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 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

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