Trees to big

The trees in my map are taking to much space, when i try to walk near them i can't walk to close, because they are taking up more space then they need to. It's like a big circle around the tree trunk.
How to i make this "circle" smaller?

I guess you go to object editor and then edit the kind of tree you use... Make a different Pathing Map... If you understand?? :////

Well, how do i know which one to use? I'm not so good at this...