Bathwick Tyres

Wheel Alignment

How do I know when my car needs to be realigned?

If you're wondering whether your car needs an alignment, first look at your tyres.

Uneven tyre wear -- often, more wear on the edges of some tyres -- is a prime indicator that your car is likely out of alignment.

Here are a few more indicators:

  • your car seems to be drifting to one side, even when you think you're driving straight

  • your steering wheel vibrates

  • you are driving straight, but your steering wheel isn't centered

  • your car has understeer or oversteer

  • your experiencing uneven tyre wear

Improved Fuel Ecvonomy

IMPROVED FUEL ECONOMY - poor alignment increases the rolling resistance of tyres. About 30% of a vehicle's fuel is used to overcome the tyres rolling resistance, and just a small amount of misalignment can increase fuel consumption dramatically. Savings of up to 5% on fuel can readily be achieved through accurate alignment

A car alignment is actually an elaborate process that brings the car's suspension into its proper configuration, positioning and adjusting components so that wheels are aligned with one another and the road surface. The alignment should be performed by an experienced mechanic, who uses an alignment machine.

Newer alignment machines feature clamplike devices that are attached to the wheels of the car (which is raised up in the air) and that link to a computer that helps make precise measurements. The mechanic will also take this opportunity to make sure that no suspension components are excessively worn or broken.

Toe

The vehicle's toe is the most critical alignment settings relative to tyre wear. if the toe setting is just 1/32-inch off of its appropriate setting, this will reduce tyre life.

Like camber, toe will change depending on vehicle speed, as aerodynamic forces changes the riding height hence affecting camber and toe due to the geometry of the steering linkage in relation to the geometry of the suspension.

The toe angle identifies the direction of the tyres compared to the centerline of the vehicle. Rear-wheel drive vehicle "pushes" the front tyres, as they roll along the road, resistance causes some drag resulting in rearward movement of the suspension arms against their bushings. Most rear-wheel drive vehicles use positive toe to compensate for suspension movement.

Front-wheel drive vehicle "pulls" the vehicle, resulting in forward movement of the suspension arms against their bushings. Most front-wheel drive vehicles use negative toe to compensate for suspension movement.

Be aware that toe setting influences tyre wear. Excessive toe settings often causes drivability problems, especially during heavy rain. This is because most highways have tyre groves from the daily use by Lorries and trailers. These heavy vehicles leave groves that fill with water. When one of the vehicles front tyre encounters a puddle, it loses some of its grip, the other tyre's toe setting will push causing excessive toe-in, or pull causing excessive toe-out. This may cause the vehicle to feel unstable.

Perhaps the easiest concept to visualize is toe. Toe represents the angle derived from pointing the tyres inward or outward from a top-down view - much like looking down at your toes and angling them inward or outward.

Correct toe is paramount to even tread wear and extended tyre life. If the tyres are pointed inward or outward, they will scrub against the surface of the road and cause wear along the edges. Sometimes however, tread life can be sacrificed for performance or stability

Positive toe occurs when the front of both tyres begins to face each other. Positive toe permits both wheels to constantly generate force against one another, which reduces turning ability. However, positive tow creates straighter driving characteristics.

Typically, rear wheel drive vehicles have slightly positive tow in the rear due to rolling resistance - causing outward drag in the suspension arms. The slight positive toe straightens out the wheels at speed, effectively evening them out and preventing excessive tyre wear.

Negative toe is often used in front wheel drive vehicles for the opposite reason. Their suspension arms pull slightly inward, so a slight negative toe will compensate for the drag and level out the wheels at speed.

Negative toe increases a cars cornering ability. When the vehicle begins to turn inward towards a corner, the inner wheel will be angled more aggressively. Since its turning radius is smaller than the outer wheel due to the angle, it will pull the car in that direction.

Negative toe decreases straight line stability as a result. Any slight change in direction will cause the car to hint towards one direction or the other.

Conclusion

Vehicles are designed with manufacturer's settings for a reason. Countless hours of research and development go into designing suspension components and typically those numbers are the best to go with. Attempting to differ from the norm may result in dangerous conditions, especially for public road vehicles.

Steering Center

Steering centre is that the steering wheel is centered when the vehicle is traveling down a straight and level road. However, most roads are crowned to allow for water drainage, this may cause the vehicle to drift to the right so the steering wheel will appear to be off-centre to the left on a straight road.

A crooked steering wheel is one of the most common complaints after a wheel alignment. Steering centre is controlled by the front and rear toe settings, when setting steering centre, the rear toe should be set first bringing the Thrust Angle as close to the vehicle centreline as possible. the steering wheel is then locked in a straight-ahead position in order to set the front toe.

What causes incorrect alignment?

Wheel alignment can be affected by hitting the kurb or a large pothole in the road or travelling regularly on gravel roads. If alignment is out, it can cause excessive wear and problems with steering or suspension.

Wheel Alignment at Bathwick Tyres can be measured in 3 ways:

1) Toe - looks at how parallel the wheels are in relation to one another when viewed from above, toe in/out causes excessive tyre wear.
2) Camber - is the angle of the wheel in comparison to the road, when viewed from the front. Correcting the camber ensures your tyres are vertical to the road, to optimise the handling of your car.
3) Caster - looks at the angle of steering pivot when viewed from the side of the vehicle. Although adjustment on some cars is limited and caster settings don´t cause excessive wear on your tyres, it´s important to ensure the caster is equal on both sides of the car to avoid any problems with straight line stability and reduce the pressure on steering.

Checking and adjusting vehicle steering alignment is a skilled process and should only be carried out by a qualified technician. At Bathwick Tyres we have the latest equipment and skilled technicians to help set up your vehicle correctly. Please call us for any help and advice.