I've been plugging tires since I was a teenager. They used to sell this type of plug everywhere, but they have all gone to the wimpy, very rope-like, plugs that don't hold air well. This type is just like the ones I used to use a long time ago. It's more like a dense gummy rubber instead of a coarse rope coated in goo. I've plugged two tires on my lawnmower so far because the old guy who owned my land before left weird stuff all over the yard for my mower to find. and hit. No leaks, even without using the glue stuff. I wouldn't hesitate to plug automotive tires with them either.