Stud Tyres - fixing the spikes on new tyres
I just bought these tires for Scottish winter, will chuck them on pretty soon. I think the idea for this 40km is to break the studs-in, to settle them into the tyre. 
So I would run them on medium pressure: the tyres are not overinflated, but also not on low pressure, sot the studs are engaged, but not 100%.