When you notice you have a tire that is very slowly going flat, you have two options. Put more air in the tire to pump it up again, or head into a station for tire repair. You might be able to perform with perfunctory action. If you opt to make some repairs on the tire yourself, you are going to need to do the following.
Find the Leak
First and foremost, it is necessary to find the leak in the tire. You cannot repair what you cannot see. Tire repair shops find the leaks in the damaged tires by inserting them into a tub of water, inflating the tires, waiting to watch for bubbles, and then rotating the tires another ninety degrees and trying to inflate the tires some more. The tire technicians are looking for air bubbles escaping through a break or hole in the tire when the tire is sitting in water and being inflated. When they spot the bubbles, they can also find the exact location of the leak. You can do the same if you have an air compressor and a kiddie pool in which to immerse the tire while attempting to inflate it with the air compressor.
Patch the Leak
Patching the leak gives you two options. You can patch the leak from outside, or patch the leak from inside. If you patch the tire from outside, you have to adhere a special tire patch using a tire patch kit. Make sure your patch fits the leak area perfectly, or it could peel back and fall off while your car is rolling down the road. Then follow the instructions for applying the exterior patch to the letter.
If you patch the tire from within, you will need to allow the tire to go completely flat. If you are in a hurry, let the air out yourself by depressing the valve on the tire's air port. If you can, press the remaining air out by pressing on parts of the tire. The interior patch for tire leaks involves a special can of aerosol rubber. It has to be injected into the air port/valve of the tire via the hose connection on the can of patch. Make sure you completely empty the can of patch into the tire. Spin the tire for a bit, and then refill it with air. Do not drive on this tire for the time required in the instructions in order to give the patch enough time to fill the crack or hole from the inside and solidify.