I am in the planning stages, trying to firm up a site in the next week. So definitely have zero expertise but would share the following observations based upon the tours I have taken:
If the tour is free and no free tasting, the majority of the tour takers are going to buy drinks. They are in a distillery because they like and drink alcohol.
If the tour, paid or unpaid, includes a free tasting, your bottle sales will probably be higher if your product is quality. Your drink sales will probably be lower.
Your Walk-ins (non-tour takers) are likely to be mostly repeat customers who are there specifically to buy your bottles. (assuming you are not in a heavy foot-traffic tourist location)
Hopefully some of the veterans on here will give you some experienced knowledge. Best of luck in this venture.