I did a little research, and it depends on which wheat malt base you want to use. White wheat malt is the only one to have enough diastatic power to completely convert itself (130%). German wheat malt is really close at 95%, dark wheat is 10%, and Belgian wheat malt is 74% for the set of malt analyses that I looked at. It is suggested to "Use with a highly modified malt to insure diastatic enzymes. (http://www.foamrangers.com/malts.html
)" though the same people list that common German Weizens are up to 70% wheat malt. Hope that helps.
Look at the malt analysis of the wheat malt you plan to use. If it is 100% or more it should convert itself in theory, though most things I see when I search around suggest using at least some base malt in the mash with high enzymatic power.