Track creation with btb.. Help!

[fabri1998]

I have bought btb pro to build tracks... I'm going to build the track in which there will be the World Cup kz1 : Le Mans.
But I don't know how much large must be the track (track width) ... The valours start form 1 to 6 but without unit of measurement (no meters .. Nothing only a number) ... If someone use btb can tell me which number  must I set on track width? I copied the track from google maps but is too long and I don't know how must I do
Thanks