correct the problem. If
the tread develops a feathered or directional wear pattern where the tread feels smooth
when you run your hand across it one way, but feels rough when you rub it in the opposite
direction, you have a "toe" wear problem. Toe refers to the parallelism between
the wheels as the roll down the road. If the wheels are toed in or out with respect to one
another, the tread will scuff and develop a feathered wear pattern. This may be due to toe
misalignment, worn tie rod ends, worn idler arms, bent steering linkage or bent steering
arms. As with camber wear, the suspension should be inspected, and the alignment checked
to determine what's causing the problem. A "cupped" wear pattern on the tires
can be caused by a wheel and tire that are out of balance or by weak shock absorbers or
struts. This type of wear occurs because the wheel bounces up and down as it rolls down
the highway. The cure here is to have the wheel balanced or replace the worn shocks or
struts. If the center of the tread is worn more than the shoulders, it may be the result
of overinflation. You're putting too much air in your tires, causing them to bulge out in
the center and wear unevenly. Refer to the recommended inflation pressures in your owner's
manual or on the tire inflation decal in the glovebox or door jamb. If the shoulders of a
tire are worn more than the center, it may mean the tire doesn't have enough air in it.
Underinflation shifts the weight carried by the tire to the edges of the tread causing the
shoulders to wear more than the center. As with overinflation, refer to the recommended
inflation pressure for your vehicle. Note: As mentioned earlier, heavy shoulder wear can
also be caused by hard driving, especially on winding or curving roads. In this case,
nothing abnormal is indicated, and the only correction that's needed is a change in your
driving habits. Some low profile performance tires have a tendency to develop what's
called a "heel and toe" wear pattern if they are not rotated every 5,000 to
8,000 miles. This is caused by tread flex and the belt design of the tires. If tires with
this kind of wear tendency are not rotated, the tread may develop a washboard wear pattern
that causes annoying vibrations and/or noise at speeds above about 40 mph. Once the wear
pattern is established, it may be too late to reverse it by rotating the tires. Replacing
the tires (and switching to a brand or design that is less "quirky") may be the
only way to cure this kind of wear problem. |
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| How often do I really need to have my wheels aligned? |
Answer:Once. If the wheels on your vehicle are correctly aligned when the vehicle is manufactured
at the factory, they should not change alignment until something in the suspension wears
out or is damaged. Alignment doesn't change. The only thing that changes it is wear or
damage. Hitting a pot hole or a thousand pot holes won't knock your suspension out of
alignment unless you hit something hard enough to actually bend metal. That really doesn't
happen very often, so having the wheels aligned periodically is a waste of money. On the
other hand, there are valid reasons for having the alignment checked periodically:
• If your tires are wearing abnormally, alignment should be checked to
find out why. Chances are something is amiss and needs to be readjusted or replaced. It
only takes a 1/8 inch of toe misalignment to drag the front tires sideways the equivalent
of 28 feet for every mile traveled!
• If you're buying a new set of tires and want to maximize tread life,
it's a good idea to have the alignment checked as insurance. Even if the factory alignment
is within the acceptable range specified by the vehicle manufacturer, there's often room
for improvement. Resetting alignment to the "preferred specs" (which means the
midrange or optimum specs) will usually extend tire life -- sometimes significantly.
Considering the high cost of many performance tires today, assuring maximum tire life with
an alignment is money well spent.
• If you're experiencing any kind of steering or handling problem, an
alignment check may be necessary for diagnostic purposes. An important aspect of aligning
the wheels is performing a preliminary alignment inspection of the suspension and steering
linkage. This is necessary to determine if there are any worn, damaged or mislocated
parts. It's impossible to realign worn or damaged parts so any such parts must be replaced
before the wheels can be realigned.
• Wheel alignment is also required when certain suspension and steering
components are replaced. On most cars with MacPherson struts, the front wheels should be
realigned if the struts are replaced (NOTE: This is not necessary on certain import
vehicles that have replaceable strut cartridges). Alignment is also required if the tie
rods, tie rod ends, idler arm, steering links, control arms or control arm bushings,
steering knuckle or steering rack have been replaced.
• Another benefit of having the wheels aligned is to assure optimum
handling and traction for driving safety. Camber, in particular, is a very important angle
with respect to keeping the tire's treads in full contact with the road. Tires that lean
in or out ride on the shoulder and reduce traction, cornering ability and tread life.
Camber can even affect braking. Uneven camber or caster side to side can make a vehicle
lead to the left or the right. |
| Top |
| What's the difference between a front-end alignment and a
four-wheel alignment (besides the price)? |
Answer:The "completeness" or thoroughness of the job. A front-wheel alignment
only aligns the front wheels. A four-wheel alignment aligns all four wheels. All vehicles
can benefit from a four-wheel alignment, but it is especially important on front-wheel
drive cars and minivans as well as rear-wheel drive cars that have independent rear
suspensions.
Until a decade ago, two-wheel alignments were the norm for all cars and trucks. But the
arrival of front-wheel drive changed all of that. It's always been important to align all
four wheels to one another because the rear wheels can have just as much influence on
steering as the ones up front do. But on most rear-wheel drive vehicles, there are no
adjustments on the rear suspension. So even though the need to check rear wheel alignment
is there, there's not much a technician can do if the rear wheels aren't true with respect
to the ones up front.
