Wheel Alignment

Wheel Alignment is an important feature of any car’s setup and is often over-looked by many drivers. For a car to drive and perform to its optimum, it is important that wheel alignment is carried out at regular intervals. STS provide a full Wheel Alignment service, for more information call 01234 269800.

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STS use the latest machines and technology to provide a tracking and Four-Wheel Alignment service. Four Wheel Alignment will give a minimum of 12 angles measured, all referenced to the car wheel centreline and display these alignment angles and compare them to the factory alignment data. This will ensure your car is set-up perfectly.

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Why & when would I need to align my car?

Poor wheel alignment can occur for many reasons. Sometimes it can need adjusting over time as your vehicle takes on the stresses of daily driving or become mis-aligned during accidents/collisions. The symptoms of poor alignment are often very easy to recognise. The most frequent include:

– When the steering wheel does not sit straight
– The vehicle pulls to one side when in motion
– Tyres are wearing out quickly and/or unevenly
– Vibration in the steering wheel
– The steering wheel feels unusually loose

An example of mis-alignment…

By viewing the diagram below, you can see that the front wheels of the vehicle are not aligned to the rear thrust line. This can be caused through normal wear, stress and everyday driving.


In this example, if the driver was to steer straight ahead, they would feel the car ‘pulling to the side’. This would result in the driver continuously having to adjust the steering wheel in order to keep the car in a straight line. It only takes a very small mis-alignment for this to happen and often results in an uncomfortable drive and uneven tyre wear.

Want to learn more?

STS realise the importance of explaining their work to the customers but are aware not everyone needs to know or indeed want an in-depth knowledge! So for those of you who want to learn more about camber…castor…toe in/out and the dynamics actually involved in wheel alignment – read on!

1) Camber

Camber increases or decreases the tyre’s grip on the road by the wheel not being upright, when viewed from the front or rear. Correct camber is a design requirement and incorrectly set at best will cause tyre wear but at worse could seriously compromise the overall handling characteristics of the car – even making it dangerous.

2) Caster

Caster is the forward or rearward tilt of the steering axis, in reference to the vertical when viewed from the vehicle side.  Positive caster is where the steering axis is sloped towards the rear. Negative caster (not common) is where the steering axis is sloped towards the front.

3) Toe

Positive Toe is the leading edge of the wheels closer together. Negative Toe is the leading edge of the wheels further apart. Our advice would be not to refer to toe as toe-in. For example negative toe-in is toe out! Better to simply say the car has negative toe or is toed out.


Cars generally no longer have kingpins and hence the term KPI is outdated. SAI stands for Steering Axis Inclination and it will be referred to subsequently by this. When viewed from the front the SAI is the inclination of the strut top towards the centre of the vehicle, and in all cases is positive.

5) Thrust Angle

Thrust angle (other than zero) occurs when the individual rear toe values are unequal. The easiest example to imagine is for a car with a live rear axle (one piece) that has the axle fitted crocked in the body such that one rear wheel has toe-in and the other one has toe-out. Thrust line is an angle of the resultant drive direction compared to the vehicle centreline. Cars driven with high thrust angles may appear to ‘crab’.


Setback is the relative positions of the two wheels on an axle. Setback can be given in mm or as an angle i.e. degrees and minutes.