I have done this before with no problems, several times.
Its almost "plug and forget"..

I had one new tire get 6 nails in it in about 2 months(lot of house construction near me). I had them all plugged, never leaked on me.

Technically a plug is a temparary fix. Not legal for commercial vehicals. You are supposed to have the tire's
hole valcanizes from the inside and rebalanced. That said,
a plug that doesn't leak is fine and if done right it will
out last the tire. A plug can be a permanent temporary
fix. Take your trip. you will be fine.

Many Years ago there was a law passed here - It used to be, probably still is illegal, for any kind of auto service station to plug a tire here in Florida. They have to remove the tire and patch it on the inside.

I can sort of see why after plugging many tires myself from the $5 kits at auto parts stores. There's a tendancy to rip more cords plugging some holes and worn thin tires just dont have the surface area to hold a plug.

bottom line, if the tire is in good shape otherwise, forget about the plug, keep an eye on the tire, but don't worry excessively about it.
John

Yes, I have had good luck w/ plugs also.

Tires have changed, and in the last five years we have been seeing ever increasing numbers of low profile, high performance tires. Many tire manufacturers do NOT permit the use of a plug to repair their tires. We have been instructed to use a "Patch/Plug assembly that is bonded to the inside of the tire. There are a number of reasons for using these. One is, the tire is taken apart, and examined for damage that often occurs when it gets run while low on air pressure. If you just slam a plug in a tire, you are assuming the tire is actually still OK, when in fact it might not be. A second reason is while the plug may seal the leak, it may not seal every layer of the tire. This can allow the air to force inbetween the layers of the tire, and litterally tear it apart from the inside. One of the most common failures that we see are seperated belts, this often happens because a plug didn't seal the entire depth of the failure.

So in short, do plugs work "most of the the time" YES, they do. Do plugs fail to work, and actually cause problems? Yes it happens. Do you want a repair that is correct and will be trouble free 100% of the time? Use a patch/plug mounted from inside the tire.

I bought a new 1988 Blazer in 1988. The first week, got a dry wall screw in the right rear. I plugged the tire and after around 65,000 miles it developed a slow leak. I took pliers, pulled the plug out, put another in and it lasted 15,000 more miles until I rotated it as the spare. Still have the truck with 214,000 miles and the plugged tire is still the spare although I've since replaced the other tires twice.
You are absolutely right about the tire should be patched from the inside. I bought one of those tire changers from Harbor Freight....maybe I'll give it a shot.
I've plugged tires on several of my vehicles through the years and for friends and family and the plug lasted as long as the tire did. I think the secret is to file the steel belt plies real good with the file tool. This keeps the belts from chewing the plug in half. Then, use sufficient cement. Afetr the cement cures for a few minutes, cut excess plug just below the tread.

To the point of other problems noted in this thread. My wife had a flat while I was out but she pulled over within 1/4 mile and called for help. The spare was installed and on getting home I decided to inspect the tire before taking it to a tire shop. I filled it with air and then started rotating it looking for any damage on the tread. Soon I found and felt a leak in the side wall, very near where the tread edge is. It was facing out and could have been punctured by a nail or the like which didn't stick into the tire. I had some plugs on hand, must be at least 10 years old and stuck one in the hole. I then filled the tire with 30 psi and put it aside. Coming back an hour or so later it was flat again, so I started looking again and found, just perceptible with the hand and ear, another leak that is near the plug, a few degrees rotation away and right at the tire rim, in fact I wonder if the flat cause the "bead" to break loose and putting air into the tire didn't reset the bead. What do you (all) think? Would it help to over inflate the tire, say to 40 psi to see if the bead resets?

Jerry:

You stated that the puncture was in the sidewall near where it meets the tread. This one can not be relaibly plugged. It is recommended that only punctures within the tread width are pluggable, and that gets questionably as the puncture location gets near the edge of the tread.

However, I have had sucesses with plugs in fairly large punctures within the tread width. My last pucnture was a flange head body bolt 3/8 dia.

Thanks, and I can say the thickness of the tire at the puncture point didn't seem to be much, I suppose just the sidewall thickness. This and the fact that there is a leak at or near the tire/rim bead may mean its time for a new tire. These tires have about 20,000 miles on them and I had expected to get 50,000 or more, so this is an early failure. Perhaps the tire can be repaired from the inside by a tire shop.

The tire "guy" at BJ's said he couldn't deal with the plug I installed as it is just outside the tread area and he needs a flat area to place the inside patch over the plugged hole (i.e., they plug and patch as the standard repair). I noted too that the plug I installed seemed to stop the leak but during the flat, my guess, the brief running with little or no air broke the bead at the rim, and that's why I see some air leaking from the tire/rim interface. He seemed to agree that's a possibility and said he'd remove the tire, inspect, reinstall with fresh bead lubricant, ballance and install on car for $9 (maybe it was $9.99), a real reasonable price. But, given he can't put a patch on the inside of the tire I think I'll use this tire for the spare, if it holds air. He did say people have generally good luck with just a plug, which was what was reported on this thread, however, none reported on where plugs in the sidewall, as is mine, just outside the tread area, within 1/8" of the tread, bad luck, but good luck nobody got hurt.

First thing you do when installing a plug is use the supplied reamer to make the hole bigger so the plug will fit.It seems crazy to do more damage and if its a old tire OK but not a newer tire with thousands of miles life left in it.

I have plugged tires for years, never a problem. What irritates me is the whoosy shops that don't seem to want to fix your flat tires. They instead give you a line of garbage as to its illegalities, and won't even fix a fixable tire. I had one they claimed was too close to the edge for a patch, so I told him to just use a plug but they wouldn't, so I told him to pull my car out and I'd plug it myself.

The plug will be fine.

I've also come across places that won't plug a repairable tire. I've even come across places that insist you can't replace a single tire and insist you buy a pair or a set, and that was for tires that were still in very good condition.

Whether an external plug will suffice is dependent upon the technique with which it was installed. It's a relatively simple job to install a plug but if enough rubber cement is not used there could be a bonding or vulcanizing issue. If the plug is not pushed into the treadwall far enough there could be an issue. After the bonding agent has "cured" speeds should not exceed a reasonable velocity. I would keep the speed to a maximum of about 50 MPH or perhaps a bit lower...say 45 MPH. Some locales have a minimum speed of 40 MPH. Plug kits recommend that the plug be used as a TEMPORARY "fix" but that's because of a possible liability that the manufacturer of the plug kits wants to avoid. You, yourself have the burden of deciding how long to use the plugged tire and what speed is "safe" after you plug a tire. Just remember that a brand new tire is more or less structurally safe. Once the tire has become punctured or "insulted" it never again has the very same structural reliability whether is is plugged or internally patched and plugged!

The plug that I prefer has a tulip head. It looks somewhat like an engine valve.. Sealant is put in the hole and a generous amount on the undeside of the head and then a tool is used to force the head into the tire. The plug is pulled outward until the head contacts the inner surface of the tire and then some air pressure is applied to push the head against the tire. The low pressure is held for a period of time until the sealant sets and then full pressure is applied.

For small punctures (up to 8 penny nail size), I have had good luck with the usual rope type plug. However, I have lost rope plugs on larger holes. Fortunately, over the past 7 years, I have had very few punctures and these were small diameter ones.