1. CHAPTER 5 Tire and Wheel Service

2. Discuss proper tire mounting procedures.
OBJECTIVES
After studying Chapter 5, the reader will be able to:
Prepare for ASE Suspension and Steering (A4) certification test content area “E” (Wheel and Tire Diagnosis and Repair).
Discuss proper tire mounting procedures.
Describe recommended tire rotation methods.
Discuss how to properly balance a tire.
Describe tire repair procedures.
Explain wheel and tire safety precautions.

3. KEY TERMS Dynamic balance Lateral runout Match mounting Modified X
Radial force variation
Radial runout
Shimmy
Static balance
Tire rotation
Tramp
Wheel mounting torque

4. INTRODUCTION
Proper tire service is extremely important for the safe operation of any vehicle.
Premature wear can often be avoided by checking and performing routine service, such as frequent rotation and monthly inflation checks.
Avoid overloading the vehicle and have any leaks repaired as soon as possible.

5. INTRODUCTION
FIGURE 5–1 Using soapy water from a spray bottle is an easy method to find the location of an air leak from a tire.

6. TIRE INFLATION
Tires should always be inflated to the pressure indicated on the driver’s door or pillar sticker.
Tires should be checked when cold, before the vehicle has been driven, because driving on tires increases the temperature and therefore the pressure of the tires.

7. Proper tire inflation is important for the following reasons:
Inflation pressure carries the load of the vehicle
Inflation pressure varies with temperature
Tire inflation affects fuel economy
Tire inflation affects tire life
The TREAD Act specifies that the driver be notified if the inflation of a tire drops by 25%.

8. TIRE INFLATION
FIGURE 5–2 This chart shows the relationship between tire inflation pressure and load capacity of the tire.

9. TIRE INFLATION
FIGURE 5–3 This chart shows that a drop in inflation pressure has a major effect on fuel economy.

10. TIRE INFLATION
FIGURE 5–4 Notice that if a tire is underinflated by 10 PSI, the life expectancy is reduced by 40%.

11. What Is a “Temporary Mobility Kit”?
A temporary mobility kit is a system to inflate a flat tire supplied by the vehicle manufacturer instead of a spare tire. A temporary mobility kit can include:
A compressor powered by the cigarette lighter with stop leak.
An aerosol spray can that provides inflation and sealer.

12. What Is a “Temporary Mobility Kit”?
FIGURE 5–5 A temporary inflation pump that uses 12 volts from the cigarette lighter to inflate the tire.

13. What Is a “Temporary Mobility Kit”?
FIGURE 5–6 Many vehicle manufacturers include an aerosol can of sealer on vehicles that are not equipped with a conventional spare tire.

14. NITROGEN INFLATION
Some shops recommend and inflate tires using nitrogen instead of using compressed air.
Compressed air contains about 78% nitrogen, 21% oxygen, and 1% other gases.
If air already contains mostly nitrogen, why use pure nitrogen?

15. NITROGEN INFLATION There are several reasons, including:
The nitrogen molecule is slightly larger than the oxygen molecule so the tire will lose pressure faster if air is used instead of nitrogen.
Compressed nitrogen contains less moisture than compressed air. When the tire heats up, moisture in the tire vaporizes and expands, causing the pressure inside the tire to increase.
Race teams use nitrogen because they already come to the track with a cylinder of nitrogen to power the air tools.
Race teams also have more control over how much the pressure will increase when the tires heat up, because nitrogen has less tendency to change pressure with temperature change.
Some oxygen in the tires could, over a long period of time, cause the oxidation of the inner liner of the tire and the corrosion of the wheel.

16. NITROGEN INFLATION
FIGURE 5–7 Most shops that use nitrogen inflation install a green tire value cap to let others know that nitrogen, rather than air has been used to inflate the tire.

17. TIRE MOUNTING RECOMMENDATIONS
When removing a wheel from a vehicle for service, mark the location of the wheel and lug stud to ensure that the wheel can be replaced in exactly the same location.
Make certain that the wheel has a good, clean metal-to-metal contact with the brake drum or rotor.
Always check the rim size.
Install the tire-pressure monitoring system
Many tires have been marked with a paint dot or sticker. The tire should be mounted to the rim with this mark lined up with the valve stem.

