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? Today we are going to be talking about the basic of tire construction and a few basic about the theory of the tire. we will be looking at what a tire is made of because we know that it can just be rubber because it is black. So we will actually show you what percent of a tire actually is rubber and is it really black because it is made of rubber.

Actual components that go into a tire. Raw Rubber Steel Nylon Polyester Rayon Carbon Black Synthetic Rubber Fiberglass Aramid Brass Most people think tires are made mostly of rubber. This is far from the truth at all . A tire consist of many different things such as steel. nylon, polyester, rayon, carbon black, synthetic rubber(which is man made rubber), fiberglass which is light weight but add strength, aramid, brass. All these things help add strength, heat distribution, lower the actually weight of the tire, also help protect it from natural weathering (sun, wind, rain, snow). 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. Yes it is true by volume it may seem that all a tire is made of is rubber. when you actually look at the comparison of weight and components you can see that the actually weight of the tire is only 30% can be blamed on rubber, the rest lies on many of the other components. When you actually look at it you can see why they use so much rubber. The weight factor is actually quite unbelievable when you look at it.

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. John was a Scotsman who experimented with covering a rubber tube with canvas to improve the ride comfort of his sons tricycle. After weeks of work the first pneumatic tire came up to its first competitive challenge. On February 28 1888 When rolled across a courtyard, solid tires choked halfway through, but Dunlop’s “MUMMY” tire didn't stop until it crashed into a door.

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. Competitive absorbers work by capturing and absorbing harmful UV light wane Energy. All tire manufacturers use the same competitive absorber, carbon black. This is why tires are black and why tires are not available in designer colors. All UV stabilizers are sacrificial, meaning the are gradually “used up” to where they can no longer protect against UV damage. As carbon black loses the ability to do its job, it turns gray. This is why rubber grays as it ages. OTHER DEGRADENTS Silicone oils can remove the protective waxes and increase the rate of degradation. Common automotive “protectants” and “tire dressings” are typically devoid of UV stabilizers of any type and contain Petrochemicals and/or silicone oils which dissolve away the protective waxes and can actually aggress the sidewall. In the event of warranty sidewall failure, one of the first things tire manufacturers like for is evidence of the use of these types of products. In turn this will void warranty.

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. Has plies running at an angle from bead to bead. The cord angle is also reversed from ply to ply. The tread is bonded directly to the top ply. A bias ply tire is one of the oldest designs and it does NOT use belts. the position of the cords in a bias ply tire allows the body of the tire to flex easily. This tends to improve cushioning action. A bias ply tire provides a very smooth ride on rough roads. One disadvantage is that The weakness of the plies and tread reduce traction at high speeds and increase rolling resistance.

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. Is a bias tire with belts added to increase tread stiffness. The plies and belts normally run at different angles. The belts do NOT run around to the sidewalls but only lie under the tread area. Usually, two stabilizer belts and two or more plies are used to increase tire performance. A belted bias tire provides a smooth ride, good traction, and offers some improvement in tolling resistance over a bias ply tire.

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 Has plies running straight across from bead to bead with stabilizer belts directly beneath the tread. A radial tire has a very flexible sidewall, but a stiff tread. The belts can be made of steel, Flexten, fiberglass, or other materials. Radial tires have a very stable footprint (shape and amount of tread touching road surface). This improves safety, cornering, braking, and wear. One possible disadvantage of a radial tire is that it may produce a harder ride at low speeds. The stiff tread area doesn't give or flex as much on rough roads.

Tire Cutaway

Tire Cutaway

Cooper Tire Cutaway

Tire Cutaway

Tire Sidewall

Tire Sidewall

Tire Sidewall

Tire Size LT = Light Truck

How Old is your Tire?? Here's how to read the date code on tires; for example, the last 4 digits (4301) means the tire was manufactured in the 43rd week of 2001. The tire's manufacturing date is imbedded in the tires’ identification Number.

How Old is your Tire?? This one is 3808, means the tire was manufactured in the 38th week of 2008. For older tires with 3 digits search the internet on the codes.

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.

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

Load Index For a complete listing of load index ratings go to this web site

Load Index

Speed Rating Chart Note: The speed rating relates only to tire speed capacity, and is NOT a recommendation to exceed posted speed limits; always drive within the legal speed limits.

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

TEMPERATURE: Ability to withstand extreme heat - A, B, C 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 Placard 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 Competition Passenger Touring Performance Snow Rain All Season                                                                             Performance Grand Touring High Performance Passenger

Net to Gross Ratio – The amount of rubber hitting the road.                                                                                                                       

35 psi sitting still in water Effects of Tire pressure and Speed on wet traction 35 psi at 60 mph 30 psi at 60 mph 25 psi at 60 mph

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 Defects

Bulge

Tire Defects

Chunk Outs

Tire Defects

Cracks

Foreign Objects

Tire Wear Side Wear & Feathering

Tire Wear

Cupping

Tire Wear

Tire Wear

Tire Wear

Tire Pull Defective/damaged tires Bent wheel (rim) Excessive shoulder wear Excessive feathering

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

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!

(Roll your mouse across the pictures to confirm you were right) Tire Pressure Quiz 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.                                                                                  (Roll your mouse across the pictures to confirm you were right) 29 psi cold 20 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 http://tireguides.com/default.asp Tire Guides Inc Good heart - Wilcox                                                      

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