If the rear axle is cocked slightly to one side or the other, it creates a "thrust
angle" that causes the steering to pull slightly to one side or the other. If the
misalignment cannot be corrected by repositioning the rear axle, a "thrust angle
alignment" (aligning the front wheels to the imaginary angle created by the rear
axle) can at least make a vehicle steer straight.
The arrival of front-wheel drive in the 1980s increased the awareness of the importance of
rear-wheel alignment. Though many of the early front-wheel drive vehicles lacked much in
the way of "factory" adjustments (front or rear!), aftermarket kits allow most
types of alignment problems to be corrected. Most newer front-wheel drive cars and trucks
now have factory adjustments for the rear suspension.
According to a recent survey by Brake & Front End magazine, a trade publication for
alignment shops, 44% of all alignments jobs being performed are now four-wheel alignments.
Those who are still doing two-wheel alignments say price is a big issue with consumers.
They don't want to pay more for a four-wheel alignment. Others say they don't have the
proper equipment or training to do four-wheel alignments.
Two-wheel alignments still appeal to many technicians because aligning two wheels doesn't
take as much time as aligning four wheels, nor does it require very sophisticated
alignment equipment. A toe stick and a camber/caster bubble gauge are all that's needed to
do a "quickie" alignment job. But aligning only the front wheels is like asking
your dentist to only clean your upper teeth. All four wheels need to be checked because
the rear wheels are just as important as the ones up front -- even on rear-wheel drive
vehicles with nonadjustable rear suspensions. |
| Top |
| I'm buying a new set of Tyres. Should I have them balanced? |
Answer:Yes. Balancing helps to guarantee a smooth ride at highway speeds, and it helps to
maximize tire life. An out-of-balance tire can be very annoying because it produces a
shake that increases in intensity the faster you go. The up-and-down shaking of the wheel
is hard on the suspension, not to mention your nerves, and also increases tread wear. An
out-of-balance tire can develop a cupped wear pattern. So do yourself and your tires a
favor and have them balanced.
Almost all service facilities and tire stores today use
an off-car electronic spin balancer to balance the wheels.
The tire and wheel are mounted on the balancer, then spun
to find any heavy spots on the wheel. The balancer then
indicates where weights (and how much weight) need to be
placed to counterbalance the heavy spot. Off-car spin balancers
actually check two kinds of balance, "static"
and "dynamic." Static imbalance causes a wheel
to shake up and down as it spins, so static balance is achieved
when both halves of the tire wheel assembly weigh exactly
the same. Dynamic imbalance causes a tire and wheel to shake
back and forth or sideways as it spins. Dynamic balance
is achieved when the front and back sides of the wheel and
tire weigh the same. |
| Top |
| Is it still necessary to
rotate the Tyres every so often? |
Answer:There are two schools of thought on this subject. Rotating the tires, which is recommended
by all tire manufacturers, involves changing their position on the vehicle from one wheel
location to another. This helps to even out tire wear between all the tires so the tires
last longer and do not develop abnormal wear patterns. This may be recommended every 8,000
to 15,000 miles.
On front-wheel drive cars and minivans, the front wheels tend to wear at a much faster
rate than those on the rear. After 50,000 or 60,000 miles of driving, the front tires may
be worn out while the ones on the back may still have half or more of their tread life
remaining. By rotating the tires front to rear and side to side, differences in wear
patterns between the wheel locations spreads the wear out and more or less wears the tires
evenly -- or so the theory goes. Consequently, tires that would have lasted only 50,000 or
60,000 miles on the front of a front-wheel drive car may last 70,000 or 80,000 miles. But
on the other hand, the tires on the rear that may well have gone 100,000 miles only last
70,000 or 80,000 miles.
Those who say rotating tires is a waste of time argue that it makes more sense to replace
the front tires on a front-wheel drive car or minivan when they wear out, but to leave the
back tires alone -- especially if you're putting a lot of miles on the vehicle or plan to
keep it a long time. The back tires will probably last as long as two sets of front tires,
so in the long run you end up buying the same number or possibly even fewer tires by not
rotating. Plus, you've saved the time and money that would have been spent on rotating the
tires. This argument doesn't fly in the case of certain low profile performance tires that
have a tendency to develop a heel-and-toe wear pattern if left in the same wheel position
too long.
Tire rotation patterns: For rear-wheel drive cars and trucks, the recommended tire
rotation pattern is to rotate the front wheels to the opposite side on the rear, and move
the rear wheels to the same side on the front. For front-wheel drive cars and minivans,
the recommended tire rotation pattern is to rotate the rear wheels to the front on the
opposite side, and move the front wheels to the rear on the same side. If your vehicle has
"directional" tires (small arrows or triangles indicating the direction of
travel), the wheels must not be switched side to side. They can, however, be rotated front
to rear on the same side. If the front and rear wheels and/or tires on your vehicle are of
different size, then rotation is out of the question. |
| Top |
| How much air should I put in my Tyres? |
Answer: It depends on the vehicle application, the size of the
tires, how much weight is on the tires, and whether fuel
economy is more important to you than a smooth ride. Listed
in the owner's manual or on a decal in the glovebox or
door jamb in every vehicle are the recommended inflation
pressures from the vehicle manufacturer. For most passenger
cars, minivans and minipickups, the recommendations range
from 27 to 32 psi. For fullsize pickup trucks and sport
utility vehicles, the recommended inflation pressures
tend to be about 5 to 8 psi higher to reflect the larger
tire sizes and greater weight of these vehicles. It's
important to note that the recommended inflation pressures
may differ for the front and rear tires.
