Hey I’m not finding much on this style of uni. I think the Nimbus Purple Monster and Sun also makes one with a 4-1/4 to 4.5" wide tire. What is up with this, kinda just for fun or something different? Sounds like it would come in handy if you needed traction.
It seems like it would be just massive and I have to admit I’m a little intrigued. 
IF anyone has experience with this thing, let me know your honest opinion.
Thanks
I had a Nimbus Monster unicycle for about 5 years and just sold it a few days ago. The tyre is 4 1/4" wide and its a Duro Boomerang (in the US I think these unicycles are called Nimbus Boomerang, after the tyre). It looks like it would be great for hopping and have amazing traction, but in fact you have to pump it up quite hard otherwise it is awful to ride. The wheel is quite heavy, so you have to put a bit of muscle into making sharp turns. The upside of the heavy wheel is that it goes in straight lines very readily and stays upright once you are moving - my seat drag ability benefitted from this effect! Overall, my Monster hasn’t seen a lot of use but it is a fun and very different unicycle.
Well im glad someone chimed in! They look crazy but i think i’ll only consider one after I have the other 2 or 3 I want 
It looks like it’d be exactly like you described .
Are these things easy to learn on??
Sun XL or Nimbus/Unicycle.com Purple Monster??
They would be fine to learn on, you would just want to pump the tire up to lower the rolling resistance. It’s a little heavy, so it will feel different than a normal old 20 or 24" starter, and the hub is wider, but there’s no reason you couldn’t learn on one. Diameter is about right to start on.
They suck to ride. Just a show or fun piece. I found them great fun to try tricks on if there is one at a convention, in the same way that tricks on a 12" are fun. I don’t think you ever need a tire >3" wide for traction reasons, unless you really really want to ride in loose sand.
(I realize this is old, but decided give my opinion anyway)
I would not recommend it. The one thing you have to learn when you are new to unicycling is your balance forward and backwards, which will be harder to learn with a wheel with that much momentum. IF you managed to learn on this (it’s definetely not impossible, just harder I think) and went to a smaller wheel, you would likely have developed some bad habits, for instance sitting down is really important on most unicycles so it doesn’t twist side to side with your pedalstrokes, but with a heavy wheel that would not matter.