18. TIRE MOUNTING RECOMMENDATIONS
Never use more than 40 PSI (275 kPa) to seat a tire bead.
Rim flanges must be free of rust, dirt, scale, or loose or flaked rubber build-up prior to mounting the tire.
When mounting new tires, do not use silicone lubricant on the tire bead. Use special lubricant such as rendered (odorless) animal fat or rubber lubricant to help prevent tire rotation on the rim.

19. TIRE MOUNTING RECOMMENDATIONS
FIGURE 5–8 Note the difference in the shape of the rim contour of the 16-in. and 16 1/2-in. diameter wheels. While it is possible to mount a 16-in. tire on a 16 1/2-in. rim; it cannot be inflated enough to seat against the rim flange. If an attempt is made to seat the tire bead by over-inflating (over 40 PSI), the tire bead can break, resulting in an explosive force that could cause serious injury or death.

20. TIRE MOUNTING RECOMMENDATIONS
FIGURE 5–9 When installing a tire-pressure monitoring system sensor, be sure that the flat part of the sensor is parallel to the center section of the rim.

21. TIRE MOUNTING RECOMMENDATIONS
FIGURE 5–10 This tire on a new vehicle has been match mounted at the factory. The yellow sticker is placed at the largest diameter of the tire. The valve core hole in the wheel is usually drilled at the smallest diameter of the wheel. The best way to make sure the assembly is as round as possible and to reduce the number of wheel weights needed to balance the tire is to align the sticker with the valve core.

22. TIRE MOUNTING RECOMMENDATIONS
FIGURE 5–11 (a) Cleaning the bead area of an aluminum (alloy) wheel using a handheld wire brush. The technician is using the tire changer itself to rotate the wheel as the brush is used to remove any remnants of the old tire. (b) Using an electric or airpowered wire brush speeds the process, but care should be exercised not to remove any of the aluminum itself. (Remember, steel is harder than aluminum and a steel wire brush could cause recesses to be worn into the aluminum wheel, which would prevent the tire from proper seating in the bead area.) The bead seat area on steel wheels should also be cleaned to prevent air leaks at the rim.

23. TIRE MOUNTING RECOMMENDATIONS
FIGURE 5–12 Rendered (odorless) animal fat is recommended by some manufacturers of tire changing equipment for use as a rubber lubricant.

24. Spin the Tires
When performing a vehicle inspection and the vehicle has been hoisted on a frame-type lift, check the tires by rotating them by hand. The tires on the nondrive wheels should spin freely.
On front-wheel-drive vehicles, rear wheels should rotate easily.
On rear-wheel-drive vehicles, front wheels should rotate easily.
On all-wheel-drive vehicles, all four wheels may require effort to rotate.

25. WHEEL MOUNTING TORQUE
For wheel mounting torque, make certain that the wheel studs are clean and dry, and torqued to the manufacturer’s specifications.
Always tighten lug nuts gradually in the proper sequence—star pattern (tighten one nut, skip one, and tighten the next nut).
This helps prevent warping the brake drums or rotors, or bending a wheel.

26. WHEEL MOUNTING TORQUE
FIGURE 5–13 Always tighten wheel lug nuts (or studs) in a star pattern to ensure even pressure on the axle flange, brake rotors or drums, and the wheel itself.

27. WHEEL MOUNTING TORQUE

28. Fine-Tune Handling with Tire-Pressure Changes
The handling of a vehicle can be changed by changing tire pressures between the front and rear tires.
Understeer
Oversteer

29. WHEEL MOUNTING TORQUE
FIGURE 5–14 Most manufacturers recommend using hand tools rather than an air impact wrench to remove and install lock-type lug nuts to prevent damage. If either the key or the nut is damaged, the nut may be very difficult to remove.

30. WHEEL MOUNTING TORQUE
FIGURE 5–15 A torque-limiting adapter for use with an air impact wrench still requires care to prevent overtightening. The air pressure to the air impact should be limited to 125 PSI (860 kPa) in most cases, and the proper adapter must be selected for the vehicle being serviced. The torque adapter absorbs any torque beyond its designed rating. Most adapters are color coded for easy identification as to the size of lug nut and torque value.

31. TIRE ROTATION
To ensure long life and even tire wear, tire rotation is essential.
It is important to rotate each tire to another location.
Some rear-wheel-drive vehicles, for example, may show premature tire wear on the front tires.

