Perhaps the easiest concept to visualize is toe. Toe represents the angle derived from pointing the tires inward or outward from a top-down view – much like looking down at your toes and angling them inward or outward.
Correct toe is paramount to even tread wear and extended tire life. If the tires are pointed inward or outward, they will scrub against the surface of the road and cause wear along the edges. Sometimes however, tread life can be sacrificed for performance or stability
Positive toe occurs when the front of both tires begins to face each other. Positive toe permits both wheels to constantly generate force against one another, which reduces turning ability. However, positive tow creates straighter driving characteristics.
Typically, rear wheel drive vehicles have slightly positive tow in the rear due to rolling resistance – causing outward drag in the suspension arms. The slight positive toe straightens out the wheels at speed, effectively evening them out and preventing excessive tire wear.
Negative toe is often used in front wheel drive vehicles for the opposite reason. Their suspension arms pull slightly inward, so a slight negative toe will compensate for the drag and level out the wheels at speed.
Negative toe increases a cars cornering ability. When the vehicle begins to turn inward towards a corner, the inner wheel will be angled more aggressively. Since its turning radius is smaller than the outer wheel due to the angle, it will pull the car in that direction.
Negative toe decreases straight line stability as a result. Any slight change in direction will cause the car to hint towards one direction or the other.