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  1. #1
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    New Tire shape/weight (how far from posted spec is ok?)

    What's the margin of error that's acceptable before you exchange a tire? +/- 10,20,30g?

    Or just inspect it and make sure the bead is safe to use?

  2. #2
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    New Tire shape/weight (how far from posted spec is ok?)

    Quote Originally Posted by Deerhill View Post
    What's the margin of error that's acceptable before you exchange a tire? +/- 10,20,30g?

    Or just inspect it and make sure the bead is safe to use?
    New tires? +/-10% for weight is normal, 20% is not unusual. Has little to do with the safety of the tire.

    The only tires I have exchanged had mismolded tread with grossly bare casing threads.
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  3. #3
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    Quote Originally Posted by Deerhill View Post
    What's the margin of error that's acceptable before you exchange a tire? +/- 10,20,30g?

    Or just inspect it and make sure the bead is safe to use?
    Different manufactures have different internal tolerances for weight. Kenda is the only one I've ever seen to publish theirs. (It seems to be around +/-5% of the tire weight).

    I would personally be unhappy with a tire that's more than 15% off, but whether or not that is a warranty issue is up to the manufacturer.
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  4. #4
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    Safety

    Quote Originally Posted by shiggy View Post
    New tires? +/-10% for weight is normal, 20% is not unusual. Has little to do with the safety of the tire.The only tires I have exchanged had mismolded tread with grossly bare casing threads.
    So that 20% (let's say +20%), is it less likely to end up on the bead then?

  5. #5
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    Quote Originally Posted by Deerhill View Post
    So that 20% (let's say +20%), is it less likely to end up on the bead then?
    Weight variance is mostly due to the tread compound extrusion. I would estimate > 90%. Most of the rest of the variance is in the calendared casing fabric stock. Very, very little to do with the beads.

    If they're wire beads, there could be a little variation in how much insulation is added to the wires. If they are UST beads, there could be a slight variation in how much rubber is applied to the bead chafer. Neither of these contributes to the strength of the bead. If its a regular folding bead, almost no variance in weight.

    I have a feeling you're worried about the safety of a particular tire. What's the issue?
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

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    New Tire shape/weight (how far from posted spec is ok?)

    Quote Originally Posted by Deerhill View Post
    So that 20% (let's say +20%), is it less likely to end up on the bead then?
    I included the 20% because some companies quote weights based on the lightest sample of a batch. Others use average weight. Then the weights vary from batch to batch.
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  7. #7
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    Quote Originally Posted by bholwell View Post
    Weight variance is mostly due to the tread compound extrusion. I would estimate > 90%. Most of the rest of the variance is in the calendared casing fabric stock. Very, very little to do with the beads.If they're wire beads, there could be a little variation in how much insulation is added to the wires. If they are UST beads, there could be a slight variation in how much rubber is applied to the bead chafer. Neither of these contributes to the strength of the bead. If its a regular folding bead, almost no variance in weight. I have a feeling you're worried about the safety of a particular tire. What's the issue?
    No issues, was ust thinking out loud wondering where the material ends up. Sounds unlikely to negatively change that profile of bead/rim grip. And I never had a tire even close to 20% off, batch to batch that makes sense over/under. This one is 20g over but it's for a little heavier build so doesn't matter (foldable but dual ply sidewall)

    Thanks for the information and time shiggy and bholwell. Parts are coming in for a new build and this is now making me think about tubeless again.

    Only tried tubeless once, on the rear. Sucked due to user error. I always choose to use tubes but everything seems to be some tubeless flavor..and front wheel pats show up first

  8. #8
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    Quote Originally Posted by shiggy View Post
    I included the 20% because some companies quote weights based on the lightest sample of a batch. Others use average weight. Then the weights vary from batch to batch.
    Thought of this while I put the front together. Also thought about hitting a rockgarden, of off camber turn an high speed, and what little amount of rim material is for the bead.

    Why wouldn't it affect safety if the bead profile was out of spec, or not precise enough? Seems if the shape came out different than designed, it doesn't interact with the rims profile in the same way. Maybe it's more of a safety issue if tubes are not used

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    New Tire shape/weight (how far from posted spec is ok?)

    Quote Originally Posted by Deerhill View Post
    Thought of this while I put the front together. Also thought about hitting a rockgarden, of off camber turn an high speed, and what little amount of rim material is for the bead.

    Why wouldn't it affect safety if the bead profile was out of spec, or not precise enough? Seems if the shape came out different than designed, it doesn't interact with the rims profile in the same way. Maybe it's more of a safety issue if tubes are not used
    Because as b said, most of the weight variations are in the tread and casing.

    Weight is not an indicator that the bead shape is out of spec.
    If the bead is misshapen it would be obvious and should never make it out of the factory.

    You also bring up one of the reasons I do not recommend using any standard tire and/or rim without inner tubes. Just not designed to do it safety.
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