32. I Thought the Lug Nuts Were Tight!
Proper wheel nut torque is critical, as one technician discovered when a customer returned complaining of a lot of noise from the right rear wheel. SEE FIGURE 5–16 for a photo of what the technician discovered. The lug (wheel) nuts had loosened and ruined the wheel.

33. I Thought the Lug Nuts Were Tight!
FIGURE 5–16 This wheel was damaged because the lug nuts were not properly torqued.

34. TIRE ROTATION
FIGURE 5–17 The method most often recommended is the modified X method. Using this method, each tire eventually is used at each of the four wheel locations. An easy way to remember the sequence, whether front wheel drive or rear wheel drive, is to say to yourself, “Drive wheels straight, cross the nondrive wheels.”

35. TIRE INSPECTION
All tires should be carefully inspected for faults in the tire itself or for signs that something may be wrong with the steering or suspension systems of the vehicle.
FIGURE 5–18 Tire showing excessive shoulder wear resulting from underinflation and/or high-speed cornering.

36. TIRE INSPECTION
FIGURE 5–19 Tire showing excessive wear in the center, indicating overinflation or heavy acceleration on a drive wheel.
FIGURE 5–20 Wear on the outside shoulder only is an indication of an alignment problem.

37. All-Wheel-Drive Tire Concerns
It is very important that all-wheel-drive vehicles be equipped with tires that are all the same outside diameter. If, for example, the vehicle has 20,000 miles and the tires are half worn, all of the tires should be replaced in the event of a problem requiring replacement of only one tire.
Most vehicle manufacturers specify that all tires must be within 2/32 in. of tread depth without causing a constant strain on the drive train.

38. Both of these problems cause a tramp or up-and-down-type vibration.
RADIAL RUNOUT
Even though a tire has no visible faults, it can be the cause of vibration.
If vibration is felt above 45 mph, regardless of the engine load, the cause is usually an out-of-balance or a defective out-of-round tire.
Both of these problems cause a tramp or up-and-down-type vibration.
If the vibration is seen in the hood of the vehicle or felt in the steering wheel, then the problem is usually the front tires.
If the vibration is felt throughout the entire vehicle or in the seat of your pants, then the rear tires (or drive shaft, in rear-wheel-drive vehicles) are the problem.

39. RADIAL RUNOUT
FIGURE 5–22 To check wheel radial runout, the dial indicator plunger tip rides on a horizontal surface of the wheel, such as the bead seat.
FIGURE 5–21 A tire runout gauge being used to measure the radial runout of a tire.

40. RADIAL RUNOUT
To check radial runout (checking for out-of-round) and lateral runout (checking for side-to-side movement), follow these steps:
Raise the vehicle so that the tires are off the ground approximately 2 in. (5 cm)
Place the runout gauge against the tread of the tire in the center of the tread and, while rotating the tire, observe the gauge reading
Note that maximum radial runout should be less than in. (1.5 mm).
Check all four tires

41. I Thought Radial Tires Couldn’t Be Rotated!
When radial tires were first introduced by American tire manufacturers in the 1970s, rotating tires side-to-side was not recommended because of concerns about belt or tread separation. Since the late 1980s, most tire manufacturers throughout the world, including the United States, have used tire-building equipment specifically designed for radial-ply tires. These newer radial tires are constructed so that the tires can now be rotated from one side of the vehicle to the other without fear of causing a separation by the resulting reversal of the direction of rotation.

42. RADIAL RUNOUT CORRECTING RADIAL RUNOUT
Excessive radial runout may be corrected by one of several methods:
Try relocating the wheel on the mounting studs.
Remount the tire on the wheel 180 degrees from its original location.
If runout is still excessive, remove the tire from the wheel and check the runout of the wheel.

43. Is the Age of a Tire Important?
Yes. The National Highway Traffic Safety Administration (NHTSA) recommends that any tire six years old or older should be replaced regardless of tread depth. This means that tires that look almost like new but are six years old or older should be replaced because the NHTSA determined that age, not tread depth, was a major factor in tire failures.

44. LATERAL RUNOUT
Another possible problem that tires can cause is a type of vibration called shimmy.
This rapid back-and-forth motion can be transmitted through the steering linkage to the steering wheel.
Excessive runout is usually noticeable by the driver of the vehicle as a side-to-side vibration, especially at low speeds between 5 and 45 mph (8 and 72 km/h).
Shimmy can be caused by an internal defect of the tire or a bent wheel.
This can be checked using a runout gauge on the side of the tire or wheel to check for lateral runout.

