It doesnt look like anyone has really addressed his question.... ALL radial tires not just Z rated have plys of steel meesh and polyester making a carcus. when a nail or other object punctures the tire it tears the carcus causing a week spot in the tire. If you do not drive the car hard such as racing autox roadracing 100mph+ speeds or extreme braking you should be OK to patch it as long as the hole is not near the sidewall. I would go to Sears or Tire Kingdon or any place that has patch-plugs they remove the tire from the rim and put a plug that has a patch built onto the buttom of it to assure leak free and tear free pluging.