To Michael,

If you look at my thread on the tire, the one that follow the edges of the of the tire, i tried to edit so i can lower the 2 points so the thread seem to be finishing into the tyre instead of being, i would say, square/rectangle shape.

I found that after extrude the piece that was trim, if i click on show points, it only show point from the curve at the bottom of the piece that was extruded but no point on the top part. (hope you understand - if not i will show you what i mean when i will be home). i think i did try to separate but i couldn't play with the part, unless i wasn't doing a functionn first ?? o.O

Cold