The manufacturer's recommendations are not necessarily the optimum inflation pressure for
your tires, but are generally the best for all-round driving. Adding a couple of extra
pounds of pressure will decrease the rolling resistance of the tires and make a slight
improvement in fuel economy -- but it will also make the tires harder which in turn may
cause a somewhat rougher or harsher ride.
If you're carrying a lot of extra cargo, car pooling, hauling a lot of stuff in the back
of a pickup or towing a trailer, a few extra pounds of pressure would be recommended to
offset the added weight. Add the extra pounds to the rear tires. Warning: Never exceed the
maximum inflation pressure specified on the sidewall of the tire. This number is the
maximum pressure the tire is designed to safely handle. Higher pressure increases the risk
of tire damage (when hitting a bump) or tire failure.
Why check? All tires leak a little air over time, with some losing up to half a pound a
month. If you're losing more air than this, you probably have a leak (possibly a rim leak
or a porosity leak in an alloy wheel). For this reason, tire pressure should be checked at
least once a month -- and certainly before taking a long trip or driving at sustained
highway speeds. Underinflated or overinflated tires can wear unevenly. Underinflation also
increases tread wear dramatically. Warning: Underinflation may also increase the risk of
tire failure or a blowout. When a tire with too little air in it (say 12 to 18 lbs.) is
driven at highway speeds, the sidewalls are forced to flex excessively. This builds up a
lot of heat in the tire which may cause it to fail.
How to check? Recommended tire inflation pressures are always for cold tires, which means
you should check the tires in the morning before the vehicle has been driven. Driving
heats up the tires and causes the air inside to expand. If you check the tires right after
driving, therefore, the readings will be at least several pounds higher than normal.
Internal tire pressure will also vary with the ambient (outside) air temperature. Hot
weather raises air pressure inside the tires, while cold weather lowers it. So air may
have to be added or vented from the tire to compensate for seasonal variations as well.
Use an accurate tire gauge to check your tires. Don't rely on the built-in gauge on a gas
station air hose or compressor (which tend to be very inaccurate). And never rely on your
eyeballs alone to "judge" the amount of pressure in your tires. The sidewalls on
radial tires typically bulge quite a bit even when the tire is properly inflated. If you
keep adding air until the bulge is gone, the tire will be seriously overinflated.
Likewise, don't wait until the tire is nearly flat to add air. It's nearly impossible to
tell the difference between a tire that has 10 lbs. of air from one that has 20 lbs. of
air. Use a gauge to check the tires regularly, and add or vent air as needed to keep the
pressure within a couple of pounds of the amount recommended by the vehicle manufacturer.
Note: Tire inflation pressure should be more or less equal side-to-side. A difference of
more than a couple of pounds may be enough to cause a noticeable steering or brake pull. |
| Top |
| When I'm driving down the highway, my car wants to pull to
one side. How come? |
Answer: A steady steering pull or "lead" to one side
may have any of a number of causes. The most likely cause
is wheel misalignment. This may be due to rear wheel toe
or axle misalignment, front wheel camber misalignment,
too much cross camber or caster alignment (more than a
degree of difference side to side), or someone having
"aligned" the front wheels without the steering
wheel being properly centered beforehand. In any event,
it will probably be necessary to have the alignment checked
to diagnose and correct the problem -- unless one of the
following is causing the pull:
• An underinflated front tire on one side. Check tire pressures and
make sure they are the same side-to-side (no more than a couple of pounds of difference).
• Mismatched tires. Tires of different size, aspect ratio or even tread
pattern on one side can create enough of a difference in rolling resistance to cause a
pull.
• A weak or sagging spring. Measure and compare ride height on both
sides of your vehicle (measure at the fender openings). If one side is an inch or more
lower than the other side, chances are you have a spring that needs to be shimmed or
replaced.
• A dragging brake. This can be caused by a frozen or sticking disc
brake caliper that doesn't allow the pads to kick back out from the rotor or weak or
broken return springs in a drum brake that don't pull the shoes back from the drum.
Another possibility here might be a packing brake that isn't fully releasing on one side.
• An uneven load. If you, your significant other or a passenger is
causing your vehicle to lean to one side, it can cause the steering to lead in that
direction. Don't laugh, a few hundred extra pounds can make a big difference in a small
vehicle -- especially if the weight isn't evenly distributed side-to-side. If you can't do
anything about the extra weight, it is often possible to compensate by having the wheels
realigned with a "simulated" load positioned in the vehicle. Of course, then
your vehicle may lead in the opposite direction if the extra weight is removed.
