According to the BJCP 2015 Style Guide, a Weissbier should be carbonated to to 2.9-4.5 vol of CO2. I am drinking one I brewed now, and I carbonated to 2.6 vols, and it is well carbonated, with a good head, but is not strictly to style. That being said, the next time I brew it, I will carb it to 3.2 vols. Not sure I want to go over that amount, using the bottles I bought from the LHBS. I am a bit nervous about bottle bombs and gushers from too much pressure in a bottle. If you are kegging, you can probably go higher with no problem.