SS4- DIAGNOSING AND REPAIRING TIRES
Name_________________________
Description: During this lesson you will learn and become familiar with the automotive tire.
Diagnosis and service procedures such as how to properly change and balance tires and wheels
as well as, understanding abnormal tire wear patterns and what causes them. You will also
become familiar with TPMS (tire pressure monitoring systems) as well.
Reading Tire Information:
All vehicle tires have very important information printed on the side wall of the tire. This
information can tell you the speed rating, tire pressure specification, weather rating such as
snow or all-season, and also the tires thickness or plies. An example is below
A speed and load chart to help you identify your tires data
On 3 shop vehicle tires, locate and find the following information
Width of tire _____________________
Aspect Ratio ____________________
Diameter of wheel __________________
Load Rating ____________________
Speed Rating _________________________
Recommended Tire Pressure ________________
Tread wear rating ____________________
Width of tire _____________________
Aspect Ratio ____________________
Diameter of wheel __________________
Load Rating ____________________
Speed Rating _________________________
Recommended Tire Pressure ________________
Tread wear rating ____________________
Width of tire _____________________
Aspect Ratio ____________________
Diameter of wheel __________________
Load Rating ____________________
Speed Rating _________________________
Recommended Tire Pressure ________________
Tread wear rating ____________________
Identifying Tire Wear Patterns and Causes
Below are some tires that have worn abnormal. I want you to review these and
find three tires in the shop with wear on them. Identify each to the instructor
Tire #1 ___________________________________________
Tire #2 ___________________________________________
Tire #3 ___________________________________________
Instructor Ok ______________________________
Removing a tire from the wheel
Have instructor demonstrate how to remove a tire from the wheel
Now you will remove a tire and install one by yourself
Instructor OK ________________________________
Tire Balance
Tire balancing compensates for the weight of the tire and wheel assembly after the tire is
mounted. A wheel is out of balance when one area is heavier or lighter than the rest. The result?
Bouncing or wobbling, which can decrease treadwear, increase vibration and cause stress on
your vehicle. The cure? Correction weights are added to counterbalance the tires.
When to Balance
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A tire is replaced
A balance weight is moved or removed
You purchase new tires
How Wheels are Balanced
To balance a wheel, a balancing machine is used to determine where the heavy spots are.
Weights are then attached to the exterior or interior of the wheel to counteract centrifugal forces
acting on the heavy areas when the wheel is turning. This will eliminate vertical bouncing and
side-to-side wobble.
Static and Dynamic Unbalance
Have the instructor demonstrate how to balance a tire and wheel
Complete the procedure now by yourself
Instructor OK ______________________________
Rotating Tires
Rotating your tires as part of your regularly scheduled vehicle maintenance has many benefits.
It helps to maintain an even amount of treadwear on all 4 tires. That prolongs the life of your
tires, leads to improved gas mileage and a smoother more comfortable ride. Regularly rotating
your tires can also prolong the life of your vehicle’s suspension components by reducing
vibrations. Since you need to remove the wheels to rotate your tires, you get the opportunity to
look over the undercarriage components and catch any problems in the very early stages which
can save you money down the road. Also, many tire manufacturers require regular tire rotation
in order to keep the mileage warranty valid. A good rule of thumb is to rotate your tires at the
same intervals you get your oil changed whether your tires show uneven wear signs or not.
While this is a good recommendation, you should always follow the guidelines in your vehicle’s
owner manual for timing as well as the best rotation pattern for your vehicle and type of tires.
Locate a shop vehicle to perform a tire rotation on and complete the
tasks
Instructor OK ________________________________
Tire Pressure Monitoring Systems
Direct Monitoring Systems
Direct tire pressure monitoring systems measure, identify and warn the driver of low pressure.
Because direct systems have a sensor in each wheel, they generate accurate warnings and can
alert the driver instantly if the pressure in any one tire falls below a predetermined level due to
rapid air loss caused by a puncture. In addition, direct tire pressure monitoring systems can
detect gradual air loss over time. Some direct systems use dashboard displays that provide the
ability to check current tire pressures from the driver's seat.
