Those field types are not meant to be used for such large lists. You'll hit server input limits trying to save that field. When you need that many options you should be using CB Query Field and its Query Select type so you can build a list from a custom database table. It can also support making it searchable so it's a lot easier for your users to use as 249 dropdown options is horrible usability with a standard select. If you insist on still doing this contact your host and have them increase the server input limits.