How to get track textures?

[xopotl]

I'm currently trying to make a winter-skin for Spa-Francorchamps, but I'm having a hard time figuring out what textures the track uses. I've got most trees covered because I "cannibalized" another mod, but for stuff like grass, etc. I'm totally in the dark...
Is there a convenient way to figure this out?

 

[Albert McSaltens]

3dsimed

 

[xopotl]

Thanks for your concise, but very efficiënt and clear answer... Cheers!