With the largest civilian fleet in the world—more than 214,000 vehicles traveling more than 1.2 billion miles each year—the U.S. Postal Service knows a lot about vehicles and tire pressure.

Summer driving season is approaching and the Maintain Tire Pressure postage stamp helps remind motorists that proper tire pressure can help improve gas mileage. It’s one of the 16 Go Green Forever stamps issued by USPS.

“The Postal Service is building a culture of conservation that benefits our workplace and the communities we serve,” said Emil Dzuray, acting chief sustainability officer. “We believe the tried and true tips our letter carriers use to conserve fuel when delivering mail can also help motorists during summer driving season, and year round.”

Fuel conservation tips:

• Use air to save fuel—Underinflated tires can increase fuel consumption by as much as 4 percent and lead to excessive tire wear. Properly inflated tires are safer and last longer.

• Don’t idle—Idling uses at least a half gallon of fuel per hour and releases excess carbon dioxide and other pollutants into the atmosphere.

• Drive the speed limit—Speeding is dangerous and, at highway speeds, fuel economy drops for every one mile per hour driven over the speed limit.

• Make gradual starts and stops—Quick accelerations consume more fuel than gradual starts.

These fuel conservation tips are part of a comprehensive strategy USPS is using to meet its goal to reduce vehicle petroleum use 20 percent by 2015.

The Go Green stamps can be ordered online at usps.com/green.