A: The exceptions to the left-hand driving rule are Vietnam, Laos and Cambodia, all having been under French domination at one time. Anyone who is worried about the driving rules in Thailand shouldn't be. International rules are generally accepted. There is a speed limit of 80 kmph in town and 100 kmph on open roads. A driver must always be in possession of a valid driving license from the country of origin. An international driver's license is not required. What is needed is the vehicle's Registration Book. It's a great way to travel, behind the driver's wheel, driving one way and returning by air the other way.