TIGHT: Also known as understeer.This occurs when the front wheels lose traction before the rear wheels. It causes the stock car to have trouble steering sharply and smoothly through the turns as the front end pushes towards the wall.
LOOSE: Also known as oversteer. This occurs when the rear tires of the stock car have trouble sticking in the corners. This causes the car to fishtail as the rear end swings outward while running through the corners.
During a pitstop, one of the crewman will sometimes add or subtract spring pressure by attaching a ratchet, and manually rotating it one way or another. This tightens or loosens the spring, and brings the frame or trailing arm forward or away from each other, applying more or less pressure on the tire when the car goes into a turn. This is known as adding or subtracting wedge.