• Excessive road crown. Roads are usually sloped (crowned) from the
center towards the sides for drainage. If you spend a lot of time driving on highly
crowned roads and find the constant lead to the outside shoulder annoying, you can have
the wheels realigned to compensate for the excessive crown. Adding or subtracting camber
from one wheel or the other to create a difference in the cross camber alignment of your
front wheels can counteract this kind of problem. |
| Top |
| I feel a high speed shimmy in the steering wheel. What's
causing it? |
| Answer:A high speed shimmy is usually caused by a wheel that's out of balance or a bent
wheel. The first thing to check for would be a bent wheel. Raise the front of the vehicle
off the ground and rotate each wheel by hand. If you see any sideways or in and out
movement of the wheel, it is bent and needs to be replaced. Warning: Although some people
claim they can straighten bent wheels, doing so is risky -- especially with aluminum alloy
wheels. Replacement is the safest option (but also expensive). If you don't see any
sideways movement in the wheel, it doesn't necessarily mean the wheel is straight. There
may be just enough sideways runout to cause a shimmy, but not enough to see. To find this
kind of problem, you'll need a dial indicator. More than about .050 inch of sideways
runout can be enough to cause a problem. If the wheels seem to be straight, have the
balance of both wheels checked (or rebalanced). If that fails to cure the shimmy, you may
have some kind of tire problem due to defective belt alignment or tire construction. Other
causes may include loose or improperly adjusted wheel bearings, insufficient caster
alignment (check and readjust alignment as needed), or a worn steering damper (on trucks
or other vehicles equipped with a steering stabilizer). |
| Top |
| When I buy replacement Tyres for my vehicle, do they all
have to be the same size and does it affect the braking system (ABS)? |
| Answer: Yes and no. If
you want to rotate the tires on your vehicle to maximize tread life, then all the tires
have to be the same size. Rotating the tires every 5,000 to 7,500 miles is a good idea,
especially on front-wheel drive cars and minivans where the front tires tend to wear out
long before the ones on the back. Wide, low profile tires also tend to develop unusual
wear patterns if left in the same wheel position for their entire life. If you don't plan
to rotate your tires, however, then the front fires can be a different size than the ones
on the back. But the tires on both front or both rear wheels must be the same size for
proper handling and braking. Mismatched tires side-to-side can cause a vehicle to lead to
one side and/or to pull when braking. Caution: Never mismatch types of tires either on the
front or rear wheels. A bias ply tire should never be paired with a radial tire, and vice
versa. Likewise, tread design, belt type and overall tread wear should be the same (or
similar) side-to-side for proper handling, steering and braking. Intermixing different
brands and styles of tires may cause similar problems in some instances. As for the size
of replacement tires, some people will try to use anything that fits. This may not be a
good idea because a vehicle's handling, steering and braking characteristics can all be
adversely affected by using tires that are too large or too small for the application.
Some people may want oversized tires on their rear drive wheels to improve fuel economy.
Switching to a larger diameter tire reduces the number of revolutions per mile. But it
also affects the accuracy of your speedometer and odometer readings. Others may want wider
or larger tires on the rear drive wheels to improve traction or to achieve a special kind
of "look." Wide tires, however, typically provide reduced traction on wet roads.
Clearance problems can arise, too, if the tires are too wide or too large. They may rub
against the body when turning or when the vehicle hits a bump. This can not only damage
the vehicle but also the tires, possibly causing a blowout. On cars and trucks that have
antilock brakes (ABS) equipped cars and trucks, most vehicle manufacturers say replacement
tires should be the same size as the originals. This is necessary because the diameter of
the tire affects how the wheel speed sensors read, which in turn affect the operation of
the ABS (and traction control) system. Changing to a larger or smaller diameter tire, or
installing different sized tires front and rear can upset the operation of the ABS system.
This may create braking problems and/or cause the ABS warning light to come on (which
means the system is deactivated). Vehicles with all-wheel drive or full-time four-wheel
drive must also run the same sized tires front and rear to maintain the proper drive
relationship between axles. If one set of tires is larger or smaller than the others, it
will create slippage between the front and rear axles that will accelerate tire wear and
adversely affect handling. |
| Top |
| Why are almost all Tyres today radial ply Tyres? |
| Answer:Because radial ply tires are better than bias ply tires. The belts are layers of woven
reinforcing fiber inside the tire under the tread. The belts give the tire strength, keep
the tread from squirming and help resist punctures. The belts may be fiberglass, steel,
nylon, rayon or aramid fiber. In bias ply tires, which were common before radials were
invented, the innermost plies crisscross like an "X" as they run from bead to
bead (side to side), while the outermost plies run lengthwise around the circumference of
the tire. This makes a relatively firm tread, but it also increases rolling resistance.
And anything that increases rolling resistance increases fuel consumption. The innermost
plies in radial tires, by comparison, run sideways between the beads. This makes the tire
more flexible, which reduces rolling resistance and improves fuel economy. Changing from
bias ply to radial ply tires can improve fuel economy 10 to 15%, so that's the main reason
why most tires today are radials. The increased flexibility of radial tires also helps
improve traction and cornering. Because the tire is more flexible, it is better able to
maintain tread contact when cornering. This also allows lower aspect ratio tires (shorter
sidewalls) which provide better handling performance. |
| Top |
| What are all-season, asymmetrical and directional Tyres? |
| Answer: Essentially an all-season tire is a
tire with a slightly aggressive tread pattern
that provides good year-round wet and dry
traction characteristics. It tends to be a
bit harsher and louder than ordinary tires,
but not as harsh or loud as a snow tire. Some
all-season as well as performance tires have
a directional" tread pattern. Directional
tires have a "one-way" tread pattern
that are optimized for the direction the tires
rotate on the car. They must therefore be
mounted on either the left or right side.
