I built homes for a living for about 16 years. Nails and screws in tires is just part of the job. I would guess I have installed a hundred plugs. I have never had a problem with a plug, however, it can be difficult to get the plug through the steel belt, and a poorly installed plug could fail. I consider plugs as permanent. I believe the mention of "temporary" is a CYA statement for those that have trouble installing the plug properly. A simple patch without a plug, is not a proper repair as water and air can get to the steel belt and cause it to deteriorate. A simple patch over a plug is fine, but if the plug is holding air, I would not bother.

I have a steel plug in my pickup tire that has been there for at least 5 years. Sometimes those nails go straight in and don't cause a leak.

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'97 E 300 D