Neutral camber
For most road cars, this is the preferred set-up. In effect, the wheel remains perpendicular to the road, with only a small amount of camber change caused by cornering load during cornering. Assuming all is well in the car’s alignment, then you should see even wear across the tyre’s tread.
Positive camber
As its name suggests, positive camber is the opposite of negative camber. In this set-up scenario, the top of the angle outwards and the bottom inwards. It’s the sort of arrangement you’ll spot on older, usually vintage machines. This is because it helps make the handling a little more predictable, even if it actively reduces grip and cornering forces grow.
Simplified, positive camber on the front wheels will promote severe early onset understeer, while used at the rear if promotes oversteer. While this is usually engineered into the design, sometimes it can be an undesirable side effect. Most famously, cars with swing axle rear suspension (early rear-engined Skodas or the Mercedes 300SL Gullwing) suffer from sudden positive camber at the rear, the wheels effectively tucking under themselves under big cornering loads which results in hairy, snap oversteer.
Again, large doses of positive camber are rare on modern road cars, but if you spot excessive wear to the outside edge of a wheel, then this could be the culprit (and once again worn suspension could be the issue.
Caster
In fairness, changes in caster angle are unlikely to result in extra or unusual tyre wear, as it doesn’t directly affect the way the tread and road surface interact. Look at the car side on and imagine a line going straight through the front wheel, from top to bottom – this is essentially the caster angle.
As with camber, there are negative, positive and neutral (zero) states of angle for the caster, with each having an effect on the steering.
Negative caster
This set-up is similar to that used on a shopping trolley, making the steering very easy to turn. However, the downside is that its effects are amplified during braking, making the steering more sensitive and the car feel less stable (imagine that trolley with one of its trademark wobbly wheels flailing around as you push it).
