ST. PETERS — Race cars and airplanes have used it for years in their tires, and now St. Peters residents can, too.
On Monday, St. Peters became the first city in the St. Louis area to offer its residents free nitrogen to fill their tires.
Proponents say putting nitrogen in tires reduces leaks, keeping tires properly inflated and providing better gas mileage. Critics say motorists can do just as well by frequently checking their tire pressure.
Regular air is about 78 percent nitrogen and 21 percent oxygen. The mixture available in St. Peters is almost 100 percent nitrogen.
A test by the National Highway Traffic Safety Administration showed that using nitrogen reduced tire pressure loss in new tires. The practice's benefits can diminish over time, though.
The new nitrogen tire-filling machine is part of a federal stimulus grant the city is using for various environmental projects.
Ron Darling, city director of health and environmental services, estimated that using nitrogen could save a motorist 15 gallons of gasoline in a year's time.
Gordon Anzalone, 70, one of the residents who scheduled an appointment to have his tire air replaced on Monday, wasn't sure it would help but was willing to give it a try.
"I guess the proof is in the pudding," he said.
Anzalone's Jeep Grand Cherokee sank as hoses simultaneously let the air out of all four tires. It rose again as a machine attached to a tall green cylinder filled the tires with nitrogen. The machine then deflated and reinflated his tires again under the watchful eyes of Frank McPartland, 20, an intern with the city. The deflation-inflation is done twice to ensure a proper fill.
The process took about 20 minutes, ending with McPartland placing symbolic green valve stem caps on Anzalone's vehicle.
For now, the free tire-filling service is available by appointment to St. Peters residents only. Darling said city officials are trying to figure out whether they can offer the service to motorists outside the city.
Darling said the city already has been using nitrogen in its fleet vehicle tires for about a year. He said officials are collecting data to measure its effectiveness.
The city already had one nitrogen machine for its vehicles, and officials budgeted $43,000 for the new public system.
Darling said city staff will run the station for now. He said more than 200 people have scheduled appointments, filling most of the slots available in May.
The city would like to have 10 volunteers who can operate the station and talk about the program, Darling said.