A puncture can usually be repaired if it's smaller than a quarter inch across, sits in the tread's central area, and the tire hasn't already been patched there before. Damage to the sidewall, a puncture near the shoulder, or a tire run flat for any distance means replacement, not repair.
Why does the location of the damage matter?
The tread's center third is backed by steel belts that hold a plug and patch combination securely. Move toward the shoulder or onto the sidewall and those belts curve away, so there's nothing for a repair to grip — the rubber flexes too much under load and the patch works itself loose, usually without warning.
A shop checks this from both sides: a plug alone seals the hole from outside, but the patch bonded to the inner liner is what actually holds air and keeps the steel belts from separating further.
What disqualifies a tire from repair even in the right spot?
A second puncture closer than roughly an inch and a half to the first, or a repair overlapping an existing plug, usually fails inspection — there isn't enough intact rubber between them to seal reliably.
Running on a flat tire for even a short distance can separate the inner liner from the belts in a way that's invisible from outside. That tire gets replaced, not patched, regardless of where the nail went in.
Does the type of tire change the call?
Run-flat and some high-speed-rated tires are built with reinforced sidewalls that manufacturers generally don't approve for plug-and-patch repair at all, even with a textbook puncture in the tread. The construction that lets them survive a flat without air doesn't tolerate a patch the same way a standard tire does.
Can the same tire be repaired twice?
Only if the second puncture is far enough from the first repair to leave solid rubber around both patches. Two punctures close together usually mean replacement instead.
Is a repaired tire as safe as a new one?
Done to standard — inside patch plus plug, in the tread, with no prior nearby repair — yes, it holds air and handles normally. It's the location and history of the damage that decide whether a repair is even an option.
Will a repaired tire need rebalancing?
Yes. Removing the tire from the wheel to patch it from the inside resets the balance, so it gets rebalanced before it goes back on the car.