M35A3 wheel beadlocks

gringeltaube

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do yourself a huge favor and make sure you have 10" wide bead locks.
Not so sure, I think 10" won't fit, IMHO........
The A3 wheel measures exactly 11 inches from (rim) flange to flange, and the bead thickness of a typical 395 is more or less 1-5/16". With the tire mounted - and beads well seated - that leaves 8-3/8" free space in between them. So your beadlock should be anything between 8-1/2" (for PVC) and about 8-3/4" (say maximum 9") if it was rubber.
 

HDN

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Not so sure, I think 10" won't fit, IMHO........
The A3 wheel measures exactly 11 inches from (rim) flange to flange, and the bead thickness of a typical 395 is more or less 1-5/16". With the tire mounted - and beads well seated - that leaves 8-3/8" free space in between them. So your beadlock should be anything between 8-1/2" (for PVC) and about 8-3/4" (say maximum 9") if it was rubber.
Now I understand what @tobyS meant when he mentioned the bead thickness. I'll have to compare them. If my stock bead locks are too wide, I might eschew them and just make sure I never air down the tires! I don't really feel like hunting for narrower bead locks.

Now if I got the Continental MPT81 365s instead, is there even a guarantee there that the bead wouldn't be a different thickness from the old Michelin 14.5s I took off?
 

Sgt Jiggins

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Not so sure, I think 10" won't fit, IMHO........
That may be. I have yet to yank apart a properly aired tire to check. That's a LOT of work. I do know for 100% certain that at 7.5" and 8", it was nowhere close. A 9" might work. In all honesty, I don't know exactly. What I do know is what a pain it is to deal with if you get to that point without the correct size beadlocks.

You'd have to have a fairly decent surge tank or explosively inflate them. There was no way my ancient 250gal belt-driven compressor had enough ass to get those beads to seat without the proper beadlocks. And that's saying something, that thing isn't a wimp.
 

Sgt Jiggins

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Now I understand what @tobyS meant when he mentioned the bead thickness. I'll have to compare them. If my stock bead locks are too wide, I might eschew them and just make sure I never air down the tires! I don't really feel like hunting for narrower bead locks.
I think what @tobyS was getting at with that:

You have diameter (21" ID it looks like). Then you have width (10" on ones I'm looking at as I type this). And then thickness. I have 2 that are the same thickness and then one oddball. The difference, as @tobyS can attest, is ~10#.
 

tobyS

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The hunt for a narrower one is easy.....they are on all the 5 ton combat singles. They measure 9".

The question is, how much compression is needed. With a 1 5/16 bead x2 = 2 5/8". Then 11" - 2 5/8" = 8 3/8". Thus using a 10" actual width beadlock is compressed 1 5/8". Man....that sounds like a lot...even difficult to get bolts started.
 

gringeltaube

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The question is, how much compression is needed.
OK, to respond that let's assume that Hutchinson knows well what they are doing....:giggle: If so, then each of the beads of a 395 XZL tire - mounted on a 10" wide rim - will have to give/compress/deform:
A) about 0.2", if we installed their rubber-outlined steel band beadlock (p/n 12414420), which is 7.88" wide (and almost solid, incompressible);
B) estimated 0.15", if the tire had inserted their 1-pc rubber runflat (VF0018 ), measuring 7.92" width OA and most likely more flexible, compressible than A).

So, if the amount of tire bead "compression" should remain more or less the same when we put a 395 tire on an 11"-wide rim, then we need something in between 8-7/8" and 9.0", depending on material resiliency.

Easiest for me would be cutting and widening the original steel-band-type beadlock by exactly one inch.

....then dropping back to the beadlock used in 10" wheels (measures 9")
9"....? Are you sure about that? Too bad I don't have any here, to confirm. But I know that the beads of the 14.00s and 395s are similar in size. And I think that such a bead really can't compress much more than say 0.25". Meaning that a 9"-wide (rubber)beadlock would have to "absorb" the remaining difference of (9.0-0.5-7.4 = 1.1) over 1 inch! Seems a bit excessive to me....
 

HDN

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I just took a few measurements:

Michelin XL takeoff 14.5R20
Tire bead thickness - 1.25"
Distance between inner bead edges - 7.5"

Michelin XZL used 395/85R20
Tire bead thickness - 1.25"
Distance between inner bead edges - 6.75"

So bead thickness is the same, but the distance between inner bead edges, as previously noted, is smaller for the 395. So I should be able to use the 10" rubber bead lock inserts in these tires and they'll fit properly on the M35A3 rim as a result. But it'll just be a tight fit between the bead lock insert and the beads.

