tire tech 101 - eng.sut.ac.theng.sut.ac.th/me/2014/document/advanautotech/csd_2_wheel_tire… ·...
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Tire Tech 101 What is a tire made of.
What percent of a tire is
rubber?
What is a pneumatic
tire?
What is the difference
between radial & bias
ply tires ?
Why are tires black?
Actual components
that go into a tire.
Raw Rubber
Steel
Nylon
Polyester
Rayon
Carbon Black
Synthetic Rubber
Fiberglass
Aramid
Brass
Aramid: A synthetic fabric used in
some tires that is (pound-for-pound)
stronger than steel.
What percent of a tire is
rubber? By weight, give or
take 30%
By volume, quite a
bite more.
Tire compontents
Rubber
Steel Nylon
RayonCarbon Black
Synthetic Rubber
0
10
20
30
What Is Pneumatic Tire?
Filled by air,
especially compressed
air: a pneumatic tire
(dictionary definition).
All tires manufactured
today are considered
Pneumatic tires.
Who Invented The First Tire?
It was invented in
1888, by John Dunlop.
This would be the end
of the solid tire.
Why are Tires Black?
To protect the rubber
from the harmful UV
rays.
A common type of UV
stabilizer called a
competitive absorber is
added to capture and
absorb these harmful
UV light wave energy.
Bias Ply Tire
A bias ply tire has
plies running at an
angle from bead to
bead.
The cord angle is also
reversed from ply to
ply.
Tread is bonded
directly to the top ply.
Belted Bias Tire
Is a bias tire with belts
added to increase tread
stiffness.
These belts are also
ran at a different
angle.
These belts only lie on
the tread area and not
on the side walls, like
cords.
Radial Ply Tire
Has plies running straight
across from bead to bead
with stabilizer belts lying
directly beneath the tread.
This results in the radial
having flexible side wall,
but a stiff tread.
Michelin developed it in
1955! 50 years ago!
– Sears imported them in the
1970s
Tire Cutaway
Tire Cutaway
Cooper Tire Cutaway
Tire Cutaway
Tire Sidewall
Tire Sidewall
Tire Size
LT = Light Truck
Tire Size
If you switch tire size on a car you can mess up the
speedometer to figure out how close you are do the math
to figure out the diameter.
For a 205/75R15 tire it would look like this
205 X .75 x 2 ÷ 25.4 + 15= 27.106
Tire size X Aspect ratio X 2 ÷ 25.4 + Rim size
100
Aspect Ratio
Percentage of tires height in relation to it’s width
A 60 series tire height will be 60% of the width.
The aspect ratio can be a 40,50, 60,65,70,75,78
These are some of the most common ones.
Aspect Ratio
So if we have a P205/60R15 tire. The width is
205 millimeters and the height is 60% of the
width. That means 205 x .6 = 123 millimeters.
That tire should be 123 millimeters tall.
You can raise or lower your car by changing the
height of the side wall.
SERVICE DESCRIPTION
On most tires, you will notice some additional numbers and letters
located at the end of the tire size.
For Example:
P185/70R14 92S
In this example the 92S is called the SERVICE DESCRIPTION.
The Service Description consists of two parts, LOAD INDEX (the
numbers) and SPEED RATING(the letter).
The SPEED RATING is a letter which designates the rating
achieved on indoor wheel testing.
Load Index
The LOAD INDEX is a number ranging from 0 to 279 and covers
load capacities from the smallest motorcycle tires to those for the
largest earth mover tires. In passenger car tires, the load index
typically ranges from 75 to 100.
As in aspect ratio where the operative word was ratio, in load
index the operative word here is index. An index is a point of
reference or a chart to refer to find information. All tire guides
used by retail tire stores have them and they have load index charts
in them. By referring to the load index chart in the Tire Guide you
can determine the maximum load carrying capacity of a tire size
from using the load index number at the end of the P-Metric size.
For Example:
Load Index Max Load (lbs.)
91 1356
92 1389
93 1433
Load Index
For a complete listing of
load index ratings go to this
web site
Load Index
Speed Rating
from Michelin Tyres 2003
Speed Rating
Thanks
To
Tire
Guides.
Com
Effects of speed on a tire
Tires are tested under Laboratory conditions they are not worn
out, are properly inflated, not over loaded, damaged or altered.
Just because the tire is rated at these speeds does not mean the
car is safe or legal to drive at those speeds.
TIRE GRADING
Uniform Tire Quality Grading System Code UTQGS
TREAD WEAR: Tire life expectations
100 is base line, 150 will give you 50% more wear then one ranked
100 (100 = 30,000 miles
TRACTION:Braking capabilities – AA, A, B, C
(AA Highest rating)
Traction Grades Asphalt g Force Concrete g Force
AA Above .54 .41
A Above .47 .35
B Above .38 .26
C Less than .38 .26
TIRE GRADING
TEMPERATURE: Ability to withstand extreme heat
- A, B, C
Tire pressure Tire pressure should be check monthly
Tire pressure should be checked cold
For every 10° Fahrenheit change in air temperature, your tire's inflation pressure will change by about 1 psi
The air pressure in the tire supports the car, make sure that it is the right amount.
If you check the air pressure inside the shop at a temperature of 70° will the tires be the right pressure when it goes outside at 0°?
Tire Pressure The EPA says your mileage drops 1% for
every 2 pounds under the recommended tire
pressure.