Direct systems attach a pressure sensor/transmitter to the vehicle's wheel inside the tire's air
chamber. Most Original Equipment and some aftermarket systems attach their air pressure
sensor/transmitter to special tire valves. While the presence of a metal clamp-in valve typically
identifies the presence of a direct tire pressure monitoring system, special snap-in rubber valves
have also been used to support direct system sensors. The transmitter's signal is broadcast to the
in-car receiver and the information is displayed to the driver.
Some aftermarket and Original Equipment direct monitoring systems attach the
sensor/transmitter to the wheel with an adjustable metal strap. These sensors/transmitters and
their straps only weight a few ounces and allow virtually universal application on car and light
truck wheels. Since standard snap-in rubber valves are still used for these applications, it is
important that the owners of these systems let their tire installer know that the vehicle is
equipped with a direct system banded to the wheel before they change the tires.
Tire Rack works with wheel manufacturers to develop aftermarket wheels that accommodate
direct tire pressure monitoring sensors/transmitters. This results in our ability to offer a wider
selection of aftermarket alloy wheel styles that accept Original Equipment direct system
components. Additionally, the Tire Rack's fitment specialists have carefully determined which
aftermarket wheels will be compatible with the vehicle and system installed for customers
purchasing Tire & Wheel Packages or wheel upgrades. Search results include notes regarding
TPMS sensors and sensors can confidently be purchased online with wheels.
Indirect Monitoring Systems
In the interest of providing a lower cost Original Equipment system, indirect tire pressure
monitoring systems were developed by vehicle manufacturers wishing to comply with the law
while minimizing development time and cost. Indirect systems use the vehicle's antilock braking
system's wheel speed sensors to compare the rotational speed of one tire to that in another
position on the vehicle. If one tire is low on pressure, its circumference changes enough to roll at
a slightly different number of revolutions per mile than the other three tires. Reading the same
signal used to support ABS systems, the vehicle manufacturers have programmed another
function into the vehicle's onboard computer to warn the driver when a single tire is running at a
reduced inflation pressure compared to the others.
Unfortunately, indirect tire pressure monitoring systems have several shortcomings. Indirect
systems won't tell the drivers which tire is low on pressure, and won't warn the driver if all four
tires are losing pressure at the same rate (as occurs during the fall and winter months when
ambient temperatures get colder). Additionally, our current experience with indirect systems
indicates that they can generate frequent false warnings. We have found that false warnings may
occur when the tires spin on wet, icy and snow-covered roads. In these cases, the false alarms
would train the driver to disregard the tire pressure monitoring system's warnings, negating its
purpose completely.
Caution:
1. Before removing a tire from a TPMS equipped rim, be sure to take extra
care not to break the sensor inside the wheel, this is easily done, trust
me!!!!
2. TPMS may need to be re-learned or programmed after a tire rotation so
follow the manufacturer’s specifications for proper re-learn
ASE Questions:
1. Tire size information can be found on a sticker located on the driver’s door
called a __________________________
2. A tire speed rating of “H” would indicate ___________________________
3. In comparison of a “100”wear indexed tire to a “200” wear indexed tire, the
“200” load tire will last __________________ as long as the “100” wear tire
4. A _____________________ provides a means of installing or removing a
tire from the wheel.
5. Explain hub centric and lug centric wheels
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6. When checking a hot tire that calls for, “35 lbs of air” how much air should
be added or put into the tire.
7. Explain wheel tramp, the type of wear it causes, and what causes wheel
tramp.
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8. Slight indentations on a tire side wall are ______________________.
9. Some tires are designed to be run in ________________ direction.
10. Tire Runout can be either _________________ or __________________.
11. Out of round tires can be __________________ but will still cause
_____________________.
12. What is tire and wheel matching and why is it necessary sometimes?
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