For a newbie, you're pretty good with your model.
About the Textures.
Reflective textures consist of two things: Regular textures and Alpha Channels.
[creation]
First, create a texture file and save it in the "texture" sub-folder of your model's main folder. Make sure that the dimensions are a power of 2's [ex: 512x512 pixels, 1024x1024 pixels, etc.]. Not only that, make sure that your file's name has a suffix *_t at the end [ex: My_Texture_t]. This "t" is important.
Now, do whatever you want with the file [adding texture parts for the wheel, surface, etc.].
Now, make a copy of that same file and rename it to "My_texture_Alpha".
Open that file and change it to black-and-white settings. You have created an alpha channel. In an Alpha Channel, the amount of greyness will indicate how reflective a part will be when rendered in FS.
Examples:
Black = totally reflective [for mirrors, chrome parts, etc.]
Grey = semi-reflective [for aircraft surface and such]
White = no-reflections [for tires, seats, etc.]
Basically, the darker greys have more reflectiveness than the lighter greys. Now that you have your alpha channel in black and white, you can make any small changes if needed.
Now you need DXTBmp. You can find it by making a "google" search and type in "DXTBmp". You should find the website [it's obvious] on the first page of the results.
After downloading and installing it, do this.
Open the program and click on "Load Normal Image" in the "File" menu. Find the main texture that has the "t" as the suffix [My_Texture_t]. When you open it, you should see it on the main window.
Then, go to the "Alpha" menu and click on "Import Alpha Channel". Search for the file that has the greyish parts applied [My_Texture_Alpha] and click "Open".
Then go the "File" menu and click on "Save Extended Image". Were it says "Save as type", choose "DXT3 with Alpha". Then, save the file as "My_Texture_t" in the same location as the normal image and click "Save". Click "Yes" to replace.
NOTE:
Make sure that you apply the main texture [My_Texture_t] to the Gmax model BEFORE you do applye the textures.
After you are done with the alpha channel and such, go to the material editor of the applied texture and click on "Reload". The Gmax model should now appear greyish. This is natural.
The reason why I say that the "t" is important is that IF you don't add that single "t" at the end of the file name, FS will render the alpha channel that is applied as transparent instead of reflective.
WHEW!!!! That should cover it.