Am thinking of getting a new uni to replace my 20" beginners one, as I’m sure I’m doing more with that than it was designed for, and would like to do some bigger jumps/drops. It’s also been making horrible creaking noises when I’ve been learning to idle - will hopefully replace the bearings, but not sure if that’s going to fix it. Keen to still have a uni that size, as I find it a lot easier to learn stuff on.
Was thinking of getting a 19" trials one as the most versatile, but then wondering about tyre choice - I have a slick tyre on my current one, which I can pump up hard to make turning easier, handy for stuff like learning to idle. However all the 19" tyres seem to be knobblies. The alternative would be a robust 20", eg http://www.unicycle.uk.com/unicycles/freestyle/20-nimbus-ii-unicycle-blue.html as I see you can now get a big volume trials tyre in that size for when I want that.
So the question is, is there actually any disadvantage to a knobbly 19" trials tyre - am I worrying about nothing, and would it not actually be a problem? Don’t really care much about how well it rolls as I have a 26" muni and a road 29er (when I rebuild the wheel!) for distance riding - if handling for learning tight turns, idling etc. is just as good (if I pump it up hard?) then not an issue. Though I guess I’ve just about sussed idling now, so maybe it’s not important at all. Any advice welcome.
A trial uni will most likely be quite a good choice for a replacement since you can do both freestyle tricks and things like idling and 1ft riding etc and trial/street style riding/practicing and you really don’t have to worry about breaking that uni up! You can also pump up that knobbly fat tyre up to make it more suitable for learning tight curves and other things that require easy rolling. That worked for me very well and later i could just lower the pressure a bit for trials. But it’s mostly just personal preference, if you’re into freestyle and flat then get something that is more suitable for that 
A few years ago I was in the same position - looking for a 20" for practicing skills and thinking about building up a custom wheel with a wide BMX rim because I was afraid of all the extra weight from a big, heavy, knobby trials tire. I wound up just getting a trials uni and it turned out to be the better option for me anyway. The trials tire was fine for practicing new skills like idling and riding backwards. I also wanted to do some hopping around and wouldn’t want a much smaller tire for that. Lastly, the trials will make a good kid’s muni (assuming my sons learn to ride).
Thanks - you pretty much confirmed my thinking. Will be ordering tomorrow, as I broke my beginners one on Friday! Now just to decide whether to buy off the shelf or go custom (very tempted by the latter, the downside being a few extra days before I get to ride it if I also build the wheel myself as planned).
I use the fatty 2.5" tire on my small Muni and its pretty awesome, i found it WAY easier to mount, ride, and turn >< run 20 lbs of pressure in the tire and it hops all of the place effortlessly >< video on my youtube (in signature) of my hopping