Little arrows or triangles on the sidewall
indicate which way the tire is supposed to
turn. The tread blocks and grooves are angled
to optimize handling. They also do a good
job of channeling water out from under the
tire on wet surfaces to reduce hydroplaning
and improve wet traction. Directional tires
can be rotated front-to-rear but cannot be
rotated side-to-side. Another variation in
tread design you'll see is "asymmetrical"
tires. Tires with an asymmetrical design mix
tread patterns or put more rubber on one side
of the tread than the other in an effort to
make one tire out of two different tread patterns.
Some combine a slick-like smooth tread on
half the tire (to improve traction) with a
block pattern on the other half (for directional
stability). |
| Top |
| What do the various ratings on a Tyre mean? |
Answer: On the sidewall of every tire are a number of ratings: traction, treadwear,
temperature, speed and load. These tell you something about a tire's performance and wear
characteristics so you can select a tire that will satisfy your driving needs as well as
the requirements of your vehicle.
Traction ratings: This is a rating of a tire's ability to stop on wet pavement as measured
under controlled test conditions. It does not indicate a tire's cornering ability or its
dry stopping traction. The DOT rating scale is A, B or C, with A being best and C the
minimum acceptable standard. An "A" wet rating doesn't necessary mean a tire
won't "hydroplane" (a dangerous situation wherein a tire loses contact with the
road when water gets under the tread and lifts it off the road). Hydroplaning can be a
problem with worn tires or those with wide treads that lack sufficient groove area to
handle water. Some tires are specially designed for wet weather driving and to resist
hydroplaning. Goodyear, for example, introduced its "Aquatread" tire several
years ago that features a deep center groove designed to channel water out from under the
tire. Other tire manufacturers have introduced their own versions of this design, and most
provide much better traction on wet roads than standard tires -- even all-season tires.
Tread wear ratings: Tread wear is a tough thing to measure because things like inflation
pressure, loading, the type of driving done, the type of roads driven upon, wheel
alignment, wheel balance, etc. all affect tread life. Because of this, the DOT tread wear
grading is based on a comparison of how a given tire wears compared to others under
controlled test conditions. The resulting numbers, which may range from 100 to nearly 400,
can be used to compare one tire to another. An important point to keep in mind here is
that a tire that's formulated with a harder rubber compound to maximize tread life
probably won't provide as good a dry traction as a "softer" tire that doesn't
have as high a tread wear rating. You can't have it both ways, and the price for improved
traction is usually reduced tread wear.
Temperature ratings: This is a rating that gives an indication of a tire's resistance to
generate heat and its ability to dissipate heat under controlled test conditions. Heat is
bad because it can cause the rubber to deteriorate and fail. The Department of
Transportation (DOT) ratings for temperature are A, B and C. A is the best rating while C
is the minimum acceptable standard. The temperature rating can be found on the tire's
sidewall.
Speed ratings: One thing every performance-conscious tire buyer should keep in mind is the
need for speed rated tires. Not everybody needs them, of course, but for those who do,
they're a must from a safety standpoint. There has been some confusion over speed ratings
because of recent changes. Speed ratings are not required by law. Even so, U.S. tire
manufacturers have adopted the European rating system partly to convince consumers that
domestic-made tires are as good as their European counterparts, and partly to assure the
public of a certain margin of safety.
Load carrying capacity: The maximum load carrying capacity of the tire is specified on the
tire's sidewall in pounds at the maximum inflation pressure. When inflating tires, do not
inflate to the maximum inflation pressure. Use the recommended inflation pressure listed
in the vehicle owner's manual, on the door jam or on the glovebox tire inflation decal. |
| Top |
| When I replace the Tyres on my vehicle, do I have to use
the same size as the originals? |
Answer: On ABS-equipped vehicles, all vehicle manufacturers recommend using the same size
and aspect ratio tire as the original. ABS systems monitor the rotational speed of the
tires through individual wheel speed sensors. Changing to an oversize tire with a taller
diameter than stock would cause the tires to rotate at a slightly slower speed relative to
vehicle speed than the stock tires. Changing to a low profile tire with a shorter diameter
would cause the tires to rotate at a slightly faster speed relative to vehicle speed.
Though the difference either way isn't much, it may be enough to upset the calibration of
the ABS system and have an adverse effect on its ability to detect and prevent skids.
Another reason for not changing tire sizes is because it can affect the speedometer,
odometer and transmission shift points on a vehicle with an electronic automatic. Oversize
tires will make your speedometer read slower than normal (which may get you a speeding
ticket unless you have the speedometer recalibrated to compensate for the change in tire
size!). Smaller diameter tires will make the speedometer read faster than normal, and
increase the mileage readings on your odometer at a faster than normal rate. All this
doesn't mean you can't change tire and wheel sizes, however. If you maintain the same
overall tire diameter as before, you can switch to larger wheels with a shorter aspect
ratio tire. This is the basic idea behind "Plus 1, Plus 2" tire and wheel
sizing. Replacing a stock 14-inch wheel and 70 series tire with a 15-inch 60 series tire
would be Plus 1. Plus 2 would be moving up to a 16-inch wheel and possibly a 50 series
tire. Plus 3 would be going to the new 17-inch tire and rim combination -- which could
turn out to be a Plus 4 application if the vehicle originally had 13-inch wheels.
Aspect ratio: The "aspect ratio" of a tire is the ratio of its section height to
its section width. The smaller the number, the shorter the sidewall and the wider the
tire. Low aspect ratio tires started with 60 series some time ago, then progressed to 50
series and now 45, 40 and even 35 series tires. Shorter aspect ratio tires (60 and less)
are usually considered to be performance tires because they lower vehicle ride height,
have a wider tread and put more rubber on the road to improve handling. But the shorter
the sidewall, the harsher the tire rides. A tire's ability to support a given load depends
on its air volume. If you go to a lower aspect ratio tire with a shorter sidewall, the
tire must be wider to maintain the same air volume. If you just go to a shorter aspect
ratio tire without increasing width, the load carrying capacity goes down. That's why when
you go from a standard wheel to a Plus 1 wheel, the rim is usually wider to accommodate a
wider tire. It's important to follow the tire manufacturer's recommendations as to load
capacities when going to larger wheel and tire sizes. There's no hard rule that says you
have to drop 10 points in aspect ratio when increasing wheel size one inch, but that's the
general recommendation. |
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| How do I change a Flat Tyre? |
Answer: Changing a flat can be a miserable experience for anyone. But if you have a
jack, a lug wrench and a spare tire, you are half way there.
1) First Steps: When you're driving and feel the rumble of a flat tire, slow down, turn on
your hazard lights and try to park the car on level ground as quickly as possible. Put the
automatic transmission into park and put the emergency brake on. If you have a manual
transmission, leave it in first gear and pull the emergency brake. If you have to park on
even a slight incline, try to find a heavy object to wedge up against the good tires. This
will help to keep the car from rolling when you have it jacked up. Once you've parked,
take out the lug wrench, jack and the spare tire from the trunk. Make sure the spare tire
has enough air in it.
2) Remove the hubcap and loosen the lug nuts: Pry off the hubcap with a screwdriver.
Sometimes the lug wrench has a screw driver at the end of it. If it does, use that. Some
cars don't have hubcaps at all. Now use the lug wrench to loosen the lug nuts, which are
the hexagonal bolts under the hubcap. If the lug nut has an L on it, turn clockwise. If it
has an R or doesn't have anything on it, turn counterclockwise. Try to loosen the nuts an
equal amount. Very important: Don't remove the lug nuts yet. Just loosen them.
3) Jack Up the Car: Put the jack on the ground near the flat tire, under the car frame.
Make sure it is under something structural that can support the weight of the car. Start
pumping the jack, so that the top of it reaches the bottom of the car. When it does, keep
going until the flat tire lifts off the ground. If the car seems unstable, lower the car,
reposition the jack and try again. Very important: Never get under the car when it is
jacked up.
4) Change the Tire: Now that the flat tire is in the air, remove the lug nuts and place
them in the upturned hub cap, or someplace easy to reach later. With all the lug nuts
removed, pull the tire off by pulling it toward you. It will be heavy, so be careful it
doesn't fall on you. Put the spare tire on, positioning it so that the holes line up with
the lug bolts. Replace the lug nets and tighten them, turning the opposite way you did
when you removed them. But don't tighten them all the way yet. Lower the car with the jack
so that the tire is just touching the car but not supporting the car's weight. Now tighten
the lugs the rest of the way so they are at least as tight as they were when you removed
them. Then lower the jack even further and remove it. Put the flat tire, hubcap, jack and
the lug wrench back in the trunk. Don't forget to remove the wheel blocks. Get your
original tire fixed as soon as you can. Your spare may be only good for short distances at
low speeds. |
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| How do I check Tyre Pressure? |
Answer:The main reason you should care about tire pressure is car performance. Cars are easier to
handle when the tire pressure is correct. Properly maintained tires also last longer, and
improve your gas mileage. The best way to maintain your tires is to buy an inexpensive
tire pressure gauge. The correct tire pressure is printed on the sidewalls -- or the
outside, non-tread part -- of your tires. It's also listed in your manual, and is often
listed on a sticker in the glove compartment or on the door jamb. The pressure is listed
in pounds per square inch, or PSI. Here is how to check your tire pressure:
1) Find an air pump at a gas station and park so that the air pump hose can reach your
tire comfortably. It's best to check tires when they are cold -- that is, when you haven't
been driving on them for very long.
2). Remove the tiny black valve cap on the valve that comes out of your tire, near the
hubcap.
3) Press the round part of the tire gauge firmly onto the valve. Try to press it so that
the hissing sound of air escaping from the tire stops while you're pressing. When it does,
you'll get an accurate reading..
4) Read the gauge like a thermometer. The highest number you see closest to the stem of
the gauge is the PSI. That number should match the recommended PSI for your tire.
5) If the gauge reading is higher than it should be, use your finger, or the notch on the
opposite side of most tire gauges, to release a bit of air by pressing it on the pin
inside the tire valve.
6). If the gauge reading is lower than it should be, use the pump to add more air. On some
pumps, you'll have to take the hose completely off the hose cradle to activate the pump.
Press the head of the air hose firmly onto the tire just like you did with the tire gauge.
7) Check your tire pressure with the gauge again, repeating your steps until you get the
PSI right.
8) Don't forget to replace the valve cap. |
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| What are the kinds of Tyres available? |
Answer:No tire can handle every road condition and driving style perfectly. Positive attributes
are always offset by negative factors, as the following list of tire types shows:
• All-Season Tires: The Jack-of-all-trades of the tire world, and, as a
result, they're the most compromised. They provide only adequate traction and handling,
but they have long tread life and a smooth, quiet ride. They're also relatively
affordable.
