Honda 2005 VTX1800C Owner's Manual page 147

Tires
The recommended ''cold'' tire pressures
are:
VTX1800F
front
rear
138
Servicing Your Honda
33 psi (225 kPa ,
2.25 kgf/cm )
42 psi (290 kPa ,
2.90 kgf/cm )
VTX1800C
front
rear
includes the weight of the rider,
passenger, all cargo & all accessories
33 psi (225 kPa ,
2.25 kgf/cm )
33 psi (225 kPa ,
2.25 kgf/cm )
with less than
200 lbs (90 kg) of
added weight
36 psi (250 kPa ,
2.50 kgf/cm )
with more than
200 lbs (90 kg) of
added weight