45. LATERAL RUNOUT
FIGURE 5–23 To check lateral runout, the dial indicator plunger tip rides on a vertical surface of the wheel, such as the wheel flange.

46. LATERAL RUNOUT
FIGURE 5–24 The most accurate method of measuring wheel runout is to dismantle the tire and take dial indicator readings on the inside of the wheel rim.

47. The Greased Wheel Causes a Vibration
Shortly after an oil change and a chassis lubrication, a customer complained of a vibration at highway speed. The tires were checked for excessive radial runout to be certain the cause of the vibration was not due to a defective out-of-round tire. After removing the wheel assembly from the vehicle, excessive grease was found on the inside of the rim. Obviously, the technician who greased the lower ball joints had dropped grease on the rim. After cleaning the wheel, it was checked for proper balance on a dynamic computer balancer and found to be properly balanced. A test-drive confirmed that the problem was solved.

48. LATERAL RUNOUT CORRECTING LATERAL RUNOUT
Excessive lateral runout may be corrected by one of several methods:
Re-torque the wheel in the proper star pattern to the specified torque. Unequal or uneven wheel torque can cause excessive lateral runout.
Remove the wheel and inspect the wheel mounting flange for corrosion or any other reason that could prevent the wheel from seating flat against the brake rotor or drum surface.
Check the condition of the wheel or axle bearings. Looseness in the bearings can cause the wheel to wobble.

49. TIRE BALANCING
Proper tire balance is important for tire life, ride comfort, and safety.
Tire balancing is needed because of the lack of uniform weight and stiffness (due to splices) and a combination of wheel runout and tire runout.
Balancing a tire can compensate for most of these conditions.
However, if a tire or wheel is excessively out of round or bent, then replacement of the wheel or tire is required.

50. TIRE BALANCING
STATIC BALANCE
DYNAMIC BALANCE
PREBALANCE CHECKS
WHEEL WEIGHTS
BUBBLE BALANCER
COMPUTER BALANCER

51. TIRE BALANCING
FIGURE 5–25 A wheel balancer detects heavy spots on the wheel and tire, and indicate where to place weight to offset both static and dynamic imbalance.

52. TIRE BALANCING
FIGURE 5–26 An assortment of wheel weights designed to fit different shaped rims.

53. The Vibrating Ford Van
A technician was asked to solve a vibration problem on a rear-wheel-drive Ford van. During a test-drive, the vibration was felt everywhere—the dash, the steering wheel, the front seat, the shoulder belts; everything was vibrating! The technician balanced all four tires on a computer balancer. Even though wheel weights were put on all four wheels and tires, the vibration was even worse than before. The technician rebalanced all four wheels time after time, but the vibration was still present. The shop supervisor then took over the job of solving the mystery of the vibrating van. The supervisor balanced one wheel/tire assembly and then tested it again after installing the weights. The balance was way off! The supervisor broke the tire down and found about 1 quart (1 liter) of liquid in the tire! Liquid was found in all four tires. No wonder the tires couldn’t be balanced! Every time the tire stopped, the liquid would settle in another location.

54. The Vibrating Ford Van
The customer later admitted to using a tire stop-leak liquid in all four tires. Besides stop leak, another common source of liquid in tires is water that accumulates in the storage tank of air compressors, which often gets pumped into tires when air is being added. All air compressor storage tanks should be drained of water regularly to prevent this from happening.

55. The Vibrating Ford Van
FIGURE 5–27 Liquid tire stop leak was found in all four tires. This liquid caused the tires to be out of balance.

56. Stop Leak Can Damage TPMS Sensors
Stop leak should never be used in a tire that is equipped with the TPMS sensor because the sensor can be damaged.

57. TIRE BALANCING
FIGURE 5–28 Stick-on weights are used from the factory to balance the alloy wheels of this Prowler.

58. TIRE BALANCING
FIGURE 5–29 Wheel weight pliers are specially designed to remove and install wheel weights.

59. How Much Is Too Much Weight?
Whenever balancing a tire, it is wise to use as little amount of weight as possible. For most standard-size passenger vehicle tires, most experts recommend that no more than 5.5 oz of weight be added to correct an imbalance condition. If more than 5.5 oz is needed, remove the tire from the wheel (rim) and carefully inspect for damage to the tire or the wheel. If the tire still requires more than 5.5 oz and the wheel is not bent or damaged, replace the tire.

