Just found out today that you cant do this with the viper?

[Chikane_GTR]

The 2013 SRT Viper in Red With white Strips Why do the strips change to black when you repaint the Car?? find it funny that they cant give you a simple feature like strip color choice. And no i'm not crying over this and its not a feature request It would had been cool with this car. Plus i'm sure the viper is not the only strip car with this problem

 

[R5]

You can get darker reds which give white stripes, I can't give exact examples but I believe Jaguar's Italian Racing Red does this.

 

[GTR365]

My experience repainting cars with existing racing stripes has been, regardless of which original stripe color, the stripes typically become white with a darker color body paint & black with a lighter color.
I sometimes prefer this not to be the case & have found that repainting with some blues, greens & reds provides nicely low contrast black stripes.
A pleasant, notable exception is the Shelby Series One. The stripes seem to coordinate with the repainted body color.
I also noticed a few cars (maybe Ford GT) which become striped when repainted even though I purposely purchased the non-striped variant. Also I noted, again unpleasantly, that the Ford Mustang Mach 1 lost striping when repainted.
Hope this helps.