Which 29er tube is the best for a 36" rim?
I have found that Schwalbe manufacture both 60-622 and 40-635. Is the tube which is 20 mm wider more suitable than the one that is 13 mm longer?
My chickenbrain can’t figure it out.
What brand and size do you use?
That’s a good question. I have Kenda tubes that are marked: 29x2.3-700x47/58. The box says “inline” brand, but the tube says kenda. They seem to work well, but that doesn’t begin to answer your question.
I use whatever is cheapest. I bought 10 tubes for $20 online somewhere. The key is to stretch out the tube really well before you attempt to mount it. I inflate it way past 36" and leave it to stretch out overnight. I then take great care to mount it so there are no pinches in the tire. I can go more than a year riding a lot without replacing the tube once it is set right. I get flats on my 29er muni (cactus and thorns) but almost never on my 36er. Good luck!
Don’t you think size and quality will influence on how long they will last? If I can avoide the wrestling it takes to switch tube by buying another brand or size I would gladly do so.
Size certainly matters. As a general rule the more rubber you have in the tube the less flats you will have, and the less often you will have to top off the air. That being said the 36" tubes are crazy heavy, and I don’t mind filling my tire a little more often.
As for quality, I worked at a bike shop for 10 years and saw a lot of different tubes that were pushed as being “high quality.” In truth there have been bad tubes, but generally it is an occasional bad tube not a brand or model. For standard butyl rubber tubes I haven’t seen any that I would say are categorically “higher quality.”
Avoid Latex tubes, they bleed air like crazy. Avoid PU tubes, they don’t stretch that much and won’t fill the space.
I’ve used Continental “MTB 28” tubes in my 36" without any fitting or leakage problems so far
I’m using a Schwalbe 29er tube, the widest I could find at the time (I think it’s something like 700x50c). I’ve never actually had a puncture on my coker - the only time I’ve needed to change the tube is when I pinched one removing the tyre to put it on a new wheel.
There are some 29er tubes around that are advertised as 1.75-2.5" wide, which would be even better, but I’ve not had problems with mine. Any 29er tube is going to be way lighter than a proper coker tube, so you may as well go for the widest you can get, seeing as it’s going to get overstretched anyway.
Like somebody else mentioned, stretch the tube well by leaving it pumped up quite fat for a day or so before fitting, and put a little bit of air in it when you’re fitting it to help stop it getting pinched. When I’ve done it (only twice in the whole time I’ve had my 36er - once when I got the new wheel and the second time when a spoke nipple broke) I haven’t found it to be as difficult as I was expecting.
Rob
I have a Schwalbe 29 innertube the same as Rob’s 36. I haven’t had a single puncture the whole distance from Land’s end to John o Groats. Pretty much just do as everyone has said, Overinflate the tube, leave it over night, then care not to pinch it. Also, I will add, from my (well, my dad’s) own experience, when you start the process of over inflating the tube, make sure to pump it, stretch it out for a minute or so, continue pumping, stretch, continue pumping etc. This is because the first time, Dad went straight into pumping, and it blew up on him. It was quite hillarious. Except for the whiplash.
Chickenbrain indeed. A 635 mm diameter tube should be 40 mm longer than a 622 mm tube. Not 13 mm.
I use the same ones.
Wondering if a 32" tube would work for a 36er. Since many have used 29er tubes to save weight, I’m thinking the 32" might be an easier fit and still be lighter than a 36er tube.
How do you keep the tube from getting caught under the tire bead? I’ve tried reinstalling several times but I can’t get the tube totally inside the bead. At least part of the tube squishes out and can’t get it back inside tire.
If you add more air to the tube it should stay out of the way of the tire bead. I have not had that problem.
I like the Schwalbe because you can get it with a fully-threaded valve stem with the little round nut. This is helpful because it keeps the tube in exactly the correct place, and the valve stem is never at risk of “disappearing” into the wheel when attaching an air hose. In my experience, the 29" tube works well for both the 36" and 32" wheels. 
Is that a presta valve then, or just a schrader that shares that feature with one?
My tubes are all Shaders.
Speaking of the tube itself, I’ve been wondering a bit about getting a spare as I start doing longer distances on the 36er.
What I haven’t figured out is how many miles of walk-out compare to carrying around the necessary tools and supplies and hand-pumping a 36er from nothing with a portable pump.
And on the tube itself, how often is replacing the tube going to be a noticeable win over field patching with a tiny kit? Anything near the valve, and presumably any large tear, but that would probably call the tire into question, too.
I’ve hear rumors like needing three extra large tire levers; realistically what would one need to carry?
Stopped next to a guy on the roughly paved trail changing a road bike tire, his comment was he’d never had a flat on his mountain bike, but they were a common frustration on a road bike. Presumably we get the large tire benefit and then some.
I’m using Michelin Butyl 700mm 35-47mm : 175g !
Successfully installed this tube on my Geared 36er (following bouin-bouin’s choice), it is 168gm, who can say less? 
It fitted well the King George tire.
My previous tube was a 220 gm schlwalbe 29er tube, and since the Schlumpf hub makes the wheel heavy, I appreciate this 50gm lighter tube, I’m pretty sure I felt some difference during my last ride. (you know, the one I crashed at 17 mph because of a accidental downshift 
)
I don’t have a 29" tube in my 36. I have a 36" Foss tube. Makes an amazing difference to weight, comfort and response. I also have a Foss tube in my 29. Highly recommended. (I haven’t checked, but I’m assuming they’re still available.)