Wheel alignment, also known as tyre alignment can help your tyres function properly, achieve even wear on all four tyres, plusing making them last longer. It’s an elaborate process and each car manufacturer has their own designated alignment angles.
Maintaining the correct wheel alignment is crucial to avoid your vehicle from pulling in one direction or vibrating strangely on the road.
The basics of wheel alignment is made up of three basic adjustments – camber, caster, and toe. Each has a specific purpose and function, and we will explain it to you in the simplest way possible.
Keep in mind that racing cars have a different, almost opposite approach to wheel alignment. The below is applicable only for road cars.
What is wheel alignment and how do I know I need to get it fixed?
Wheel alignment refers to the adjustment of suspension component rather than the tyre or the wheel itself. There are several ways to tell:
- Uneven tyre wear
- Vehicle is pulling to the left or right when you're going straight
- The steering wheel is not centered while driving straight
- Vibration at the steering wheel
What is camber, caster, and toe?
Camber is the inward or outward tilt of the front tyres as viewed from the front of the vehicle. Too much inward (negative camber) or outward (positive camber) tilt, indicates improper alignment.
Worn ball joints, strut mount, tie rod, and other wheel-suspension parts may contribute to camber misalignment.
Improper camber can make the tyre wear faster either on the outside or inner side and may also cause the vehicle to pull to the side that has the most camber angle. Ideally, you want zero camber all around as this will result in the most uniform tyre wear over time, but doing so may reduce performance during cornering.
Not all cars runs zero camber, as the optimal camber setting depends on car type, purpose, driving style, and the conditions the vehicle is being driven in.
A spirited driver or track racer would prefer negative camber as it will maximize the tyre contact patch for better stability during hard cornering.
Forget positive camber, it will only reduce handling and stability for road cars, hence why you don’t see any of this on a modern road car.
Caster refers to the angle that is created by the steering pivot point in relation to the front and the back of the car. In simpler words - picture the side of a vehicle, now imagine a vertical axis (line) that runs straight through the center of your front wheels.
Caster is positive if the line is angled forward, and negative if backward. Generally, road car runs cross-caster, neutral caster or positive caster, rarely a negative caster.
Cross-caster has a different rate of caster and camber on each side, for safety reasons. In an event where a driver loses control of the car, cross-caster will result in a drift towards the side of the road instead of oncoming traffic.
Caster angle affects three things – steering effort, stability and cornering. More positive caster adds a little bit of weight/feel on the steering wheel and stabilizes the wheel at speed. It helps to keep the vehicle traveling in a straight line and return the tyre to an upright position when coming out of a turn.
While cornering, caster increases tyre lean, which helps the car to corner better and assist in the the steering wheel self-centering after a turn.
Toe represents the angle derived from pointing the tyres inward or outward, when viewed from top-down view on the front wheel – much like looking down at your feet and angling them inward (toe-in) or outward (toe-out). Both require adjustment.
Correct toe is important to even out the tyre's tread wear and extend service life. Toe-in allows both wheels to constantly generate force against one another, which reduces turning ability. However, positive toe creates better straight line driving characteristics and reduces oversteer.
Toe-out increases a car cornering ability, while reducing understeer. When the car begins to turn towards a corner, the inner wheel will be angled more aggressively. Since its turning radius is smaller than the outer wheel, it will pull the car in that direction easily. However, it will also decrease straight-line stability.
Wheel alignment is crucial to get the correct driving feel. Following the settings designed by the car manufacturer is important as it affects the car's driveability, handling, and making the best out of your tyres. Any deviation from the designated angles may result in dangerous and unstable behavior, especially on a road car.
For the spirited driver or track racer, your alignment will of course be different from the manufacturer's specs but you need to know what you're doing. Hence, please make sure to get professional advice and do a thorough research if you intend to do any suspension modifications as this will affect your camber, caster, and toe.