60. TIRE BALANCING
FIGURE 5–30 A tire balancer that can also detect radial and lateral force variation and instruct the operator where to rotate the tire to achieve the best ride, or indicate a bent wheel.

61. Are the Brake Drums and Rotors Balanced?
Whenever an off-the-vehicle computer balancer is used, a question often asked by beginning technicians is, “What about the balance of the brake drums and rotors?” Brake drums and rotors are balanced at the factory, usually to within 0.5 oz-in. Imbalance measured in oz-in. means that any imbalance force is measured in ounces, then multiplied by the distance from the center measured in inches. This means that at a distance of 1 in. from the center of the drum or rotor, it is within 0.5 ounce of being perfectly balanced. Being within 0.5 ounce inch also means that at 5 inches from the center, the imbalance is only 0.1 ounce.

62. Are the Brake Drums and Rotors Balanced?
What this means to the technician is that most drums and rotors are balanced well enough not to be a problem when using off-the-vehicle balancers. However, the smart technician should look for evidence that weights have been removed from brake drums to permit aluminum wheels to fit, or other cases where the factory balance of the drums and rotors has been changed.

63. REPLACEMENT WHEELS
Whenever a replacement wheel is required, the same offset should be maintained.
If wider or larger-diameter wheels are to be used, consult a knowledgeable wheel or tire salesperson to determine the correct wheel for your application.
FIGURE 5–31 Most brake drums do not have this much attached weight.

64. It Happened to Me—It Could Happen to You
During routine service, I rotated the tires on a Pontiac Trans Am. Everything went well and I even used a torque wrench to properly torque all of the lug nuts. Then, when I went to drive the car out of the service stall, I heard a horrible grinding sound. When I hoisted the car to investigate, I discovered that the front wheels were hitting the outer tie rod ends. The 16-in. wheels had a different back spacing front and rear, and therefore these wheels could not be rotated. Always check replacement or aftermarket wheels for proper fit before driving the vehicle.

65. It Happened to Me—It Could Happen to You
FIGURE 5–32 Notice that the rim touches the tie rod end.

66. What Are Hubcentric Wheels?
Most wheels are designed to fit over and be supported by the axle hub. Some wheels use an enlarged center hub section and rely on the wheel studs for support and to keep the wheel centered on the axle. Some aftermarket wheels may be designed to fit several different vehicles. As a result, the wheel manufacturers use plastic hubcentric adapter rings.

67. What Are Hubcentric Wheels?
FIGURE 5–33 (a) A hubcentric plastic ring partially removed from an aftermarket wheel. (b) A hubcentric plastic ring left on the hub when removing a wheel.

68. TIRE REPAIR
Tread punctures, nail holes, or cuts up to 1/4 in. (2.6 mm) can be repaired.
Repairs should be done from the inside of the tire using plugs or patches.
The tire should be removed from the rim to make the repair.
With the tire off the wheel, inspect the wheel and the tire for hidden damage.

69. The proper steps to follow for a tire repair are as follows:
Mark the location of the tire on the wheel.
Dismount the tire; inspect and clean the punctured area with a prebuff cleaner.
Buff the cleaned area with sandpaper or a tire-buffing tool until the rubber surface has a smooth, velvet finish.
Ream the puncture with a fine reamer from the inside. Cut and remove any loose wire material from the steel belts.

70. TIRE REPAIR
Fill the puncture with contour filling material, and cut or buff the material flush with the inner liner of the tire.
Apply chemical vulcanizing cement and allow to dry.
Apply the patch and use a stitching tool from the center toward the outside of the patch to work any air out from between the patch and the tire.
Remount the tire on the rim, aligning the marks made in step 1.

71. TIRE REPAIR
FIGURE 5–34 The area of the repair should be buffed slightly larger than the patch to be applied.

72. TIRE REPAIR
FIGURE 5–35 A stitching tool being used to force any trapped air out from under the patch.

73. TIRE REPAIR
FIGURE 5–36 A rubber plug being pulled through a hole in the tire. The stem is then cut off flush with the surface of the tire tread.

