Originally Posted by WhyFi

Some have a metal plug, some don't. The ones that I used didn't have a plug and they wouldn't stay in, not with the bike free hanging at home, at least. If you were to plug it in the field and ride on it immediately, it probably wouldn't push out, or at least not as readily (it would take about 30+ min to push out for me). Tire thickness might have an effect, too - my experience was with some Hutch Fusion 5 Performance 11-Storm (they need a shorter name); they're not race-day tires, but there's not a ton of meat on them, either, so maybe not as much in-the-hole thickness for stiction.