Tyre pressure should be measured when the tyres are cold, every 15 or so days.
A cold tyre is a tyre which has not been used for more than 2 hours or has travelled for less than 3 km at a moderate speed.
Pressure increases with temperature. For a measurement with a hot tyre, deduct 0.3 bars to have the equivalent pressure for a cold one.
Correct pressure is essential for safety, comfort and the life expectancy of the tyres. This is why it is important to comply with the pressures recommended by the manufacturers.
An over inflated tyre causes excessive wear of the central tread and a decrease in grip due to a reduction of the surface of contact with the ground - also causing greater instability of the motorbike at all speeds. Moreover, it will absorb unevenness of the road less effectively, leading to a decrease in comfort. In the event of extreme over inflating, there is a risk of the tyre bursting.
An under inflated tyre will wear out quickly, and often irregularly. Deformation of the tyre responding to mechanical stress will be exaggerated, and this can cause deterioration in the tyre's carcass which can lead to bursting. These deformations will also lead to overheating which may take the tyre above its operating temperature and thus reduce grip and cause or speed up deterioration of the tyre (the carcass, tread and properties of the rubber). Under inflating also expresses itself through heavy steering and instability of the bike (weaving, a tendency to straighten up excessively whilst slowing down on bends, etc).