I talked to UDC today and they felt that 1.95 was as wide as you could go on this frame without danger of rubbing.
I have found that you can get different answers from UDC depending on who you get on the phone.
So what is the consensus here? 1.95" or can I go wider say up to 2.1 or even 2.2?
From what I have been hearing on these forums Nimbus frames seem to be really variable. Some have more clearance and some have less. I don’t know if it is from different production runs or if there is just that much variability in manufacturing. If it were a production run thing I wish that they would then tell you what “year” a frame was from.
I would be disappointed if it could only fit a 1.95
Maybe you could ask them to switch the frame out for one meant for a 19" wheel. (they are slightly taller)
If it is an old frame with the pressed bearing holders you can add shims, It is not that easy with the new machined holders though.
I would be very surprised if 2.1 or 2.2 rubs in a Nimbus II frame. My favourite freestyle tire at the moment is a Maxxis Miracle 20" x 2.1. The Onza Sticky fingers 20 x 2.4 is sold to fit standard 20" rim and frame setups so you can’t go wrong with 2.1!
They would have to use such fine tolerances to get the crown in so close as to rub a 2.1 that I don’t believe anyone who says it! I’ll believe it if I see it. Maybe the person on the phone was erring on the side of caution and wanted to sound like they knew what they were talking about even though they weren’t sure?
Hopefully I can get some consensus because shipping is expensive, and slow from Atlanta to west coast. Would rather get it right the first time. If 1.95 is the widest than I will probably rethink my decision.
Bumpity bumptiy… any info on this would really help me.
The clearence on the frame should give 6mm clearence on a 2.1 tyre when using the Nimbus freestyle rim. If you use a wider rim then the clearence will be less.
Roger
THANK YOU! Information I can work with.
Now I just need to find out if I can upgrade to 2.1" tire or if I have to buy two tires.
If you’re new to all this, please note that tire widths are approximate. The numbers printed on the side are “about” how wide the tire will be, when mounted on an unknown rim size. In other words, it’s hard to know exactly how wide an inflated tire will be without actually inflating it on the specific width of rim being asked about, and measuring how wide it is.
Frames are easier. Long as you know you’re all talking about the same frame (which is sometimes not that easy), someone can measure and those are the numbers. 
Nimbus 20" rim + 20x1.95 Kickzumbut and 20" Primo 20x2.1 Wall as design references when checking.
I will add more confusion… the frames were designed with those clearances. It was realised that different batches of frames have varied in their clearance. The tollerance have been something like -4 to +25mm! The reason behind this is to get the tyres also to fit the 20"x 2.5 Trials tyres.
Basically, measure your frame to be sure that wheels/tyre combinations fit.
Roger
Thanks Guys.
So Roger what do I do when ordering? Ask for a wide one??? I’m joking unless that is what I should do.
I think i’m going to start with the Kikzumbut, and I’l go wider when the need arises and I can source it locally.
Now since John’s other post I have to rethink crank lenght… I’m really looking to learn tight turns on this John, you really think 114 would be better for that over the 125 I was going to go with for clearance?
My 24" have 150’s
Width is not the problem, it is height that will be your constraint. If you are just fitting a 2.1 on a standard rim you wont have a problem.
Roger
Sweet! thanks Roger. You have been really helpful and it is much appreciated.
Do you have any opinion on the Animal GLH tire?
It is a tyre that has not made it to the UK so I have no experice with it at all, sorry. The specifications and the look of it is impressive and I would guess is it would make a good freestyle tyre.
I will certainly see if I can get hold of one to test though.
Regards
Roger
Roger, just so you know, I’m not trying to put together a freestyle uni. No foot on frame tricks. Trey this, flip that, Think of it as a go anywhere, small drops, tight turning, hops no higher than up stairs versatile 20" uni to play on in street/playground environment. But no grinding or other street tricks. I’m a roller, not a hop in place rider. That’s why the emphasis on a little wider tire. Not interested in a true trials/street uni. Want to stay with 20" rim. And no I don’t plan to go wider than 32mm rim.
You have been so helpful to me, can’t thank you enough.
OK, I know what you are looking for.
Weight is also an issue which is part of the reason why you are avoiding the 19" tyres and rims. Loosing weight does make a more agile unicyle.
Going wider on the rim makes the tyre volume bigger. It also makes for stability on landing… but adds weight. Always a compromise. You will know the best format for yourself and your style of riding.
Roger