1. Chapter 66
Tire, Wheel, and
Wheel Bearing
Service

2. Contents Tire, wheel, and wheel bearing diagnosis
Wheel cover removal and installation
Tire maintenance
Measuring tire and wheel runout
Wheel balance
Mounting and dismounting tires
Tire puncture repair
Wheel bearing service

3. Tire, Wheel, and Wheel Bearing Diagnosis
Problems usually show up as vibrations, abnormal tread wear patterns, steering wheel pull, abnormal noises, and other symptoms

4. Diagnosing Tire Problems
Inspect the tires for problems
Check both sidewalls and the tread area
If necessary, road test the vehicle to verify the customer complaint
Make sure the symptoms are not being caused by steering, suspension, or front wheel alignment problems

5. Wiggle the tire to check for dry, rough, or loose wheel bearings
Inspecting the Tires
Wiggle the tire to check for dry, rough, or loose wheel bearings

6. Typical damage found on used tires
Tire Impact Damage
Typical damage found on used tires

7. Tire Wear Patterns

8. Tire Inflation Problems
Correct tire inflation is important to the service life of a tire
assures the full tire tread contacts the road
Most tires have a recommended cold inflation pressure of 1 to 3 pounds-per-square inch (psi) below the maximum listed air pressure.
Under inflation
wears the outer edges of the tread
sidewalls flex, building up heat
Overinflation
wears the center of the tread
produces a rough ride

9. Tire Inflation Pressure

10. Load Index
Load index indicates the maximum load capacity each tire is designed to support. Like speed ratings, assume near perfect operating conditions to obtain the ratings listed in the table on the left.

11. Tire Vibration Problems
When one of the front tires is vibrating, it may be felt in the steering wheel
When one of the rear tires is vibrating, it will be felt in the center and rear of the car

12. Causes of Tire Vibration

13. Tire Noise Thumping sound caused by ply separation
Whine due to abnormal tread wear
When these noises occur, inspect the tire for an out-of-round condition or tread cupping
these conditions require replacement

14. Wheel Bearing Noise Produced by a dry, worn wheel bearing
When balls or rollers are damaged from lack of lubrication, they may emit a humming or growling sound
Checking the bearings:
raise the vehicle on a lift
rotate the tire by hand
feel and listen for bearing roughness
wiggle the tire to check for looseness

15. Removal and Installation
Wheel Cover
Removal and Installation

16. Pry between the wheel and cover at four alternating points
Wheel Cover Removal
Pry between the wheel and cover at four alternating points

17. Wheel Cover Installation
Hold the wheel cover in place with the valve stem sticking through the cover

18. Tire Maintenance
Maintenance procedures include periodic inspection, inflation pressure checks, and tire rotation
These maintenance steps help ensure safety and longer tire life

19. Checking Tire Inflation Pressure
Remove the valve stem cap
Press the tire gauge squarely over the stem
Compare the reading to the maximum pressure printed on the tire’s sidewall or in the operator’s manual
Adjust the pressure as necessary
Reinstall the cap

20. Tire Service Tools

21. Rotating Tires Ensures maximum tire life
The front and rear tires wear differently
Rotation helps even out tire wear
Tires are rotated at specific intervals, such as every 3000 miles (4827 km)

22. Tire Rotation Patterns
BIAS TIRES RADIAL TIRES

23. Torquing Lug Nuts
Torque is very important, especially on vehicles with mag wheels and lightweight hubs
Overtorquing can cause wheel and hub distortion or brake pulsation
Undertorquing might allow the lug nuts to loosen and the wheel to fall off

24. Torque the nuts to specifications in a crisscross pattern
Torquing Lug Nuts
Torque the nuts to specifications in a crisscross pattern

25. Measuring Tire and Wheel Runout Tire runout Wheel runout
caused by ply separation or manufacturing defect
Wheel runout
caused by impact damage or incorrect welding of the spider and rim

26. Lateral Runout Side-to-side movement of a wheel or tire
Maximum for a tire
0.090" (2.0 mm)
Maximum for a wheel
0.045" (1.0 mm)

27. Measuring Lateral Runout
Mount a dial indicator with the stem against the sidewall and side of the rim
Check the reading at several points

28. Radial Runout
Difference in radius from the center axis of rotation (out-of-round)
Maximum for a tire
0.060" (1.5 mm)
Maximum for a wheel
0.035" (0.9 mm)

29. Measuring Radial Runout
Mount a dial indicator with the stem against the tread and the lip of the rim
Check the reading at several points

