Can I legally rent and ride a scooter in Da Nang with a Thai motorcycle licence, and do I need an IDP?

One commenter jokingly suggested it's cheaper to fly to Bali, buy a 5-year license there, and then ride in Vietnam with it — but be prepared to argue with police if stopped.

For scooter rental and riding, use a full 5-year Thai motorcycle licence rather than a temporary licence.

Do not rely on the national licence alone: carry an International Driving Permit (IDP) together with your Thai licence.

Avoid relying on a 2-year temporary Thai licence for riding in Vietnam; the 5-year licence is the appropriate document.

Traffic in Da Nang is not necessarily harder than Phuket, but the riding style is different; for a 10-day trip, rent a scooter only if you are comfortable in busy Southeast Asian traffic.