Tacks = bad. Damned Antifa types, or whatever they are.
i wonder if they'll have to start sweeping ahead of the race with those magnetic rakes like roofers use, in addition to ski nets, to moderate the risk and insanity. I'm half surprised JV hasn't already suggested it.
Tinker = colloquial British English for mischievous youngster. Not to be confused with Tinker Tailor Soldier Spy.