Determining drum head size and rim size?

Ok. This may be dumb question, but how do you determine the what size head and rim will fit a particular drum? I want to buy them online so I don%26#039;t have a way of visually determining the sizes I need. I need to buy a bottom rim and head for my 10%26quot; tom. Does the size of the drum (width) correspond to the size head and rim I need? For example, a 10%26quot; tom would take a 10%26quot; head and rim?





Any help would be great!





Thanks!