I tried some calculations to answer that (https://news.ycombinator.com/item?id=12589228 https://news.ycombinator.com/item?id=12589228). Just taking into account

I tried some calculations to answer that (https://news.ycombinator.com/item?id=12589228 https://news.ycombinator.com/item?id=12589228). Just taking into account the parent body, Mercury should experience a much more pronounced variation in its tidal gradient than does Io. However, I suspect it's the interaction with the other moons that make up for it in Io's case.