http://www.motorcyclistonline.com/escape....03.html
I've successfully used this kit to repair nail holes in two different rears and ran them until I needed another tire. I believe its the size and construction of these particular 'worms' they use. But your problem may be that you have too big of a hole to safely patch, plug or otherwise repair. As the object punctures the rubber and works its way inside the core, it slices thru valuable belts, strands, cord, whatever, which weakens the tire's construction. Small holes don't do too bad of a job on the cord but a screw, broken glass, or a head first nail may have ruined it. I'd have to inspect the inside before I'd risk it just because of its head first placement.