They aren't designed for long term use in cars or trucks either... A simple plug is only to get you to a service center to have it either repaired properly (plug/patch combo) or replaced... I am a wholesale distributor and after 20+ years in the tire industry wouldnt trust a plug for anything beyond my riding lawn mower or golf cart. Plugs void all major mfg warranties for a reason. Yes, some have had no problems with plugs but at the very least it should be repaired with a patch and idealy with a plug patch combo.
Replacing it isnt too bad of an idea either considering the demands placed on a tire and the results of one that fails.

YMMV

 

I have seen the new plugs installed and they will not give you trouble,wear out your tire after having plugged at a tire store.

 

I have plugged three rear tires one on my Roadking,Nightrain and the most impressive was on my Hayabusa. The tire had 100 miles on it and put a Autozone plug in it in the dark. No problems, ran it till the cords started to show. If a tire will stay together with a 170 horsepowerand 195+mphit should stay together with a HD.

 

There will always be folks whove never had a problem with a plug. Thats good, but if I can lessen the odds of a quick deflation of my rear tire at speed or in heavy traffic, Im going to do it.If you run spokes, get a new tube; if not, I stongly recommend youreplace the tire. I had a rear blow out on my Norton at 70 mph over 30 years ago and I never want that to happen again.

 

air it up and smoke it till it pops then buy a new 1

 

This is an age old question that always get a variety of answers. Personal experience ... I've had three tires with plugs, one had three. I won't plug a front tire but I wouldn't think twice about the rear tire. Also, I won't let anyone else plug my tires ... it's my A$$ on the line and I want to know it's done right.