Tire pressure Use the tire pressure recommended in your vehicle's
owner's manual or tire information placard
Tire Placard
Driver’s door pillar
Glove box door or Center Consol lid
Trunk lid or Gas door
Tire pressure
This is the Maximum pressure for the tire not the
normal pressure, use only if car is fully loaded.
Thanks to Michelin for the picture
Tread Patterns
Passenger
Touring
Performance
Snow
Rain
All Season
Grand
Touring
Performance
Passenger
Competition
High Performance
Net to Gross Ratio – The amount of rubber hitting the road.
35 psi sitting still in water
35 psi at 60 mph
30 psi at 60 mph
25 psi at 60 mph
Effects of Tire pressure
and Speed on wet
traction
Nitrogen in tires
Nitrogen is a dry inert gas. That means
moisture free.
Nitrogen leaks out of the sidewall three
times slower then oxygen.
Oxygen oxidizes the rubber in the sidewall.
Plus the moisture in the air will rust the
steel rims.
Effects of tire pressure
Over inflation
Wide tires that are under inflated can also wear in the center
Effects of tire pressure
Under inflation
Tire Defects
Separations
Bulges
sidewall separations
tread tearing,
chunking
shoulder cracking
Sidewall cracking
Weather cracking
Breaks in sidewall/tread
Excessive radial runout
– diameter
Excessive lateral runout
– width
Conicity
– not level across tread
cone shaped
Tire Wear
Cupping
Tire Defects
Bulge
Tire Defects
Chunk Outs
Tire Defects
Cracks
Tire Defects, Foreign Objects
Tire Wear
Side Wear & Feathering
Tire Pull Defective/damaged tires
Bent wheel (rim)
Excessive shoulder wear
Excessive feathering
Tire Defects
Tire Wear
Tire Wear
Tire Wear
Tire Rotation
Tires should be rotated between 5,000 and 7,500
miles see charts on how to rotate
Thanks to Michelin for the picture
Tire Rotation
Effects of Mismatched Tires
Different Manufactures
Different sizes
New and/or used tires
Effects on speedometer
Effects on ABS/Traction Control Systems
Effects on vehicle handling
Tire Replacement One problem with replacing just one tire on FWD,
AWD or 4X4’s is that you have a different size tire
when you measure the circumference this creates a
problems with the transaxles and drive trains. It
also cause’s problems with traction control and
ABS stopping. Tires need to be rotated at least
every 7500 miles and if one tire is damaged on one
of these cars all 4, count them FOUR tires need to
be changed. Tread depth should be maintained
within 4/32 of each tire.
For more info go to
Wheels
steel \ cast
Off set
Bump steer
Scrub Radius
– note pages C 311- 313
How to measure a rim
You need to measure from bead seat to bead seat. But you
cannot measure from the inside with a tape measure take
a good guess where it is on the outside. This one is 14 inch’s.
How to measure a rim
To find the diameter you measure the circumference (C) and divide
it by Pi (3.14) ( C ÷ Pi = Diameter )
44 ÷ 3.14 = 14.0127 So it is really a 14 inch rim
That math class is important.
Wheel Balance Improper balance causes the tire to vibrate
several types of balancers, Bubble balancers,
on car balancers and off car balancers shown.
Some are hand spun and some are powered
Static balance
C 77
Equals wheel tramp or hop
weight not even around the
tire must add weight to
other side to equal it out.
Dynamic balance
C- 78
equals wobble
side to side weights
not equal
Wheel Balance
Make sure when you balance a tire to use the right
adapter some wheels are Hub centric or lug centric that
means does it center on the Hub or the lugs most cars
from the factory are Hub centric but some after marker
wheels are lug centric
If you think that your balancer is not working right or
the wheel is off check the balance rotate it 180 degrees
and rebalance it. It should have the same readings.
Wheel Balance
Hub centric or cone adapter
lug centric
Air Pressure Monitors
May have a sensor
inside tire
May have a sensor in
the tire valve stem!
Sensors may have to
be recalibrated after a
tire rotation!
Tire Pressure Quiz
(Roll your mouse across the pictures to confirm you were right)
Can you easily identify which tire is 30% under inflated with your
eyes? Here is what they would look like in the morning as you
walked to your car in the garage.
20 psi cold 29 psi cold
Tire Pressure Monitoring Warns of significant lose of tire pressure
First used on 1994 Corvette
All cars & LD Trucks must have TP system by
2008
Two types: Direct and Indirect
Direct TP Warning System
Computer controlled (BCM) w/ radio
transmitters in wheels (pressure sensors)
Transmits actual TP of each tire
Displays on IPC
Diagnostic capabilities
Indirect TP Warning System ABS based system, using existing ABS hardware, w/
software modifications
Changes in TP affect tire circumference, affecting tire
speed
Sensors monitor each wheels speed, compares to one
another
Approx. 7 psi difference to trigger warning
Tire Pressure Monitoring
Before you do any work on these cars, make sure that
the warning lights are off before you work on the car.
If you mount or dismount the tire and it was not
working right before, you could be blamed for causing
a problem.
You need to do this with all cars and with all warning
lights such as, check engine & ABS etc.
Run Flat Tires
Run Flat Tires
Temp. supports
weight of vehicle
with no air pressure
Internal support,
thicker side walls,
stronger beads.
Can maintain
Mobility for 50 miles
up to 55 mph
Run Flat Tires Michelin unveiled the “Tweel” at the 2005 North
American International Auto Show
Increased mobility, lateral stability, and gas mileage
For more information go to A big thanks goes to these companies for use
of pictures and information
Good heart - Wilcox
http://tireguides.com/default.asp Tire Guides Inc
The End ??????
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