There are nails, and then there are nails. This one was huge: way beyond 16-penny size. It went right through the tread block and proceeded to puncture the Kevlar in this new-style Goodyear MT/R. The MT/R is tough, to be sure, but it's not impervious. A Safety Seal tire plug was inserted where the nail had been, and the tire was re-inflated. Problem solved.