WASHINGTON, D.C. — A light on motorists' instrument panels will soon warn them when a tire is underinflated. The safety regulation was issued by the government on April 7, according to a report by the Associated Press. The regulation has its roots in the Firestone tire recall of 2000, according to the report. It requires new passenger cars to have tire pressure monitoring systems in place by the 2008-model year. Automakers most likely will attach tiny sensors to each wheel that will signal if a tire falls 25 percent below the recommended inflation pressure. If any one of the four tires is underinflated, the sensor sets off a warning light. The National Highway Traffic Safety Administration (NHTSA) estimates the upgrade will cost manufacturers between $48.44 and $69.89 per vehicle, according to the Associated Press. The government said underinflated tires affect a vehicle's fuel economy and can increase stopping distances, contribute to the likelihood of tire failure and lead to skidding on wet surfaces. One NHTSA survey found about 30 percent of cars and light trucks have at least one tire underinflated by 8 lbs. per square inch or more. All new four-wheel vehicles weighing 10,000 lbs. or less must be equipped with the systems by the 2008-model year, the government said. The regulation affects passenger cars, sport utility vehicles, pickup trucks and minivans. NHTSA estimates that 120 lives a year will be saved when all new vehicles are equipped with the systems.