My daughter is in 11th grade. We just bought a 1955 selmer centered tone Bb clarinet. It has the original selmer mouthpiece that came with it. My question is...What vandoren reed works best with a vintage clarinet? She currently used a size 3 to 3.5

Thank you for taking the time to answer my question.

That would be very individual and depends on the facing of the mouthpiece, her embouchure, how much she plays, etc. I'd start with a 2.5 and work up until she is getting a clear tone (not stuffy or hard to play) throughout most of the range, with altissimo speaking clearly and not playing flat, as it will if the reed is too soft. Many stores sell those reeds as singles, so a little experimentation shouldn't break the bank. If she isn't thoroughly satisfied with the feel and tone, I'd consider a different mouthpiece or brand of reeds. Its a very individual thing, and a Selmer mouthpiece with Vandoren reeds might or might not be the best fit for the horn. Feel free to touch base with me if you need more suggestions...