If I connected my tub drain to the sink drain with the .25 per foot slope, would it be best to re-vent or is it perfectly okay to leave wet vented. My wife is realy concerned about toxic fumes entering the home.

Nwptsailor

It depends on how close the tub is to the lavy drain. If the tub is within three or four feet , it will drain and vent but it is not exactly proper. A tub drain functions best when it is in a two inch pipe & is close to a conventional vent. Your lavy is probably an inch and a half pipe.