This Slime Chrome Pencil Tire Gauge is the ultimate solution to checking your tire pressure on the go. Measures 5-50 psi. You can improve your gas mileage by around 3.3 percentage by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.4 percentage for every 1 psi drop in pressure of all four tires. Properly inflated tires are safer and last longer.