How much should we tip a driver on a private tour?
For a private tour, $5 tip per day for the tour guide and half of it for the driver is acceptable. If you are pleased with the service provided and find the trip enjoyable, some more dollars might be a good motivation and they would be happy to receive because they are deserved to it.
Remember: 50,000 ($2.5) and 100,000 ($5) are considered big notes in Vietnam!
Read more about Tipping culture in Vietnam.