30. Wheel Balance
Improper wheel balance is a common cause of tire and steering wheel vibration
When one side of a tire is heavier than the other, centrifugal force tries to throw the heavy side outward when the tire is rotating

31. Caused by a heavy spot located in the center of the tire tread
Static Imbalance
Caused by a heavy spot located in the center of the tire tread

32. The heavy spot is to one side of the tread or on the sidewall
Dynamic Imbalance
The heavy spot is to one side of the tread or on the sidewall

33. Wheel Balancing Wheels are balanced by adding wheel weights
Most weights are press-fit onto the wheel
Weights for some mag wheels stick onto the wheel with an adhesive backing

34. Wheel Balancing Static balancing Dynamic balancing
add weights opposite the heavy area of the wheel
if a large amount is needed, add half to the inside and half to the outside of the wheel
Dynamic balancing
add weights exactly where needed
the dynamic balancing machine will indicate where weight must be added

35. Wheel Balancing

36. On-Car Balancing Follow the equipment operating instructions
Wear eye protection
Remove rocks and debris from the tread
Place the vehicle on a jack stand
When using the engine to spin the drive wheels, do not exceed 35 mph (40 to 56 km/h)
when one wheel is on the floor, the free wheel will turn at twice the indicated speed

37. With a limited-slip differential, raise both rear wheels off the floor
On-Car Balancing
With a limited-slip differential, raise both rear wheels off the floor

38. Wheel Balancers
A wheel balancing machine is used to determine which part of a wheel assembly is heavy
Bubble balancer
static balance
Off-car balancer
static or dynamic balance
On-car balancer

39. The wheel and tire assembly is mounted on the machine
Bubble Balancer
The wheel and tire assembly is mounted on the machine

40. Add weights until the bubble is centered
Bubble Balancer
Add weights until the bubble is centered

41. Off-Car Balancer
The wheel and tire assembly is mounted on the machine and rotated
The machine will indicate where weights should be added
After adding weights, spin the tire again to check for vibration

42. Off-Car Balancer

43. On-Car Balancer
Provides an electric motor to spin the wheel and tire assembly
An electronic pick-up unit or a hand-operated device is used to determine where weights are needed
Balances the wheel cover, brake disc, and lug nuts, along with the tire and wheel

44. Mounting and Dismounting Tires
A tire changing machine is used to force the tire on and off the wheel
prevents tire or rim damage
reduces the labor required

45. Power head turns the bar to force the beads over the rim
Tire Changing Machine
Power head turns the bar to force the beads over the rim

46. Applies tremendous force to stretch the tire bead on and off the wheel
Tire Changing Machine
Applies tremendous force to stretch the tire bead on and off the wheel

47. Safe Work Practices Wear eye protection
Keep your fingers out of the way
Never mount a tire on a rim that is not smooth and clean
Always lubricate the bead and wheel flange with the proper lubricant
Only inflate a tire on the machine or in a safety cage, as recommended

48. Safe Work Practices
Stand away from the tire when adding air; a loud “pop” sound will indicate when the beads seat
Do not exceed 40 psi (276–345 kPa) when initially inflating a tire
After inflation, install the core and inflate the tire to the recommended pressure

49. Finding/Repairing a Leak
Inflate the tire with air
Place the tire in a drum of water, or wet the tire with a water hose
Look for air bubbles forming on the tire or around the bead at the rim
Bubbles indicate leakage
Mark the leak with a crayon or chalk
Puncture must be in the tread to be repairable
There must be adequate tread left on the tire to be repairable
Punctures through the tread can be repaired with a plug if they are not too large, but punctures to the sidewall should not be repaired.

50. Wheel Bearing Service Wheel bearings are normally filled with grease
Modern Vehicles usually do not have serviceable wheel bearings
If the grease dries out, the bearing will fail
Some bearings on older vehicles are serviceable
Most newer bearings are sealed units
Wheel bearings on front-wheel –drive vehicles are difficult to service and require special methods or tools.

51. Nondriving Hub and Tapered Roller Wheel Bearing Assembly

52. Wash and dry the bearings
Bearing Inspection
Wash and dry the bearings

53. Bearing and race problems
Bearing Inspection
Bearing and race problems

54. Greasing the Bearings
Serviceable disc-brake wheel bearings require a special grease called high-temperature wheel-bearing grease
Use a packer or grease the bearing assemblies by hand
Make sure the grease is worked completely through each bearing cage and around every ball or roller

55. Greasing the Bearings

56. Driving Hub and Wheel Bearing Assembly

57. Rear Hub Assembly (Non-serviceable)
If bearings are dry and noisy, remove and replace the entire assembly