Honda VTX1800R Owner's Manual page 123

Tires
We recommend that you visually check
your tires before every ride and use an air
pressure gauge to measure the air pressure
at least once a month or any time you
think the tires might be low. Even tires
that are in good condition may lose one to
two psi per month if not checked and
adjusted regularly.
Cast Wheels: Tubeless tires have some
degree of self-sealing ability if they are
punctured.
However, because leakage is often very
slow, you should look closely for
punctures whenever a tire is not fully
inflated.
114
Servicing Your Honda
Always check air pressure when your tires
are ''cold'' –– after the motorcycle has
been parked for at least three hours. If you
check air pressure when your tires are
''warm'' –– even if your motorcycle has
only been ridden for a few miles –– the
readings will be higher. If you let air out
of warm tires to match the recommended
cold pressures, the tires will be
underinflated.