As far as I know they both share the same mapping, so basically you can't. All you could try to do is keep altering it until you've got the minimum possible on the dash while still getting a decent look on the externals.
Quote from Darkone55 :Hi there, Here are my two latest updates of the reflection textures. Please read the readme.txt (in the zips) carefully! They both have textures of 512*512 (which is twice the original size). The first version (reflecttex_darkonev3_1.zip) contains textures that are supposed to be close to real. So they have clouds on it and everything. The second version (reflecttex_darkonev3_2.zip) contains textures that are supposed to look nice. Not too busy, the colors less real but nicer.. Both versions cover all tracks, so, on all tracks you will have higher res reflections. Oh, and the zip differ in size a bit, but the size of all the textures are the same. Enjoy them! What setting did you use to shoot the screen shots, they look unreal!