Repairing a tire is possible when:
There’s a puncture in the tread area and it’s less than ¼ of an inch (6 mm).
No other gashes or cuts are longer than ¼ inch.
The tire’s steel belt has not been damaged.
No earlier repairs have been done in the same area of the new puncture.
The extent of damage caused by what appears to be a simple puncture is determined by taking the tire off the wheel and checking for damage inside. In some cases, there is more damage inside the tire. At that point, your mechanic will tell if it can safely be repaired. If you find yourself in a situation where the tire is patched, have it properly repaired or replaced as soon as possible. It’s not worth having a serious accident with injury or even death simply because it was inconvenient to take care of.
Don’t drive on a tire that is going or has gone flat! You can cause more damage leading to:
Damage to the valve stem
Ripping the tire or separation of the tire and rim
Tire failure