Rob,
In the UK, in that former life before the WPP relocated me here
, I had a side job working for the local tyre shop doing re-grooving using the tool Bob described.
They had made up a jig that enabled you to mount a tyre onto it and stand and push the tool through the pathways of the grooves, as you ran out of tyre one stepped on the pedal and that would release the brake and allowed the tyre to rotate a ways and voila fresh tyre to work with.
It was a mindless smelly job best done with a fan behind you off to the side a bit.
I did it while saving for airfare to Ibiza, that den of vulgarity in the Med.
A good entry level job for the youth of today.
R