@shanr You can either create tyre segments as spikeyxxx did (see his first picture on this page) and duplicate them with the help of an Array Modifier and a rotated empty as object offset or you can, as I did it, trace the outline of one tread piece on the tyre surface by extruding an edge while in “Face Select” mode and snapping of “individual elements” turned on (your viewing direction determines the projection direction). Then add a solidify modifier for the tread thickness und a subsurf modifier for smoothing the tread outline (additional edge loops will reduced the “rubber look” of the treads in my pictures above). I duplicated the tread piece with an Array Modifier and a rotated empty. The tread pieces on the inner side of the tyre a just mirrored copies of the tread pieces on the outer side of the tyre. For further details take a look into the files under the links on Kent’s piece selection sheet.
