Motorcycle/scooter tires will tend to develop a "flat spot" if they are left in the same position for a long time. These flat spots will usually disappear after 5-10 miles of riding but those 5-10 miles can be very disconcerting because the bike won't feel right.
Sometimes the flat spots are permanent and the tire will need to be replaced. In addition, if a tire loses pressure, which it will in colder temps, the loss of pressure and the weight of the bike resting on the tire can do some real damage. Why take a chance?