Wheel alignment refers to the proper setting of the axle geometry as well as tracking of all axles on a vehicle. The purpose of the alignment is to:
- Minimize tyre wear
- Maximize predictable handling and driver control.
- Overall safer vehicle operation.
Have your alignment checked periodically as specified by vehicle manufacturer manual or whenever there is a indication of trouble such as uneven wear in tyres, pulling, vibrations etc.
Major Vehicle Alignment Factors That Affect Tire Life:
It is also recommended that tyre wheel assembly should be checked for proper balancing.
- Toe Settings: First and foremost
- Rear Axle Alignment Geometry: 2nd
- Camber: 3rd
- The purpose of toe is to allow the tire to run straight during normal operating conditions
- Deviation from this condition results in either:
- toe-in or positive toe
- toe-out or negative toe
Toe In / Positive Toe
Positive toe is necessary for improved tread life
Toe-Out / Negative Toe
Negative Toe accelerates tread wear
Rear Axle Alignment
- Affects vehicle tracking
- Terms utilized in rear axle alignments:
- Parallelism = Scrub = skew = tram
- Thrust angle = square
Parallelism, Scrub, Skew or Tram
- Parallelism, scrub, skews or tram is referenced by the angle formed by two lines projected through the length of the axle. This angle is sometimes simplified into a measurement between the difference in axle spacing on opposite sides of the vehicle.
- Angle measured between two rear axles
Effects of Parallelism, Scrub, Skew or Tram:
- Causes ALL axles to work against each other
- Requires steer axle to be turned to compensate for the “push” of the rear axles to keep the vehicle moving in a straight path
- Camber is the inward or outward tilt of the top of the tires when viewed from the front of the vehicle
- Labeled as either positive or negative
Wear Characteristics Due To Excessive Camber:
- Excessive positive camber:
- smooth wear patterns on the outer half of the tire tread
- Excessive negative camber:
- smooth wear patterns on the inner half of the tire tread
- The state of all wheels should be regularly checked. Any cracked wheel or rim should be replaced.
- Wheels or rims should not be repaired by welding. If a welding operation has to be undertaken, the tyre must be removed from the rim. If this is not done, there is a serious risk of explosion.
- The tyre should only be refitted when all items have returned to ambient temperature.
- Before any welding on the vehicle chassis or at proximity of the tyres, the tyre and wheel assemblies should be removed from the vehicle.
- Before removing divided wheel assemblies from a vehicle, it is recommended that the tyres are deflated