the centre vc controls the amount of slip between the front and rear axles, teh tighter it is the less slip

tarmac spec is usually between 50nm and 80 nm
gravel spec can be as high as 250nm

road versions are not too far from 50nm anyway.

but you do need slight slip in a road car so not too tight ( nowhere near kev sharp tight !)

as there are certain circumstances when there will be a differance in speed on the front to rear axles. not only that the tighter they are the hotter they run , and vc DONT like to run over approx 110 deg or they lock