I may get bashed, but if you tuck your boots you may think it looks like this
when it really looks like this
You are much safer with this look.
If you aren't a daily rider, or a rider at all, tucking will look silly 9 out of 10 times. it just will. Some will disagree. Untucked is easy to pull off anywhere, anytime. Tucked only looks good on a bike or if it just comes natural and looks effortless. If you have to ask, then I wouldn't tuck or go too slim.