lens cap for Yashica Minister D

I have a Yashica Minister D which needs a lens cap. It has a dent in the filter ring so I will need to get a push on type cap. And since I live nowhere where odd sized caps are available I will have to order it from B and H or somewhere similar. So before I do I was wondering if anyone can confirm that a 48mm push on cap will fit a minister d? I'd rather not order it and find it does not fit. thanks!

in lieu of finding out specifically about the minister d I guess I could at least ask the following:

are press on lens caps sized by the outer diameter of the filter ring, or by the filter size? In other words, if the lens accepts 46mm filters (and therefore a normal 46mm lens cap), would the appropriate press on cap for such a lens be designated 46mm or 48mm?