From the 206BIII Pilot Transition Manual, P1.4, Figure 1.3 Principal Dimensions on
low skids the height to the tip of the front main blade raised against the dynamic flap restraint: 11ft 7.5in.
From the Flight Manual Supplement FMS-13 Hi-Skid Landing Gear Tubular Type Page VII, 'General Information',
The Hi-Skid Gear when installed will provide an approximate 13 additional inches of ground clearance etc
So it should then be a fwd tip clearance with blades tied down at the tail boom of 12ft 8.5in.
Obviously you can reduce this by tying the blades level, but by how much I don't know. Different skids will vary, Aeronautical Accessory skids may be different to Bell, and so on. But hopefully that gives an idea.