In general it's best to check the motor vehicle department rules (and in many cases particular states or provinces) of the country you're visiting.   If you look at the US for example, it turns out you only need to have an International Driver Permit in a handful of states, otherwise you can use your home country license as long as it's also in English (as Thai driver licenses are).   A slight shortcut would be to look at the local site of major car rental companies like Avis or Hertz in their local rental agreement requirements, they'll usually specify the driver license type required there.   

A post has been removed ... lets keep the replies civil ...else!

Its been a few years since I got my Thai license, but I only had to show my visa (O-A) and my US license, take the reaction and color test. Since I had motorcycle endorsement, I also got a license for motorbike. The only problem I had was with the Medical Donor endorsement on my US license. A bit hard to explain that if I am killed in an automobile accident that they can take out my organs for to use for others or to teach doctors????.

Where I live in the US (Oregon) you can use the Thai DL for 6 months after you move there

This topic has been discussed on TV many, many times over the years. My take on it is that an IDP is not necessary if your home licence is in English & has a photo as translating English to English is pointless. However if stopped, some BiB will ask for one, particularly in Bkk or Pattaya. Therefore, it may smooth your day (and make it cheaper) if you have one to produce.

 

However, this bit is interesting in the law quoted in an earlier post:

 

In case of a driver who is an alien temporarily permitted to reside in the Kingdom under the law on immigration may possess a driving license under section 42 bis while driving in the Kingdom. In this case there shall be accompanied such driving license with the document prescribed in the existing Convention or Agreement between Thai Government and the Government of such country for producing immediately to the competent official⁴⁵.