@Kevin *****
if you enter Thailand with a Thai tourist visa you bought before you fly to Thailand from a Thai Embassy or Consulate, you are STAMPED in for 60 days. And that can be extended for 30 ADDED days at your local Thai Immigration office for 1900 Thai baht. = 3 months.
Plus you can do a maximum of 2 LAND BORDER BOUNCE entries into Thailand EACH CALENDAR YEAR. AND Each one can be extended for 30 ADDED days at your local Thai Immigration office.
That's an extra 2+2 MONTHS
+ 3 with tourist visa = 7 MONTHS maximum stay in Thailand.
To stay longer... suggest you get the METV multiple entry tourist visa in your home country. With planning it can get you up to 9 months stay in Thailand with a few simple land border crossing entries into Thailand.