It is not unusual for a tire on a vehicle to lose air gradually over time. For that reason, vehicle manufacturers recommend checking the tire pressure regularly. When your tires lose air, they no longer perform as they should. Therefore, the federal government mandated that each vehicle in the US (beginning with the 2008 model year) be equipped with a Tire Pressure Monitoring System (TPMS) to alert its driver if a tire gets low on air.
If you notice that your tires are slightly low on air, either by the way they appear, by measuring them with a tire gauge, or by way of the TPMS, you should have them properly inflated to the manufacturer’s recommended pressure. This is not necessarily a problematic condition.
If, on the other hand, you see that a tire loses air frequently or is flat, there is likely a problem that needs to be remedied with something more than air. Same goes if you find a nail or a screw embedded in the tread.
To repair your damaged tire, a technician has three options. In each case, the wheel and tire must be removed from your vehicle and deflated. One can be performed while the tire is still mounted on the wheel. The other two require that the tire be removed from the wheel for the repair and remounted and balanced afterward.
The first repair is done using a plug to fill in a hole in the tread area of the tire where it contacts the road. A technician will remove the foreign object if it is still in place. Then, using a carbide cutting tool, the technician will ream out the hole to strip away any damaged cords or belts inside the hole. A special adhesive and a rubber plug are inserted and allowed to dry before the tire is inflated and reinstalled.
For the second option, the technician not only removes your wheel and tire from your vehicle, but also separates them from one another. The area inside the tire around the damage (puncture) is cleaned and prepped, and a patch is installed. The tire is remounted on the wheel, the two are balanced, and they are reinstalled on your vehicle.
The third and best option is the most comprehensive. It incorporates both the plug and patch methods, ensuring that air remains inside the tire and preventing contaminants from entering from the outside through the puncture. Once the plug and patch have been installed, the tire is mounted and balanced, and the assembly is reinstalled on your vehicle.