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27 Cards in this Set
- Front
- Back
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Tires support the vehicle weight and absorb shock between the road and the suspensions. They also provide traction for acceleration and braking and steering control.
What are the construction of tires? |
- Bias Ply
- Bias Belted - Radial Belted (most commonly used) |
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Hydroplaning is the tendency of a tire to trap water between the tread and the pavement at high speeds.
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Slip angle is the difference between the angle of the tire and its actual direction of travel.
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Think of driving on icy road.
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Rim offset is the difference between the wheel mounting flange and the centerline of the wheel and tire assembly.
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Wheel balance is the equal distribution of weight around the circumference and width of the wheel and tire assembly.
What does unbalanced condition of wheels create? |
- Vibration and passenger discomfort
- Stress and wear on steering and suspension components - tire wear |
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Static balance is the equal distribution of weight around the center of the wheel.
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If a heavy spot exist on one area of the wheel and tire assembly, the wheel is said to be statically imbalanced.
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A wheel can be perfectly balanced statically and still be dynamically imbalanced.
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Dynamic balance is the equal distribution of weight on each side of the tire center line.
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If the weight of the wheel and tire assembly is uneven toward the edges of the wheel, the wheel is dynamically out of balance.
What condition does this create? |
- vibration
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What are wheel balancing methods?
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- On-car balancers
- Electronic Balancers |
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Torquing of wheel is critical to prevent damage to the wheel, the mounting flange or brake rotor.
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Most automotive wheel bearings are either tapered roller bearings or sealed ball bearings.
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What is tire deflection?
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The mass of the vehicle makes the actual rolling diameter of the tire smaller than the free diameter.
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What are the rim offsets?
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- Pos (+) offset places the tire centre inboard of the mounting flange.
- Neg (-) offset places the tire centre outboard of the mounting flange. - Zero offset places the mounting flange exactly at the physical centreline of the wheel. |
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How are split rims serviced?
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Split rims can be extremely dangerous and should not be serviced without special equipment and training.
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What adverse affect can a negative rim offset cause?
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- increase vehicle track width which will reduce the clearance between the tire and fender
- moves the wheel bearing load outward and increases the leverage the wheel can apply to the suspension and steering components. |
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What are the styles of wheel weights?
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- clip-on weights (coated or uncoated)
- adhesive weights |
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What are the common causes of bearing failure?
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- Brinelling (impact or shock load)
- Abrasive wear (foreign material) - Spalling (fatique wear) - Discoloration (lack of lubrication/overheating) |
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Check axle retaining nut torque first.
Sealed bearings should be inspected for looseness. What are manufacturer spec? |
- Commonly 0.005" (0.13mm)
- Others, if end play detected |
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The bearings must be adjusted before placing the vehicle in service.
What is the manufacturer spec? |
- Typically 0.001" to 0.005" (0.025mm to 0.125mm)
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over-inflation = wear on centre of tread
under-inflation = wear on shoulders What other causes of under-inflation? |
overheating and sidewall deterioration due to the excessive flexing of the side walls
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random worn spots = static imbalance
regular scalloping pattern? |
may have worn steering or suspension components or both
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What causes irregular diagonal wear pattern?
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Severe tracking or rear toe problems.
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What causes vehicle vibration?
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- static imbalance (especially over 56km)
- excessive radial runout of wheels - damaged tires such as missing or separated treads components |
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Any force that causes the front wheels to wobble side-to-side will produce steering wheel shimmy.
cause? |
- lateral wheel runout
- dynamic imbalance - bent wheels - shifted tire belts - tire pressures excessively low |
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Hub should be replaced if runout exceeds 0.13mm (0.005").
What is the maximum wheel and tire assembly runout? |
- 1.5 mm (0.060") for radial and lateral
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