Camber, Caster, Toe & Thrust Angle Explained

SPEC RANGE

0.05° to 0.20° toe-in (most cars)

How parallel the wheels are to each other when viewed from above

Toe is the most-adjusted alignment angle and the most sensitive to road impacts. Toe-in means the front of each tire points slightly toward the centreline of the car. Toe-out is the opposite. Most modern cars run a slight toe-in to compensate for the natural tendency of front tires to splay outward under driving load. Toe error of just 0.5 degrees can cut tire life in half. The fix is straightforward: the tech adjusts the threaded tie rod ends until both wheels are parallel.

SPEC RANGE

-1.5° to +0.5° (depending on vehicle)

The vertical tilt of the wheel when viewed from the front

Zero camber is a perfectly vertical tire. Negative camber means the top of the wheel leans toward the car. Positive camber leans away. Most passenger cars run mild negative camber from the factory (0.5 to 1.5 degrees) to improve cornering grip as body roll effectively reduces camber on the loaded outside wheel. Adjustability varies by suspension design. Strut-based front suspensions, common on front-wheel-drive cars, often have no factory camber adjustment. Aftermarket camber bolts can add adjustment range when correction is needed.

SPEC RANGE

+3.0° to +8.0° positive caster

The forward-or-backward rake of the steering axis viewed from the side

Caster is the angle of the line between the upper and lower steering pivots when viewed from the side. Positive caster means the upper pivot sits behind the lower pivot (the strut leans backward at the top). Virtually every modern passenger car uses positive caster ranging from 3 to 8 degrees. Positive caster creates a self-centring steering feel and improves straight-line stability. Caster is rarely adjustable on standard strut suspensions, so a caster correction usually means a bent or worn part needs replacing.

SPEC RANGE

0° (rear axle parallel to centreline)

The angle between the rear axle's direction of travel and the car's geometric centreline

Thrust angle is what makes a car "dog track" if it is wrong: the rear of the car drives slightly off to one side of the front. On 4-wheel alignments, the rear is set first and the front is then adjusted relative to the rear thrust line, ensuring the steering wheel sits centred when the car tracks straight. On a solid rear axle, thrust angle cannot be adjusted; the front must be set to match whatever angle the rear has settled at.