Attached Link: http://www.chez.com/litst/index/downloads.htm

Kaom, you did use the torus function, right ? If you look at my tire, you'll see that i used an extruded circle instead . This technique has the advantages to let the circle stay round and to give smooth edges ( i'm at 500% fidelity for close-ups ) . It doesn't work in any case, but it's good enough for a tire . I think i can guess why you get sharp edges with torus extrusion . When you increase the surface fidelity, Carrara makes the cross section smoother, but not the extrusion path . The torus is based on extrusion, so that's why ... It's just a guess and i may be wrong, though . And it doesn't explain why toruses get square . If you really have to convert your shape to the vertex modeller, then follow this : - convert it using a high fidelity if it helps . But it's not necessary, since the mesh will be subdivided . - in the VM, select all and weld with a custom tolerance of 0 . This is to get rid of some vertices that are doubled when you convert a spline to vertex . - Smooth all - Save your file, close it and reopen it . This will reset the normals . - Now you can subdivide the mesh as much as you want . If you have Carrara Studio, then prefer Amapi to subdivide the mesh : the subdivision algorythms are much better . I'm joining the link to the tire file again, for those who'd like to download it . litst litst.@freesbee.fr http://www.chez.com/litst/