thanks Visual, What you are suggesting is to make the tire tread pattern out of mesh, ............. rather than paint a tread texture pattern mapped onto a low poly mesh.
Using this hi-poly mesh method will result in each tire being several thousand polys, but since it is for a game model, you can't use that many polys ............ so the only choice therefore to make a low poly tire mesh and add a tire tread texture along with a bump_map, spec_map and cube_map to finish it off.