Tire repair plugs on my daily driver

[funola]

On my daily driver, a 92 VW idi diesel, I've been driving around for a year on a 2 diagonal (F&R) tires with a very slow leak. Last summer I pulled the wheels, submerged in water but saw no bubbles. So I put them back on and just keep putting air in them every 4 to 6 days where it would lose about 5 to 10 psi. These tires have about 30 % thread life left and I did not feel like getting them fixed @ $12 ea at a tire shop or buy new tires just yet. A few days ago I I pulled the wheels again to find the leak and found a finishing nail in each tire hidden under the threads. I sprayed soapy water on it and it showed a tiny bubble approx every 5 seconds, which explains why I did not see any bubbles in the submerged test. (Pic shows nail pulled out a little with dikes).

I learned long ago if you have a nail in your tire, don't pull it out unless you are prepared to fix it immediately otherwise you are guaranteed a flat. Apparently I drove around for a year with 2 nails in the tires with no collateral damage!

So I pulled the nails and put a plug in each, no bubbles per soapy water, inflated and installed the wheels and so far they are holding pressure. The tire plug package instructions says this is a temporary fix and to get a proper patch installed. I don't understand why that is since the patch plug (no leaks) has to be better than the nail plug (very slow leak) that was there.

Anyone with experience driving around with a tire plug?

Some notes:
1. I was not strong enough to push the rasp cleaning tool nor the tire plug tool into the tire. I had to hammer them in with a rubber mallet.

2. Dikes (wire cutter) did not trim the plugs which were tough and springy. I had to use scissors, which made it easier but still tough to cut.

3. If the tire is fully inflated (I keep mine at around 40 psi), if you work quickly after pulling the nail, the tire will not be totally flat and you should have enough air in it to drive to a gas station.

4. I am keeping all tools and parts needed in the car to do a tire plug, which can be done with wheel mounted.