The tone on my C string is poor - it kind of bends in pitch if you exert (fairly normal) pressure on it. My teacher's suggested trying just changing that one. What's a good bass string on the viola? I can't remember what the luthier put on originally - not dominants, I know.

I can't decide whether to just change the C string, or whether to get the lot changed while I'm messing about.

What do you think?

I have heard many times that 'generally speaking' it is better to have all strings the same (ie: all dominant, but I do know that many people on this forum who have dominant have changed the E string on violin).
any experts to advise? I am sure they will in good time.

Generally if one string (other than the e string on a fiddle or a on the viola) goes, I change the whole lot so that the new string doesn't stand out terribly.

On viola I like Helicore or Larsen, but if you take it back to your luthier and have him / her change the strings for you then they'll choose something that's suited to the instrument.

Allan