EDIT: Found the answer regarding stock M35A3 bead locks. It was under my nose this entire time in this awesome thread I've been using as a resource: https://www.steelsoldiers.com/threads/m35a3-tire-changing-to-395-85-20-part-1.72366/post-965730
 
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tobyS

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I just took a few measurements:

Michelin XL takeoff 14.5R20
Tire bead thickness - 1.25"
Distance between inner bead edges - 7.5"

Michelin XZL used 395/85R20
Tire bead thickness - 1.25"
Distance between inner bead edges - 6.75"

So bead thickness is the same, but the distance between inner bead edges, as previously noted, is smaller for the 395. So I should be able to use the 10" rubber bead lock inserts in these tires and they'll fit properly on the M35A3 rim as a result. But it'll just be a tight fit between the bead lock insert and the beads.

EDIT: Found the answer regarding stock M35A3 bead locks. It was under my nose this entire time in this awesome thread I've been using as a resource: https://www.steelsoldiers.com/threads/m35a3-tire-changing-to-395-85-20-part-1.72366/post-965730
I read that and note that it gets tight with 1" left and that 350 ft lbs will not seal but 450 will. To me, that is indication that with the tires aired up, we may be close to the limits of our bolts. Do we need that much compression that just getting them together is so tight? I'm sure Henderson knows what is best, but I'm going to hang onto my 9" wide beadlocks for now.
 

HDN

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I read that and note that it gets tight with 1" left and that 350 ft lbs will not seal but 450 will. To me, that is indication that with the tires aired up, we may be close to the limits of our bolts. Do we need that much compression that just getting them together is so tight? I'm sure Henderson knows what is best, but I'm going to hang onto my 9" wide beadlocks for now.
The TM calls for that much torque on the bead lock nuts, so it's normal.

1626782893838.png
 

tobyS

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I see I was wrong....a 7/8 grade 8 is rated to about 500, fine thread. So the bolt is not the weak link.

I've been working on the sand trail tire rims which have 24. It makes the A3 rim appear less robust....but that's just my opinion. Since I don't air down, I want enough to hold it out when flat, but not so much to run that way. Even 9" gives 1/2-5/8" compression.
 

HDN

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I see I was wrong....a 7/8 grade 8 is rated to about 500, fine thread. So the bolt is not the weak link.

I've been working on the sand trail tire rims which have 24. It makes the A3 rim appear less robust....but that's just my opinion. Since I don't air down, I want enough to hold it out when flat, but not so much to run that way. Even 9" gives 1/2-5/8" compression.
It seems compared to the A2 rims, the A3 rims are less robust. Each rim has a load capacity of 4000 lbs, which is much less than the tires. One probably shouldn't load 5 tons of stuff in the back of an M35A3 with these rims like the A2. That said, the rims on the front end are already supporting 3000 lbs each for an empty truck, so they're already pushing that.

Then again, the A2 runs duals typically, so maybe the individual rims have a lower cap than 4000 lbs but the duals help? I'm not sure.

Sure there's probably a safety factor built in, but do we really want to test that? :)
 

HDN

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I think I see why there might be confusion over the torque values for the bead lock (or clamp ring, as the tire TM calls it). The M939A1 clamp rings only require at most 250 ft-lbs of torque per lock nut, which is almost half that required for the M35A3 rim clamp ring o_O
 

HDN

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Back to bead lock inserts...

I think I figured out why I had such a hard time getting the rim out of the tire:

20210812_133525.jpg

The bead lock insert appears to be warped. Maybe the tire sitting flat could've done this? I think I can reuse it since the beads on the 395 are closer together than on the 365. Thoughts?
 

HDN

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The bead lock insert appears to be warped. Maybe the tire sitting flat could've done this? I think I can reuse it since the beads on the 395 are closer together than on the 365. Thoughts?
Just an update since I got some notes about this thread this morning - I did re-use the bead lock insert. Everything went back together with a 395 tire without issue. I took the truck on the road once since and didn't notice any problems related to the warped insert. If anything, it actually drove better with two newer 395s on the front axle :)
 

tobyS

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Im glad they work for you. I think the Michelins start off rounder and more in balance but don't have any GY to compare.

My point about the bead locks is theoretical ....why so much compressive force when some people run quite successful without them. Sure, no airing down for sand without them.

It's just a guess, but the likelihood of an A3 sitting for extended periods with 6 flats is quite high, (CTIS) so they needed lots of side pressure to air up from the small compressor. That assumes there is less leakage when flat if held really tight.

HDN, the stuck and rusted may be from the side compression that tightens it on the rim as its drawn in.

A committee built the A3.
 
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