Akerman
A steering geometry design that lets inner wheels turn more sharply than outer wheels during a corner.

Alignment
The adjustment of a vehicle’s suspension angles ensures the wheels are positioned correctly relative to each other and the road.

Balance
The vehicle’s handling equilibrium between understeer and oversteer.

Bump Steer
Unwanted toe change caused by suspension movement over bumps.

Camber
The inward or outward tilt of a wheel when viewed from the front.

Camber Gain
The change in camber angle as the suspension moves through its travel.

Castor
The forward or rearward tilt of the steering axis when viewed from the side.

Combined Angle
The sum of camber and slip angles that determines a tyre’s actual direction of travel.

Contact Patch
The area of a tyre that is in direct contact with the road surface at any given moment, transmitting all acceleration, braking, and cornering forces.

Geometry
The collection of suspension angles that determines how wheels move and steer.

Instant Centre
The point in space where the upper and lower suspension arms—when their pivot axes are extended—intersect to define the wheel’s momentary pivot point.

King Pin Inclination (KPI)
Another term for SAI, describing the inward tilt of the steering pivot.

Oversteer
A handling condition where the rear tyres lose grip first, making the vehicle turn more sharply than intended.

Roll Centre
The theoretical point around which the vehicle’s body rolls, determined by suspension geometry and the location of each side’s instant centre.

SAI (Steering Axis Inclination)
The inward tilt of the steering axis when viewed from the front.

Scrub Radius
The distance between the steering axis line and the tyre’s contact patch on the road.

Swing Axle Inclination
The tilt of a swing-axle’s pivot line affects camber change during suspension movement.

Thrust Angle
The angle between a vehicle’s geometric centerline and the direction in which the rear wheels actually push the car, indicating whether the vehicle tracks straight or “crabs” to one side.

Toe
The angle at which the wheels point inward or outward when viewed from above.

Toe In
A toe condition where the front of the wheels point toward each other.

Toe Out
A toe condition where the front of the wheels points away from each other.

Tyre Sizing
The standardised code that specifies a tyre’s width, aspect ratio, construction type, and wheel diameter, along with load and speed ratings.

Understeer
A handling condition where the front tyres lose grip first, making the vehicle turn less than intended.