Ok, first thing to do is find where the air is going. Air up the tire to recommended pressure, put the bike on the centerstand, and spray the entire tire tread, valve stem, and around the bead with Windex. Wherever the leak is, it will show up in a hurry, because the Windex will make bubbles. If it is in the tread, and losing air that slowly, Ride-On alone will probably stop it. If it is around the bead, mark the spot, deflate the tire, and break the bead loose. You don't need to remove the wheel to do that. Look for damage to the tire bead, or a gouge in the rim. If the rim has damage, and it's not really bad, you can probably sand it down smooth and stop the leak. If the tire bead is damaged, it depends on how bad. If it is really bad, you will have to replace the tire. It's very possible that someone who didn't know what they were doing damaged the tire or wheel when they replaced the tire. If there is damage, but it's not that bad, you can get some stuff called bead sealer at most tire shops. You put it on the tire bead, then reinflate the tire. It works most of the time. If it's the valve stem, you might get away with just tightening or replacing the core, but if it is leaking between the stem and wheel, you will need to replace the stem, which usually requires removing the tire. If by some chance, and this isn't likely, it's in the tire sidewall, you will have to replace the tire, as there is no known way to patch a hole in a sidewall. It flexes to much.
I am not one to replace a good tire if it is salvageable. I have a Metzler ME880 on the rear of my bike right now, with a plug in it, and Ride-On in it. Fortunately, it was a small puncture, and right in the middle of a tread groove. The tire only has about 2000 miles on it. It is not dangerous, even if the plug came out (I carry a plug kit and a pump), it would lose air so slowly that I would have a chance to slow down and pull over. So far, it has not lost any air where it is plugged. I squirt some Windex on it every once in a while.
However, whatever you wind up doing about the tire, KEEP THOSE SPLINES LUBED. That is one maintenance item that should never be neglected. Jerry.
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike