Nah you dont buy a new tyre lol, we just grind all the nobbles off really old tyres, i have no idea how it grips, but it just does, i cant tell the difference between a bald monty and a brand new monty for grip, but the bald ones are alot grippyer, i dont ride in the wet, or in comps so i dunno about that, cant imagine it working though, ill try get a pic tomorrow.