Have used the sticky worm type plugs--with the addition of rubber cement--for over 25 years on all my cars and trucks, at least 30-40 repairs, and have NEVER had one fail. I've used them several times on mc tires, and again, have NEVER had one fail. The Avons on my '04 FJR are approaching 13,000 miles and the rear tire has had a sticky worm plug for the past 4000 miles--no problem at all. In fact, I have trouble even finding where the plug is. I used a mushroom type Stop'nGo type plug one time--lasted 50 miles until I got home, was flat the next morning. Steel belted tires can cut the mushroom head off when tire flexes, depending on where the plug is in relation to the nearest steel belt. Doesn't seem to affect the sticky worms, which are made of much tougher material. I'll never use the mushroom plug again.
Lee in the Mountains of Northern California