Hi SanSingh,

> Why does my tyre tread design crowd together when I use flow?

That's probably because of using the "Rigid" option with Flow combined with having a too wide base plane. The "Rigid" option for flow does not deform the objects, it only moves and rotates them to a new position and the new position is based on flowing just the bounding box center point. When this is combined with having a wide surface mapping onto a narrow surface that "wide to narrow" mapping will cause the objects to come closer together and overlap each other.

> Why is my tyre named 'Joined Surface' and not just 'Surface' like in the tutorial? Could this be where the problem lies?

It's because the profile curve you revolved was made out of many different segments rather than just one single segment. You could use the Rebuild command (http://moi3d.com/3.0/docs/moi_command_reference10.htm#rebuild) on your profile curve to make it into a single segment before revolving it to have just a single surface but I'd think you're probably fine with the current multi-face structure since the center tread area of the tire is not split up itself, it's just split between treads area and side wall area which you probably want to flow with separate steps anyway.

- Michael