HOW TO OBTAIN A THAI DRIVING LICENCE
To obtain a Thai driving licence from the Thai authorities you will need the following documents:-

PASSPORT (original plus a copy)
VALID NON-IMMIGRANT VISA
LETTER FROM THE EMBASSY (confirming residency)
DOCTOR’S CERTIFICATE
VALID DRIVING LICENCE
TWO PHOTOS (1”  x  1”)

You may have to sit a driving test and pass a written test on traffic signs.  [...]