Wheel alignment: what is it and why should you care?

wheel alignment explained

Noticed your tyres are wearing unevenly, or you’ve felt a shudder through the steering wheel? Here’s everything you need to know about wheel alignment and why it matters.

Our wheels and tyres rarely get the attention they deserve until something goes properly wrong, or our mechanic says the tyres need replacing. We’ve already looked at tyre rotation and this is a job that anyone can do at home with a few basic (but vital) bits of kit. When it comes to wheel alignment, well, it is possible to do a basic alignment at home but it’s best left to the professional at a shop.

What is a wheel alignment?

Your car’s wheels are typically not designed to run perfectly vertically upright, or point straight ahead. The degree to which they are not vertical is known as camber (negative and positive), and whether they point straight ahead or not is known as toe (in or out).

A wheel alignment is the measurement of both your vehicle’s suspension and wheels and adjusting accordingly to ensure they’re in the correct camber, toe and other specifications such as caster.

If your car is out of alignment, then handling will be compromised, fuel consumption will probably increase, and tyres will wear faster or abnormally.

An alignment tech at work. The device on the rear wheel measures camber and toe.

How can you tell if you need a wheel alignment?

There are tell-tale signs that your wheel alignment is out, and the most obvious are that your vehicle may be pushing to the left or right and you’re constantly having to adjust the steering to keep it travelling straight. You might feel constant vibration through the steering wheel, your steering wheel is cocked off centre. But the most obvious ‘tell’ requires you to look at your tyres and check the tread wear to see whether the wear is uniform or not. If not, then you’ve got a wheel alignment issue. If you notice any of these things you should take your vehicle to your mechanic or a tyre fitment centre and describe the issue with them.

It’s all in the tread wear

The way your tyre’s tread wears can tell you a lot about what’s going on with your vehicle. For instance, if you notice the tread has become smooth on one side of the tyre and is sharp on the other side, then you’ll likely be looking at a new set of tyres and wheel alignment. Then there’s camber wear which is when both outside edges of the tyre are wearing but the centre of the tyre isn’t. Too much positive or negative camber is usually the cause. Heel/Toe Wear relates to when one side of the tread block is wearing faster than its opposite side. Look at the tyre from the side and it’ll look like the teeth on a saw blade. This is less of an alignment issue and more of an under inflation and/or poor rotation pattern issue. Regardless, it’s an indication that something’s wrong.

mechanic fixing wheel alignment

What’s the wheel alignment technician looking for?

Camber, toe and caster. There will be factory specifications for the allowable tolerances, and the technician will look to bring the vehicle within those specifications. Sometimes, knowledgeable owners go outside the specifications, fore example some sports car owners sacrifice a little straight-line stability for better agility. Here’s the main three alignment specifications:

Camber is the angle of your wheel and tyre package when looked at head on. Meaning, if the top of the wheel/tyre is angled in towards the vehicle then this is called Negative Camber. Positive Camber is when the top of the wheel/tyre is angled away from the vehicle. Both can be caused by things like worn bearing, bushes and ball joints. Camber is adjustable on most cars, except live-axled vehicles.

Toe is whether your wheels/tyres point inwards or outwards when looked at from above, too much one way or the other will cause your tyres to wear prematurely, cause pressure on wheel and suspension components and make the handling poorer. Toe is adjustable on most cars, except the rear of live-axled vehicles.

Caster is a critical one as its directly linked to steering control, stability and cornering. The simplest way to describe this one is that it relates to the angle of the steering and suspension components. If they’re angled back towards the vehicle then it’s called Positive Caster and if it’s angled towards the front, then it’s called Negative Caster. The latter isn’t usually an issue as most modern cars run Positive Caster – this is what makes our front wheels want to self-centre and ensures straight line stability at speed. Negative caster, however, is a problem, this causes the steering and front wheels to feel loose and leaves you with a feeling your vehicle is wandering on the road. Caster is not usually adjustable on roadcars, so if it’s out, there’s a problem!

tyre wear pattern

What is wheel balancing?

A tyre and wheel are never perfectly symmetrical. There will always be a little bit of weight one side or the other. At speeds above 40km/h or so the car occupants feel this imbalance as a vibration which worsens with increasing speed.

The solution is wheel balancing. The simplest method is spin balancing, where each wheel and tyre is placed onto a machine that will spin the tyre and look for any areas of imbalance; these are dealt with via the placement of small weights on the wheel.

Road-force balancing achieves the same effect, but rather than just spin the tyres, presses a roller against it while it spins to simulate road force, giving a more accurate balance.

How often should you check the alignment?

A good rule of thumb is to have the wheel/tyre alignment checked at each vehicle service, and definitely whenever you have a new set of tyres fitted. Keeping a regular eye on your tyres and how they’re wearing, and the pressure your running is vital to keep them in top condition. Make sure you get a printed report from the alignment technician, and ensure they explain what, if any the problems are. The report will show whether your car was within factory spec limits or not, and whether the technician was able too adjust the alignment to within specifications.

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