1. Tire and Wheel Service
Chapter 62

2. Objectives Adjust tire pressures correctly for all cars Rotate tires
Repair tire punctures in the correct manner
Determine causes of tire-related vibration
Understand and perform tire balancing

3. Introduction Tire service is a large area of automobile repair
Average owner will replace at least one set of tires
Tire life defends on:
Tire quality
Air pressure
Vehicle weight
Driving conditions
Suspension condition
Wheel alignment

4. Tire Inflation Results of low tire pressure
Temperature of the tire rises
Load-carrying capacity of the tire is lowered
Tread life is reduced
Fuel consumption increases
Outside edge of tire wear excessively

5. Checking Air Pressure Vehicle owners should check air pressure
At least once a month
Considerations
Check when tires are cold
Use accurate air pressure gauge
Normally inflated radial tires have a bulging sidewall

6. Checking and Adjusting Tire Pressure
Important points
All valve stems should have screw caps
Use a high quality tire gauge
Tire pressure gauges are usually equipped with a pin to release air
Government has mandated the installation of tire pressure monitoring systems (TPMS) on all new vehicles manufactured since 2008
Typical tire loses one psi in pressure each month

7. Tire Wear Four psi decrease in pressure below recommended amount
Results in a 10% loss of tread life
Fastest tire wear occurs during hard cornering, braking, and acceleration
When tire wears within 1/16" of the bottom of its tread, wear bars become obvious
Scalloped or cupped wear is caused by tire hopping up and down on road
Inspect tire for physical damage

9. Sidewall Checks and Tire Rotation
Sidewall cracks
Caused by age and years of exposure
Slight sidewall indentation
Common characteristic of radial tires
RVs and light trucks with dual rear tires
Often have uneven wear on rear tires
Front wheels wear the most
Typical rotation for front-wheel-drive cars moves front tires to the rear on the same side

10. Removing and Tightening Lug Nuts
Important points
Removing lugs is easiest with impact wrench
Tighten evenly in a crisscross pattern
Lugs nuts for steel wheels and some aluminum are tapered
Anti-theft nuts are popular on custom wheels
Special type of lug nut is used with aluminum wheels

11. Repairing Wheel Studs When one or two threads are damaged
They can be cleaned up with a thread chaser
Broken lug bolts must be replaced

12. Removing and Mounting Tires on Rims
Important points
Tires can explode and fingers can be cut off if proper caution is not observed
Tire size and construction matches wheel rating
Rim diameter matches diameter on sidewall
Remove valve core to deflate tire completely
New tire changer design has emerged in response to needs
Beads must be unseated from the bead seats
Tire iron is used to remove the tire from wheel

13. Inspecting the Tire and Wheel and Valve Stem Service
After tire is removed: inspect inside for damage
Inspect wheel rim for damage
Rust can damage bead seat on a wheel
Valve stem service
Rubber valve stems are customarily replaced when new tires are installed
Can be replaced without removing tire
Be careful not to damage a direct-type TPMS
Do not force the tire over the sensor

14. Rubber Lubricant Advantages of rubber lubricant Directional tires
Reduces friction between tire beads and edge of rim during mounting
Helps seal around bead during initial inflation
Friction between bead seats and tire bead will be reduced when inflating
Directional tires
Designed to be run in only one direction
Indicated with an arrow

15. Install the Tire Major steps and considerations
Clamp wheel to tire changer
Install inside bead
Inflate the tire
Seat the beads
Tubeless tires require a substantial volume of airflow for beads to start to seat on rim
Most tire machines have an inflation chamber and an in-line dial indicator-type tire gauge
Custom rims should be clamped from the outside

16. Mounting High-Performance Tires
Vehicle can have many thousands of dollars invested in its tires and wheels
Aftermarket wheels: $100 and $1,500 each
Speed-rated tires: $600 or more each
Servicing high-performance tires with tighter tire beads results in tear to bead or sidewall
Low-profile tires are more apt to suffer bead damage during removal of rim
Always apply rubber lubricant

17. Bead Roller Tire Changer
Developed for use with high-performance wheels
Tulip clamping system uses pads protected by rubber
Removing a tire is similar to the rim clamp type
Except bead is automatically pushed into drop center while bead lever tool pulls bead over rim edge
Valve core should not extend above top of valve stem

18. Tire Runout
When a tire is not correctly mounted on a rim or is out-of-round it will have runout
Another possible is a out-of-round blemished tire
Runout can be checked with a dial indicator

19. Tire Repair Important points
Full water tank is used to check for leaks
Mark the location of leak
Inspecting tire: remove it from wheel
Tire must be dry prior to inspection
Check tire outside and inside

20. Repairing a Tire
Puncture repairs can be done with a rubber tire plug and a patch
Repairs can be made within tread area
Opinions differ as to repairability of some tires

21. Preparing the Tire for Repair
Important points
Inside of tire liner must be cleaned
Steel-belted radials should be plugged and patched
Hole must be drilled or reamed first
Rubber plug is inserted into the hole with vulcanizing cement
Liner is lightly buffed

22. Patching the Tire Major steps
After cleaned area dries: apply an even amount of vulcanizing cement to buffed area
Remove adhesive covering and center patch over hole
Roll patch into place
Some plugs are a combination of plug and patch
Used when the hole goes straight into the tire
Liquid puncture sealants
Not recommended

23. Tire and Wheel Balance
Tire imbalance is one of several causes of vehicle vibration
Wheel weights are attached to the rim to correct imbalance
Several types of clip-on weights are available
Lead was banned for use in wheel weights
Substantial number of wheel weights fall off vehicles

24. Types of Wheel Balance and Couple Imbalance
Wheel balancing methods: static and dynamic
Static imbalance subjects wheel to vertical impacts that become worse with higher speed
Couple imbalance
Tire is lopsided
Usually imbalance on both sides of the tire
Wheel may be in static balance but not couple balance

26. Dynamic Balance and Computer Balancers
Combination of static and couple imbalance
Dynamic wheel balancers spin the wheel and locates vibration sources
Computer balancers
Very popular and easy to use
Balance both the static and dynamic planes
Tire that is dynamically balanced will also be statically balanced

27. Centering the Wheel on the Balancer
Wheel not properly installed on wheel balancer
Causes imbalance
Major steps and considerations
Center wheel with manufacturer method
Backing plate and wheel lug flange must be clean and undamaged
Hub-centric steel wheel: use a centering cone
Lug-centric wheels: use lug-centering adapter
Program wheel balancer after mounting

28. Match Mounting and Force Variation
Some balancers match a tire's imbalance to a wheel's imbalance
Computer determines amount the wheel and tire are out of balance
Force variation
Load is placed against tire: stiffness of sidewall and tire's footprint change
Some come with a mark or paint dot on sidewall
Some tire balancers can measure force variation

29. Installing the Wheel Major steps and considerations
Before installing: double-check to see bolt holes in wheel are in good condition
Finger-tighten lug nuts
Shake wheel to center it
Cross-tighten lug nuts with a torque wrench
Some shops use a torque stick or torque socket to initially tighten wheel lugs using an impact wrench

30. Tire Pressure Monitoring System Service
When tires are rotated or a defective sensor is replaced
Some TPMS require the computer to be reprogrammed
Different types of TPMS measuring/resetting tools
TPMS sensor
Replaced if it fails mechanically or electrically
Special procedures are followed
Tire pressure monitors
Installed on vehicles that did not have them as OE