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Nemophilist
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Discussion Starter #1 (Edited)
Fat Tire Profiles - For The Archives

Hey;

If anyone does a search for this info, this thread should come up.

This is a fairly accurate profile of a 45NORTH Husker Du tire mounted to an 80mm rim.
Helpful for frame building and other fitment needs.

 
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Thanks for that Trailmaker!
One day I'll have to measure the other fat tires I have and add them to this thread. And maybe also get said tire specs Shiggy's mtbtires site too...

Edit:
It'd be good to also have the other wheel specs too, like outside diameter (with tire) & radius to widest point of tire to help with the chainstay dimpling and seat stay bending...
 

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Nemophilist
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Discussion Starter #3
Well....

Someone is on the ball! I have some numbers right here. Think I would have remembered to include them? These numbers were taken from a Husker Du mounted on a Graceful Fat Sheba. I imagine they would be the same for the one I have mounted on a Rolling Daryl.

Mounted Diameter - 28.66"/727.96mm
Mounted Circumference - 90"/2286mm
Mounted Tire Height - 3.125"/79.37mm (from rim to top)
Mounted Max Width (@ Center) - 1.5625/39.68mm

If others want to post information on other combinations, I'll change the title of the thread. Thanks Whit!
 

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Surly Nate dimensions

How did you make these measurements? Mine are not going to be as precise as yours, especially if we don't measure things with the same method but here's what I got for the Surly Nate tire anyhow. I'll measure up my Endomorph and Larry a bit later. I just used my digital calipers and a long metric yardstick to estimate these. Also, I hear the tire sizes within a given type (Nate, BFL, Endo) vary a bit (or a lot) with the Surly tires. I've noticed that each of my fatbike tires has at least a little warble in it (not the rim, but the tire itself).

Surly Nate 26" x 4.0":
Tread width = 96mm
Casing width = 97mm
Diameter = 734mm
Rim edge to top of tire tread = 80mm
axle to widest point of tire sidewall = between 315 - 345mm.

I know this is obvious for most but I'll write it anyhow since I didn't really 'get it' until i did it once: That last measurement is what helps me figure out where to place the bend in the chainstays and how much to dimple. The overall wheel diameter helps me with BB height and drop and figure out how long the chainstays need to be so that the wheel clears the seat tube since i don't bend the ST yet.
 

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Nemophilist
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Discussion Starter #5
Psssshh...

I don't have oversize calipers (wish I did, but $$$), so I used the old fashioned method. I trimmed a piece of thin cardboard to fit the side profile of the tire, measured some key points, and then scanned it in and did sizing/ dimensioning it on the computer. It is a fairly accurate model. I like your axle-to-Fatest spec. I'll get one tomorrow.
 

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no dabs
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How did you make these measurements? Mine are not going to be as precise as yours, especially if we don't measure things with the same method but here's what I got for the Surly Nate tire anyhow. I'll measure up my Endomorph and Larry a bit later. I just used my digital calipers and a long metric yardstick to estimate these. Also, I hear the tire sizes within a given type (Nate, BFL, Endo) vary a bit (or a lot) with the Surly tires. I've noticed that each of my fatbike tires has at least a little warble in it (not the rim, but the tire itself).

Surly Nate 26" x 4.0":
Tread width = 96mm
Casing width = 97mm
Diameter = 734mm
Rim edge to top of tire tread = 80mm
axle to widest point of tire sidewall = between 315 - 345mm.

I know this is obvious for most but I'll write it anyhow since I didn't really 'get it' until i did it once: That last measurement is what helps me figure out where to place the bend in the chainstays and how much to dimple. The overall wheel diameter helps me with BB height and drop and figure out how long the chainstays need to be so that the wheel clears the seat tube since i don't bend the ST yet.
Maybe I missed it, but it doesn't look like you've mentioned which rim this is on. I'm guessing it is narrower than a hundie, since that is considerably less width than I measured....?
 

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Nemophilist
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Discussion Starter #8
Hey;

For some reason, the edit function is not available to me, so I will do it this way. I need to revise the numbers posted above. Corrected numbers are in bold/underline.

Mounted Diameter - 28.34"/720mm
Mounted Circumference - 88.98"/2260mm
Mounted Tire Height - 3.125"/79.37mm (from rim to top)
Mounted Max Width (@ Center) - 1.5625/39.68mm

Incidentally, the numbers for the Nate are virtually identical, so I assume they must be made on the same casing.
 

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Harrumph
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Since it's sitting right here in front of meand I haven't seen the info elsewhere here's the #'s for a HD on a 100mm Clownshoe. A fairly used first run steel bead HD with a Q'Tubes superlight 26x2.7 tube @ 10ish psi.

Diameter: 735mm
Circumference: 2300mm
Max Width: 107mm @325mm from axle
Max Knob: 93 @ 355mm from axle

Not measured terribly accurately, but keep in mind things like the psi, temperature, and age (they kinda stretch out) will cause measurable changes. And that's if you are measuring the exact same rim/tube/tire combo. Even for a specific tire the various casing options/tpi's and bead material further cause differences. The tube used (or not used) can change the profile too.

Oh yea, and THEN there's the production variances for these tires!

So round up generously for clearances.
 

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Nemophilist
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Discussion Starter #12
No Kidding;

I mounted my 120TPI HDs, pumped them up to 40psi, and let them sit for a month or so while I was building the Humvee. I had one of them that simply REFUSED to pop and seat on the bead of the tire. I tried everything known to man and it simply would not pop out, and it was always in the same spot. I finally decided it was just a "peculiarity" of this tire and let it go. I put it on the back because I figured that looking down and seeing the extreme wobble would drive me nuts.

I noted from time to time that it was still goofy after I began using the bike. At some point when I was servicing something and spinning the rear wheel, I noted that it was spinning true. This was a long time and quite a few miles after I started riding it. I also noted that I could see a faint line in the rubber where it had been seated on the rim lip previously.

Given that soap - both dry and wet - and heat and WD40 and countless re-mountings and everything else at 40psi did not do the job, I am forced to conclude that nothing but time and travail was going to bring that bead out where it belonged.

Chinese QC is still a moving target.
 

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Surly Lou on a Clown Shoe

- 350mm axle to widest point of tire which is the side knob. This was measured as seen in photo - outside of a 190 hub at the center of the axle with a steel ruler.
- Widest point of casing was hard to pinpoint but was between 325 - 330mm from axle.
- Widest point of tire is at knobs and is about 113mm.
- Widest point of tire at casing is just a hair less than the knobs, around 112mm.
- Diameter to the best of my abilities of measuring this is about 755mm.

You'll see that my measurements are similar to Surly's (seen on that website Walt linked above) but that the tire width at both casing and tread are way smaller than stated (they claim 121 and 119).
I'm just happy that the actual size is *smaller* than the stated so I have plenty of tire clearance built into the frame instead of the opposite!

Lou-width.jpg

Lou_size.jpg
 
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