Fattest tube is 26 x 2.5, might be stretchy enough to work with a 3" tire, but this tube is too pricey for me, so I’ll step aside and let Feisty buy the first one 
Hey Ben,
Why don’t you just go tubeless?
Both my 36er and MUni have been tubless for 18 months, saved over 400 grams of weight in the MUni and a bit more on the 36er.
I have been running tubeless on my MTB for over 4 years, ride it most weeks and had one puncher in that time! that was a piece of steel that went through both sides of the tyre and left 3/4 inch gashes so I guess that is acceptable 
I use stans fluid and fibre tape to seal the spoke holes, tubes are dead! 
Cheers.
He did…
Basically the same concept at the FOSS tube, which is also among the lightest tubes on the market.
Hey Pete, I run my 36er tubeless, but my 29er is tubed until I get a Knard. Tubeless is pretty good, no complaints, my 36er hasn’t needed any air added for a month.
The Eclipse tubes are lighter than Foss, but more importantly I think they are also more durable. I broke a Foss valve and I think there have been more than a few folks who had leaks/pinches.
Tubeless is good except for one thing: getting a blowout a long way from home. lightweight tube is a good backup for tubeless. I carry a Foss 36er tube when I go cokering.
Maybe I’ve just been lucky, but I’ve put in thousands of miles using my FOSS tube, and have had no issues yet. It’s been an outstanding tube. And it’s funny how we talk about shaving grams or an ounce or two from the wheel, and then add a Schlumpf hub! 
I don’t think they will stretch into a 36" tyre 
I followed these when they were being developed on the MTBR forum, there were lots of issues with micro leaks at the joins initially and were really meant to be used with a sealant inside. I was riding 90g normal conto flyweight tubes anyway which were cheap enough so didn’t see the point.
I think I am running 140g or 160g 29er tubes in my 36" anyway so light enough.
I also remember seeing those on MTBR (which dates them, given how long it is since I’ve been on there!) Ironically I already have Eclipse inside my tyres on one set of wheels - back in the day they made tubeless rim strips.
yeah takes me back, I sat on my Bike the other day and tried to ride accros the kitchen and I sucked, a year of Uni riding has killed 30 years of bike riding
You should be proud of that!
ROFL! 
Was it as hard as the first time you rode a uni?
I maybe embellishing a little but it felt so wrong and twitchy putting all that weight on the handle bars.
My bike is awesome though and I would never get shot of it, the Mrs rides it now.
I have sold my mtb and my trials bike to fund the unicycles