When you hear a person speak of the non-repair zone of a tire, they are speaking of a part of the tire that has been punctured. Most often it is likely by a screw or nail.
I can’t emphasize enough the importance of having all tire repairs be completed by a trained mechanic to do a complete and proper repair. Having good tires is so important for your safety. You want to make sure any tire repair is done correctly.
The picture below shows you the repair area (grey) and the non-repair zone (red) on a tire. If a puncture occurs in the repair zone then your technician will do an inspection of the interior of the tire. Afterwards the mechanic will decide if a repair can be completed. He/ she will look at the size and spacing of the damages to determine if the tire can be fixed or will need to be scrapped.