What size tire tube for a 26”80mm rim?

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Bigvik51

Bigvik51

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Hi I wanted to put a thickslick on a 80mm rim. The thickslick tire is 26x2 but I wanted to know if I should put a bigger tire tube like a 2.5 since it is going to go on a 80mm rim? Any suggestions would be appreciated.


Thanks!
Vik
 
I have no experience with this arrangement personally, but would be more concerned about the tire than the tube. 80mm is pretty dang wide to mount a 2" tire. Meanwhile, I wouldn't expect the volume inside the tire to increase, only to change its shape--wider & flatter. If that's the case, then a larger tube would be unnecessary.

Anyone care to dispute?
 
Considering that the largest rim size recommended for 2" 559 tires is something like 25mm, and 80mm is more than 3 times that recommended max, I don't think your 2" tire is going to be very happy on a 3.15" (80mm) wide rim.

As you know, 80 mm rims are designed to carry tires wider than 4.2".

The bead walls are going to be forced to a very different angle than what is molded into the tire. If you manage to set the bead and the tire doesn't pop off the rim, it will end up distorted to some sort of half moon shape. Like this:
1683669003364.png


Definitely a unique look!

The CAD model does show that the wide rim results in quite a bit larger enclosed sectional area, something like 55% larger, because the rectangle of the rim starts to dominate the shape, and has much more perimeter length per unit of enclosed area than a circle.
 
I run 26 x 2.125 on 57mm rims and they are good. I tried a 26 x 1.75 on the 57mm rim and while it worked, I wouldn't trust the bead to hold and the rim could get damaged if I hit a bump.
9 Apr 22 - Copy.jpg
80mm would be too wide for 26 x 2.0, but could be made to work. I'd use the same tube the tire would use.
I found a pic of a 26 x 2.125 on an 80 mm rim on Cruiser shop Europe. " 80 mm wide rim - possible but not recommended for daily use"

1683673294331.png
 
twojs.bike said:
I have never attempted anything like this, but based on @axeman88 ’s diagram above, I would suggest a wider tube. Seems like a 26x2 tube would be over inflated by 55%
Click to expand...
Thanks for your confidence and the likes of you other gentlemen. Let me make clear that I'm coming at this from 98% theory, and that my model is very crude. I took the ends of the arcs off the outside of the side walls, for example, with no accounting for wall thickness, and the rim is shown as a simple rectangle.

Still, it's clear that the enclosed volume enclosed must be greater. The tires arc perimeter remains what is built into the tire for both configurations,
- (on my CAD model, tire perimeter is 5.25", and the sidewalls for both images are .219 tall),
while the rim width increases by ( 80 - 25 ) 55mm. That extra perimeter alone. would inevitably increase the sectional area, even if the shape remained a perfect circle.

Is the bead diameter from the axle the same for 80mm as for garden variety 559?
 
Is the bead diameter from the axle the same for 80mm as for garden variety 559?

Diameter is 22 inches for the standard 26 x 1.75 rim. From the axle is radius at 11 inches. I measured my 57 mm and 86 mm rims when I got them, same measurement for tire bead, 22 inches. The facing of the bead to rim is flush with the standard size, once you get far away from that the bead is still there but at a different angle
 
Thank you everyone for your input. I may wait to try this out. I saw a ruff cycle with thickslicks and he said it was an 80mm rim. It looked similar to the pic Wildcat showed earlier on this thread.
 
Wildcat said:
Is the bead diameter from the axle the same for 80mm as for garden variety 559?

Diameter is 22 inches for the standard 26 x 1.75 rim. From the axle is radius at 11 inches. I measured my 57 mm and 86 mm rims when I got them, same measurement for tire bead, 22 inches. The facing of the bead to rim is flush with the standard size, once you get far away from that the bead is still there but at a different angle
Click to expand...
I don’t really know. I’m a noob. I just know I bought an 80mm rim from ruff cycles and it doesn’t fit with the regulator fork they sell on a hard time frame. I was hoping to put a smaller tire and see if that would work. I just may get a different fork
 
On last year's build off bike Girthy Gerty, I used Thickslicks on 26x80 and 26x65mm rims. Used a tube for a 26x2.5" tire on both. It's still holding air. The 80mm rim was for sure a fight to get the tire bead both seated correctly and evenly spaced all around
IMG_20220825_171950676.jpg
 
Good looking bike! I appreciate the comment! I ended up going with a bigger tire. My bike was scraping with the thickslick.
 

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