Tires blowing off Stan's Alpha 340 rims

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SpoonMan
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by SpoonMan

I just recently got a set of Tune Skyline RRs. They're Stan's 340 rims. I was told at purchase that there were only certain tyres suitable for use with the 340s - and that they would not supply GP4000s, or Vittoria pretty much anything to go on them. I ended up with some Schwalbe Ultremos, and am reasonably happy. My LBS mentioned it as though it was reasonably well known, so I didn't think much of it.
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artray
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by artray

The rims look really thin in that photo. The next time I take my tyre off I will have a look and see if its one or two layers of tape .I have been using zx or r1 tyres and no issues what so ever . When mounting a tyre I always inflate a bit 60psi then deflate make sure its all straight then pump up to 110/120psi .

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WMW
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by WMW

SpoonMan wrote:I just recently got a set of Tune Skyline RRs. They're Stan's 340 rims. I was told at purchase that there were only certain tyres suitable for use with the 340s - and that they would not supply GP4000s, or Vittoria pretty much anything to go on them. I ended up with some Schwalbe Ultremos, and am reasonably happy. My LBS mentioned it as though it was reasonably well known, so I didn't think much of it.


Well... that is news to me. Can you get some clarification on what tires they *do* recommend.

Stan didn't forbid using GP4000... although he did mention that some German riders experienced GP4000 blowing off until they put on the two layers of 21mm tape. I caution against assuming too much just because some GP4000s have come off. It's a very popular tire, so it may not mean they are more prone. And I'm pretty sure all the top Conti tires have the same bead, so another Conti model would not be any better.

In fact I wonder if any kevlar beaded tires are safe... aren't the beads very similar? The Contis go on tight, but get loose after awhile. The 340 rim stretches the bead more than most. I just took one off the 340 rim and mounted it on an XR200, and it was very easy... too easy to put on. I pumped it up and the bead wasn't seating evenly... making the tire lumpy. A new tire fits tight on the XR200. It doesn't seem right for a bead to permanently elongate that much.
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SpoonMan
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by SpoonMan

Direct from the email from my LBS:

We also have just received a bulletin from Tune & Stans – apparently their Alpha 340 rims (the rims used for the Skyline RR wheels) have had a compatibility issue with certain tyres. It looks like some tyres are a particularly loose fit on the rim, which can lead to the tyre rolling off under extreme circumstances. Which tyres are you planning on running?

I’ve have been using Schwalbe Ultremo tyres on my own Skylines, and have fitted other Schwalbe tyres to previous sets of Skylines we have sold – there appears to be no issues with this combination. If you’re planning to run a different set of tyres, it would be best for you to bring your tyres & tubes in for us to fit & evaluate their compatibility. Stans are saying that Conti GP4000s should not be used with the Alpha rims (at least until they can confirm whether only a particular batch or all rims are affected).

If you were planning on running 4000s, I’d be happy to supply and fit a set of Schwalbe Ultremos for 25% off.

Dated 27/08
2011 Scott Addict R3 (DA groupset, Tune Skyline RR wheelset, Rotor 52/36 Q-Rings)
2008 Giant Trinity A1 (cheapass 50mm carbon clinchers)
No easy road goes anywhere worth going

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WMW
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by WMW

Stan emailed me just a few days ago, so I'm guessing he decided not to ban the use of GP4000s.
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dmp
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by dmp

No problems here. Probably only about 400mi so far on my new wheels with new version 340's, 2 layers of Stan's tape, Michelin PR3's. I started running them at 96psi, but have gradually decreased that to about 85psi (I weigh 59kg). I have had them out in some pretty hot weather here, too. My wheel builder and LBS rave about the rims, so I imagine that they haven't had problems either.

SpoonMan
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by SpoonMan

I get the impression that the conservative approach was from Tune's side - not Stans...
2011 Scott Addict R3 (DA groupset, Tune Skyline RR wheelset, Rotor 52/36 Q-Rings)
2008 Giant Trinity A1 (cheapass 50mm carbon clinchers)
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prendrefeu
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by prendrefeu

Just to chime in (not sure if it will help) -

Two layers of Yellow (21mm) tape on both rims, 20/24, GP400s, Continental Supersonic tubes, never a problem with tire blow-off.

Only once a rim failure on the rear (after too many miles to count), replaced to the newer heavier rim, no other problem to speak of.
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WMW
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by WMW

I've had several GP4000s mounted without incident as well. The one that came off I had noted as being a bit loose the last time I'd installed it. It went for several hundred miles after that before coming off.

One thing that is puzzling about this is how they seem to come off randomly. If it was a problem with the bead being loose, wouldn't you expect it to happen when there are high temperatures from braking on technical descents (something I do), plus cornering forces and bumps? Don't get me wrong... I'm *really* glad it didn't happen then... but why the hell would it happen when cruising at low speeds... or sitting in the garage?
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athos
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by athos

I use a single layer of 12 mm tape and GP4000s tires. Not had a problem, didn't know I need more tape. Just took a tire of last week for the first time after installing it (no flats) and I noticed how well the bead was seated in the rim.

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bikerjulio
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by bikerjulio

athos wrote:I use a single layer of 12 mm tape and GP4000s tires. Not had a problem, didn't know I need more tape. Just took a tire of last week for the first time after installing it (no flats) and I noticed how well the bead was seated in the rim.


When I first built mine up, I hadn't got the right tape and with velox noticed how any tape that got caught on the "shoulder" of the rim could interfere with bead seating. Then I searched their site and found nothing about using these with tubes and clinchers. When I saw the "21mm" tape thing I assumed it was a typo and meant "12mm" since that happens to be exactly the width to cover the "valley" without going on to the shoulder. (and Stan sells 12mm tape btw).

So, I've been using a single layer of 12mm tape for 10 months now without problems. I don't know if their site has improved in this respect but back last winter there was virtually no info on road setup with clinchers. Still don't understand why they call for 21mm.
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Briscoelab
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by Briscoelab

I've seen a couple sets of Hutchinson tubless road and CX tires blow off of stan's rims.

I had a set of Fusion 2's that had cracks all along the tire bead. It didn't blow off, but if I would have let it go much long... it likely would have. This was the same thing that caused the other tires to come off.

I've never had any issues using the wheels with regular tubed CX or road tires. I use one layer of the wide tape.

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WMW
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by WMW

bikerjulio wrote:Still don't understand why they call for 21mm.


I didn't at first. It's impossible to keep tape out of the bead socket with 21mm tape. Which is why I've normally used two layers of 12mm for tubed, and one 12 one 21 for tubeless (to seal the rim) and then I use a razor knife to cut off any that gets in the bead socket.

But according to Stan himself, two layers of tape on the "bench" (the flat part of the rim) is intended to make the bead tight... and having tape in the socket doesn't really matter. Two layers of tape (vs none) adds >2mm of linear stretch to the bead. I'm not sure who much difference that makes but it could be significant.
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by WMW

Briscoelab wrote:I had a set of Fusion 2's that had cracks all along the tire bead.


That's interesting. Would you say that the carbon fibers in the bead were breaking?

Nothing looks funny with the kevlar beads on the tubed tires, but they certainly get a lot looser after they've been on the rim awhile.
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Franklin
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by Franklin

An expensive rim which has flaws which can lead to scary results.

Any reason to pick this ne over the Kinlin XR-200?

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