Ever since radial tires with stiffer sidewalls have been used, changing the air pressure within the tires is used as another setup tool when adjusting spring rates in the vehicle’s suspension. If the air pressure is increased, the "spring rate" in the tire will raise. This changes the car’s handling characteristics. For example, if the racecar is "tight" coming off a corner, the driver might request a slight air pressure increase in the right rear tire to "loosen it up."
The final seven spots in a NASCAR race are reserved for drivers who qualify unsuccessfully during the weekend. These spots are determined by the points accumulated during past races.