How do you adjust the Siege Tank Circle Range of Fire Model?

You mean the graphics, or the size? The graphics are stored in an m3 file, you can export it from the mod mpqs and edit it in 3ds max. If you need a more detailed explanation let me know, I'm pretty tired right now is all ;0

Look for the Actor object called something SiegeTankRange. It will be similar in type to Pylon's energy radius and the Sensor Towers radius. You can then set that to whatever size or model you require.

I meant the size. Thanks for the help.