How is a wheel bolt pattern measured?

["Steven Volpp" <volpp@netdoor.com>]

I need to order some new wheels for my trailer.  I just realized I do not
know how a bolt pattern is measured.

Can someone please tell me?

///          autox@autox.team.net mailing list
///
///  To unsubscribe send a plain text message to majordomo@autox.team.net
///  with nothing in it but
///
///     unsubscribe autox
///
///  or try http://www.team.net/cgi-bin/majorcool
///