I realize that the original post approx 9 years old, but felt that I could provide some information about plugs and patches for tubeless tires. Most people buy the red or black colored string plug kits ( Camel, Victor, etc ) which I feel would be ok for lawn mower and similar non-highway equipment. Some posters stated that they have been told how inferior the plugs are compared to patching the tire from the inside. I have approx 35 years of tire repair experience and offer the following advice in the name of safety and economics.
As I stated above, the string type is ok for off road equipment if you are not out in no-mans land, but other than that I can only recommend leaving that stuff on the shelf at the store. A good quality tubeless tire patch or plug that is properly installed in a tire injury can last the usable life of the tire providing the tire was not ruined upon going flat and driving on it, and the injury is not too large to safely hold the plug in the tire.
Go to Napa or other quality automotive stores and buy the professional plug , patches, and insertion tools. The professional type plugs and patches use a chemical cement, and plugs and patches manufactured specifically to react with the chemical cement. When installed properly these plugs and patches are basically cold vulcanized to the tires. Properly installed and given at least 30 minutes to cure after installation, a baby gorilla would have a tough time pulling the plug out. I have never had a plug that I inserted into a tire come out. I do agree that a patch placed inside the tire over the plug can sometimes prevent air leakage from small particles becoming impacted and worked in along side the plug and tire (and this is very rare)..............Now that I am done with my mini rant, I will tell you how I was trained by a factory rep on the proper way to plug tires using the quality materials.
Plugging a tire:
1) Located and remove offending item causing the flat or slow leak. A tub of water or soapy water in a spray bottle will detect the leak by bubbling at the injury location providing there is, or air can be put in the tire.
2) After removing the item causing the leak, determine if the injury hole is small enough to be plugged.
3) Insert the spiral looking awl or even the rasp looking ones after dipping the tool in the liquid tire buffing solution. Be very care and do not use near open flames or sparks or while smoking. The buffing solution is extremely flammable just like some of the chemical cements. Do this a couple times to clean any oils or other debris from the hole. Do this while there is at least a small amount of air in the tire to blow dry the solution.
4) Next, get the proper sized chemical plug inserted in the insertion tool. With air still in the tire, dip the spiral or rasp tool in the chemical cement and insert it in the hole and push it all the way in, then pull it out. Do this at least 2 times turning the tool while it is going in and out. This not only applies the cement, but will also open up the hole to at least the minimum size to accommodate the smallest plug. >>>>>>CAUTION>>>>> Always wear safety glasses not only because of the obvious reasons, but also to keep the stringy chemical cement from getting in your eyes while the air pressure from the tire is blowing the excess out.
5) Dip the entire plug into the chemical cement and briefly allow the excess to drip back into the can. Make sure there is at least 30 psi in the tire. Next, insert the plug following the directions that came with your insertion tool.
6) After the plug has been successfully inserted, air the tire up to the proper psi, and let the tire set for at least 30 minutes.
7) After approx 30 minutes use a razor blade or other sharp tool to cut the plug off flush with the tire.
You have now made a tire repair that is highway worthy and should last as long as the rest of the tire does. It should be noted that it is possible for some inferior chemical cements to turn gooey if the tire encounters extreme heat. People living in the warmer climates may want to consider using a patch on the inside as well.
Even though the chemical patches and plugs along with the related tools will cost you more initially, you will eventually recover the cost by not having to replace a perfectly good tire after the old string stuff popped out causing damage to the tire, and it will save time by not having to repeat same tire repairs.
I hope I did not offend anyone who believes in the string products. I am just concerned about others safety who are/were not aware of other safer quality products.
