Wheel geometry: Toe-in

Toe-in is the difference between A and B. If the wheels are exactly parallel, with the two dimensions A and B equal, toe-in will be zero.

Toe-in must always be positive, that is to say dimension B must be greater than dimension A. B less A = positive toe-in.

Front wheel toe-in is adjusted by lengthening or shortening the track rods. Correct toe-in improves directional stability. Toe-in must be adjusted by an equal amount on both left-hand and right-hand track rods to ensure that the steering wheel spokes will be positioned symmetrically.

Rear wheel toe-in is adjusted by moving the longitudinal links attached to the body outwards (to reduce toe-in) or inwards (to increase toe-in). Rear wheel toe-in is always measured relative to the car's axis of symmetry. The axis of symmetry is an imaginary line drawn between the center points of the front and rear axles.

In connection with wheel alignment, equipment for 4-wheel measurement must be used because the rear wheels must be aligned before the front wheels and serve as reference points for the front wheels. The car's behavior on the road is dependent on correct alignment of the wheels.

Incorrect toe-in gives rise to vibration which leads to increased tire wear as the tires then scrub sideways. Excessive toe-in often causes wear on the outer shoulders of the tires.