• Touring All-Season Tires: These tires combine good handling with a
civilized ride. Their performance oriented construction means that they're somewhat
noisier and harsher than regular all-season tires. They're also more expensive than
regular all-season radials, but last just as long. Some manufacturer's arbitrarily add
"touring" to a tire's name as a selling point.
• Performance Tires: Wider tread and lower profiles combine good looks
with good grip for precise, high-speed driving. Performance tires tend to have a harsh,
noisy ride, relatively poor wet traction, bad snow traction, and they wear out faster than
all-season radials. They're also much more expensive. The price of ultra-high performance
tires can cause your jaw to drop.
• Conventional Snow Tires: Have chunky, aggressive treads that dig down
to pavement covered by snow and ice. They're noisy and handle poorly on dry roads. They're
more expensive than all-season radials. They should last a long time, especially since
they're only on the car for one season each year. Studded snow tires have tiny metal studs
embedded in the tread for even better traction. (These days snow tire use is less common
than in past decades. If you live in a place where it snows, and you drive a rear-wheel
drive car, invest in a set of snow tires.)
• "High-Tech" Snow Tires: Have precision engineered tread
patterns and state-of-the-art multi-cell compounds which lend to good ice/snow traction
and stopping ability. They can be used all year, but they're noisy and somewhat clumsy on
dry pavement. They're expensive and wear out quickly.
• Light Truck Tires: Specifically designed for trucks and sport-utility
vehicles, yet they are as diverse as passenger car tires. "Highway ribbed,"
on-road tires emphasize civilized ride and handling, while aggressive "off-road"
or "mudder" tires have a loud, harsh ride and sloppy handling on pavement. Light
truck tires are more expensive than passenger car tires due to their larger sizes, higher
load ratings and heavy-duty construction. Deep treads mean that they'll last a relatively
long time.
• Rain Tires: Have a drainage channel in the tread that directs water
away from the tire's surface more efficiently than conventional drainage grooves.
• High Flotation Tires: Big, wide tires that people put on 4x4 trucks
and sport-utilities so they can drive on the sand without sinking. These tires have poor
traction in the ice and snow, so put those skinny, un-cool tires back on the truck for the
winter.
• Directional Tires: Have a "one-way" tread pattern optimized
for the direction the tires rotate on the car.
• Asymmetrical Tires: Combine multiple tread patterns in order to make
a more well-rounded performance tire.
• Self-Sealing Tires: Have a flexible inner-lining that seals around an
object if punctured, stopping air loss.
• "Twin" Tires: This setup employs two thin,
"half-width" tires which are mounted on a special wheel. If one tire goes flat,
the other "half" can still support the car.
• "Run-flat" Tires: Use special rubber compounds and
reinforced sidewalls that can support the car even when deflated -- allowing limited
travel.
• "Lifetime" Tires: Last for many years, as the name
suggests. These tires wear out very slowly while delivering adequate traction. |
| Top |
| How can I maintain my Tyres? |
Answer: There are some easy things you can do to prolong the life of your tires and improve
your vehicle's safety.
Keep your tires properly inflated -- correct air pressure is required for good handling
and traction, good fuel economy and even wear. The only way to determine proper tire
pressure is to use an accurate gauge. Tire pressure should be checked and corrected only
when the tires are cold; even a short drive can make your tires too hot for accurate
pressure readings. Don't inflate tires to the maximum pressure printed on the tire -- use
the tire pressure recommended in your vehicle's owners manual or tire information sticker
(located in the glove box, on the door post, or inside the fuel door). Remember to check
the pressure in your spare tire. See Checking your tire Pressure and How much air should I
put in my tires? in the AutoSite Garage for more details.
It's dangerous and illegal to drive on worn-out tires. Tires are worn out when their tread
has 1/16" or less remaining. Molded-in treadwear indicators, or "wear bars"
(raised, narrow strips of rubber in the drainage grooves), will become even with the tread
when it's time to replace the tire. Another way to figure out if your tread is worn out is
to insert the edge of a penny into a drainage groove -- hold the penny so the top of Uncle
Abe's head is pointing toward the tire's surface. If the top of Abe's head is still
visible, the tread is too shallow and it's time for new tires.
Regularly inspect your tires for irregular wear and sidewall bubbles. Irregular wear is
often caused by a worn or misaligned suspension, or improper inflation. Sidewall bubbles
are caused by a break in the sidewall and could cause a blow-out.
Irregular tire wear can be partially prevented by regularly rotating your tires (every
5-10 thousand miles is recommended). Some shops will do it for free if you buy your tires
from them. Even if you don't do it nearly as often as recommended, try to rotate your
tires at some point in their life. Check your owner's manual or service manual for the
exact rotation pattern for your vehicle.
Never drive on a flat or severely deflated tire -- this will crush the sidewall and
destroy the tire. It can even irreparably damage the wheel, especially if it's an alloy
wheel. Know the location of your jack, tools and spare. If you buy the car used, make sure
these things are still in the car. Replace your car's wheel wrench with a cross-shaped
wrench -- it'll make it much easier to remove the lug nuts that hold your wheels on. Also
try to keep a wheel chock (small piece of wood or a brick) in your car to brace one of the
car's wheels when you jack it up. Try to carry a small, flat piece of board as well. If
you have to change your tire on unpaved ground, place the board under the jack so it
doesn't sink. See Changing a Flat Tire for further details.
