Caster

Picture the line the front wheel pivots around when you steer. Seen from the side, it usually tilts back at the top, like the forks on a bicycle. That backward tilt is positive caster. It makes the wheels want to straighten themselves, which is why the steering wheel returns to center when you let it slide through your hands.

Caster also has a useful side effect in corners: as you add steering, it tilts the outside front wheel toward negative camber, exactly when that tire is loaded. More caster therefore often means better front grip mid-corner, plus heavier steering and more feedback through the rim.

Most drivers never adjust caster directly, but you feel it. A car that tramlines, wanders, or has vague, light steering may be short on caster. Too much makes the steering heavy at low speed. It is set during an alignment along with camber and toe.