VISA: General Information - สถานเอกอัครราชทูต ณ กรุงลอนดอน
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where, i know for a fact i have entered Thailand with 3 months left on that passport, came in for weekend from Singapore. Only issue was airline showed them my return ticket and my Singapore long pass card and not an issue
For motorcycle stuff better ask in this group. But guessing when you enter by road it will ask for the plate number (same as malaysia and singapore) there are other things to do with insurance and stuff as well but check with this group for latest info on that