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Tire pressure is given either as maximum pressure or as a pressure range. How a tire performs under different terrain or
weather conditions depends largely on tire pressure. Inflating the tire to near its maximum recommended pressure gives the
lowest rolling resistance; but also produces the harshest ride. High pressures work best on smooth, dry pavement. Very low
pressures, at the bottom of the recommended pressure range, give the best performance on smooth, slick terrain such as
hard-packed clay, and on deep, loose surfaces such as deep, dry sand. Tire pressure that is too low for your weight and the
riding conditions can cause a puncture of the tube by allowing the tire to deform sufficiently to pinch the inner tube between
the rim and the riding surface.
CAUTION: Pencil type automotive tire gauges and gas station air hose pressure settings can be inaccurate and should not
be relied upon for consistent, accurate pressure readings. Instead, use a high quality dial gauge.
Check inflation as described in you’ll know how correctly inflated tires should look and feel. Some tires may need to be
brought up to pressure every week or two.
Some special high-performance tires have unidirectional treads: their tread pattern is designed to work better in one direction
than in the other. The sidewall marking of a unidirectional tire will have an arrow showing the correct rotation direction. If your
bike has unidirectional tires, be sure that they are mounted to rotate in the correct direction.
2. Tire Valves
The tire valve allows air to enter the tire’s inner tube under pressure, but doesn’t let it back out unless you want it to. There
are primarily two kinds of bicycle tube valves (actually, there are other designs, but they are seldom seen in the US any
more): The Schraeder Valve and the Presta Valve. The bicycle pump you use must have the fitting appropriate to the valve
stems on your bicycle.
The Schraeder is like the valve on a car tire. To inflate a Schraeder valve tube, remove the valve cap and push the air hose
or pump fitting onto the end of the valve stem. To let air out of a Schraeder valve, depress the pin in the end of the valve
stem with the end of a key or other appropriate object.
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