Optimal bike tire air pressure typically runs from 80 to 130 pounds per square inch for narrow road tires, 30 to 50 psi for mountain bike tires and 50 to 70 psi for hybrid tires. The amount of pressure needed also depends on the rider's weight and equipment.
Bike mechanics suggest that bike tires should have a 15 percent drop on fully loaded bikes. Over-inflated tires tend to have less traction than properly inflated tires and give a harsher ride. Riders should lower tire pressure when biking on wet roads. Tire pressure should never be higher than the pressure recommended by the manufacturer and typically listed on the sides of the tire.