If your car has a temporary spare tire, note its limited operation speeds which are
indicated on the sidewall (generally under 50 mph). Only use this type of spare until it
is convenient to fix the flat. "Fix-a-flat" aerosol sealants and inflators can
fix a damaged tire temporarily. These products are very flammable. If you use one, attach
the warning sticker that comes with the product to the valve stem and inform your
mechanic.
A service station can fix a flat that was caused by a puncture to the tread by sealing the
puncture with a rubber plug. You can also buy a plug kit from an auto parts store and do
it yourself. Punctures in the sidewall cannot be repaired. Proper, permanent repair
procedures require a vulcanized patch to be placed over the puncture, on the inside of the
tire, but many shops do not do this.
Since tires affect your vehicle's performance, all four tires should be the same. If one
of them is damaged and you cannot replace it with a duplicate, then try to find the
closest approximation. Also, if all four tires can't be identical, then try to have the
two front and the two rear tires be the same. See Tire Mixing Rules and When I buy
replacement tires for my vehicle, do they all have to be the same size? in the AutoSite
Garage for more details. |
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| How should I Replace my Tyres? |
Answer: When your tires wear out, you have to decide how you're going to replace them. Often it's
not just a simple matter of buying the exact tires that came with the car -- they may have
been discontinued; may cost a lot more than a comparable brand; or may not fit your
driving style. Don't skimp on your tire purchase if you care about your car's ride and
handling. Conversely, if you only drive sedately and your car's expensive low-profile
performance tires have worn out, don't break the bank to replace them if a lesser tire
will fit. Determine if you want to stay with the same kind of tire that came with the car,
or upgrade to something better (and more expensive...). Price out similar tires made by a
few different manufacturers so you can find the best deal.
Three different charges are incurred when buying new tires. The first and the most
expensive is the basic cost of the tire. Then there is a fee to mount and balance your
tires. (Shop around, these fees vary widely.) There is also a nominal charge for new valve
stems. Many large retail stores mount and balance tires and provide lifetime rotations and
road hazard insurance for one surprisingly low fee. Any warranty is better than no
warranty, but don't make a tire purchase based on this criteria alone. A tire warranted to
go 70,000 miles might be a bad choice. Its hard rubber tread won't wear out quickly, but
won't provide good traction either. Also, basic tire warranties only cover defects in
workmanship and materials. It is difficult to prove that your driving style and lack of
maintenance weren't to blame for early wear-out. Modern tires are usually not defective
and do not often go flat -- "road hazard" or tire insurance is not necessary
unless your car is rolling on some very expensive rubber. |
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| Steering wheel vibrates. What's going on? |
Answer: The steering wheel vibrates at speeds of 45 to 60 MPH. You will also notice that the car
is vibrating or twitching down the road. This can be a very dangerous problem and should
not be ignored. Sometimes the problem only occurs when the brakes are applied. If this is
the case, diagnosis of the problem is easier.
The probable causes are:
1) Warped or damaged brake rotors and/or drums.
2) Loose wheel
lug nuts.
3) Out-of-balance wheel and tire assemblies.
4) Loose steering linkage.
5) Bent
or damaged wheels.
6) Severely worn or damaged tires.
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| Car pulls to one side while moving. Why? |
Answer: While
you are driving down a road, the car tends to drift to one
side of the road. To keep the car straight, you must keep
the steering wheel firmly in position. This problem creates
a dangerous condition and normally appears gradually. Slight
drifting to one side is often overlooked, and only severe
pulling is noticed.
The probable causes are:
1) All of the
car's tires do not have the same air pressure.
2) The wheels
are out of alignment.
3) One brake is dragging or isn't
releasing.
4) Loose steering parts and/or linkage.
5) The
car's tires are not worn evenly. |
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| Tyres are wearing more in the center than on the edges.
Why? |
Answer:You notice that the tires are very worn in the center of the tread, but the edges seem to
have plenty of tread left.
The probable causes are:
1) Tire pressures are too high.
2)
Tires have not been rotated frequently enough. |
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| Tyres wobble while driving. Why? |
Answer: As
you drive the car, you feel a shake through the steering
wheel from the tires. A slight wobble means a slight problem.
However, a serious wobble indicates a more serious problem.
Most of the time this problem starts out as a slight vibration
and progresses to a serious wobble.
The probable causes
are:
1) Tires need balancing.
2) Tires are worn.
3) The
wheel is bent or damaged.
4) The wheel lug nuts are loose.
5) There are worn or damaged steering parts. |
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| Wheel shimmy exists. Why? |
Answer:
You notice a side-to-side wobble in the steering wheel when
traveling at steady speeds. The vibration gets worse when
you are on an uneven road surface or after going over a
pot hole.
The probable causes are:
1) Your tires and wheels
are out of balance.
2) Your tires don't have the correct
pressure.
3) Your tires are worn.
4) A part of the steering
linkage is loose or damaged and needs to be replaced.
5)
You have worn suspension pieces. |
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| Car seems to bounce too much. Why? |
Answer: As you drive down the road and go over a bump, you feel the car continue to bounce up and
down well after the bump. Normally this problem will get progressively worse as you
continue to drive your car.
The probable causes are:
1) Your shock absorbers are worn.
2)
The mounts for your shock absorbers are broken.
3) Tyre pressure needs to be checked.
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