Use the little pipette to get the material from the object. Get to the tire sidewalls material. Set the diffuse field to black. The material editor is very important for rendering. Learn this sh*t.
1.) There are premade scenes for 3d studio max. http://ds-autos.digiserv.net/scenes/lfs There is also a cmx importer for 3ds but i dont have a link, just search. Importing 3dmodels back in LFS is NOT possible. (for normal human)
2.) Skinning glass in LFS is not possible. You can skin windshield banners on GTR cars. It may be possible to make a texture for the usage for glass materials when you render skins, so you might get the effect you wanted, but not ingame LFS.
Skinning has nothing to do with pasting ugly fake lights on an XRT. I'll give constructive critism if I see that something constructive is going on. At least preview screenshots from cmx viewer are a step in right direction and dont use a bold XXL Comic Sans MS Font. Just dont do it.