74. Dispose of Old Tires Properly
Old tires cannot be thrown out in the trash. They must be disposed of properly. Tires cannot be buried because they tend to come to the surface. They also trap and hold water, which can be a breeding ground for mosquitoes. Used tires should be sent to a local or regional recycling center where the tires will be ground up and used in asphalt paving or other industrial uses. Because there is often a charge to dispose of old tires, it is best to warn the customer of the disposal fee.

75. WARNING
Most experts agree that tire repairs should be done from the inside. Many technicians have been injured and a few killed when the tire they were repairing exploded as a steel reamer tool was inserted into the tire. The reamer can easily create a spark as it is pushed through the steel wires of a steel-belted tire. This spark can ignite a combustible mixture of gases inside the tire caused by using stop leak or inflator cans. Since there is no way a technician can know if a tire has been inflated with a product that uses a combustible gas, always treat a tire as if it could explode.

76. Open-End Wrenches Make It Easier
Tire repair is made easier if two open-end wrenches are used to hold the beads of the tire apart.

77. SUMMARY
For safety and proper vehicle handling, all four tires of the vehicle should be of the same size, construction, and type, except where specified by the manufacturer, such as on some high-performance sports cars.
Wheels should always be tightened with a torque wrench to the proper torque in a star pattern.
Tires should be rotated every 5,000 to 7,000 miles (8,000 to 11,000 km), or at every other oil change.
Wheels should be cleaned around the rim area whenever tires are changed and carefully inspected for cracks or other defects such as excessive lateral or radial runout.

78. SUMMARY
Properly balanced tires prolong tire life. Wheel tramp or an up-and-down type of vibration results if the tires are statically out of balance or if the tire is out-of-round.
Dynamic balance is necessary to prevent side-to-side vibration, commonly called shimmy.
Only coated or stick-on-type wheel weights should be used on alloy wheels to prevent corrosion damage.

79. REVIEW QUESTIONS
List the precautions and recommendations regarding tire selection and maintenance.
Determine the proper wheel mounting torque for your vehicle from the guidelines provided.
Describe how to check for lateral and radial runout of the wheels and tires.
Describe the difference between static and dynamic balance.

80. CHAPTER QUIZ
1. A tire is worn excessively on both edges. The most likely cause of this type of tire wear is ________.
Overinflation
Underinflation
Excessive radial runout
Excessive lateral runout

81. 2. When seating a bead of a tire, never exceed ________ PSI.
CHAPTER QUIZ
2. When seating a bead of a tire, never exceed ________ PSI. 30 40 50 60

82. CHAPTER QUIZ
3. For best tire life, most vehicle and tire manufacturers recommend tire rotation every ________.
3,000 miles
6,000 miles
9,000 miles
12,000 miles

83. 4. What lubricant should be used when mounting a tire?
CHAPTER QUIZ
4. What lubricant should be used when mounting a tire?
Silicone spray
Grease
Water-based soap
SAE 10W-30 engine oil

84. CHAPTER QUIZ
5. Using the modified X-method of tire rotation on a front-wheel-drive vehicle, where should be the left front wheel placed?
Right front
Right rear
Left rear
Kept at the left front

85. 6. Which statement is false?
CHAPTER QUIZ
6. Which statement is false?
Excessive radial runout can cause a tramp-type vibration.
Excessive lateral runout can cause a tramp-type vibration.
A tire out of balance dynamically can cause a shimmy-type vibration.
A tire out of balance statically can cause a tramp-type vibration.

86. CHAPTER QUIZ
7. The recommended type of wheel weight to use on aluminum (alloy) wheels is ________.
Lead with plated spring steel clips
Coated (painted) or stick-on lead weights
Lead weights with longer-than-normal clips
Aluminum weights

87. CHAPTER QUIZ
8. Most vehicle and tire manufacturers recommend that no more than ________ ounces of balance weight be added to a wheel/tire assembly.
2.5
3.5
4.5
5.5

88. CHAPTER QUIZ
9. A vehicle vibrates at highway speed. Technician A says that water in the tire(s) could be the cause. Technician B says that an out-of-round tire could be the cause. Which technician is correct?
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B

89. 10. Proper tire inflation pressure information is found ________.
CHAPTER QUIZ
10. Proper tire inflation pressure information is found ________.
On the driver’s door or post
In the owner’s manual
On the sidewall of the tire
Both a and b