What kind of tire plugs?

Discussion in 'Equipment' started by dcwn.45, Mar 30, 2008.

  1. Terry

    Terry Long timer

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    A while back I got a small hole in a Tourance rear tire, followed a week later by another. I plugged both with the el-cheapo "Monkey Wrench" strings and rode for a month or so on them. A few hundred miles maybe. Both held up fine and didn't leak down at all.
    When I changed the tire (did it myself), I looked at the repairs from the inside. Both were still in place pretty well. One of them would not pull out from the inside no matter how hard I pulled. The other came out fairly easily when pulled from the inside.

    I would still consider them a "temporary" fix. If I intended to but a few thousand more miles on the tire or ride all day at highway speeds, I might consider taking it off the rim and patching it from the inside. Better yet, I'd probably put on a new tire unless it was like almost brand new and I wasn't "rollin' in dough"...

    I'd like to know more about the "improved" version with the raw rubber strings, but the site isn't working.

    I do worry about the strength of the steel cords after I have mangled them enough to get the string in. Seems a shame to take a little tiny nail hole that is just barely leaking at all and ream it out into a much larger hole that requires cutting a bunch of the steel belts. Not much of a worry at low speeds, but at higher speeds, I'm kinda counting on the steel belts to hold the tire together...

    Someone should come up with a glue or something that could be injected into a small hole that would "melt" the rubber back together and seal the puncture without having to rip the belts apart to put in a big ol' plug or string.

    Someone invent that. Just remember I thought of it first...:rofl

    Terry
    #41
  2. VStromTom

    VStromTom Long timer

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    I will continue to use the string plugs whenever I think they will work, and if not I will do something else to get me where I can decide to do something else. Many of us have ridden thousands of carefree miles with plugged tires. Don't use them if you don't want to Cody, but please, no more lectures about them not working or being unsage. You do your thing, those of us who know they work, will continue doing our thing. Peace Bro!
    #42
  3. bonox

    bonox Tryin Hard

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    no physics degree for you!
    #43
  4. bonox

    bonox Tryin Hard

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    [​IMG][/IMG]

    look at a basic tyre - lets assume the rear of a GS - 150x80-17.

    Total diameter on the inside (ie ignoring the thickness of the tread wall, because the internal pressure doesn't act on it), you have about a 17" + 2*4") diameter - ie 25". Since 150mm is about 6", lets just use that.

    Looking at half the tyre, you have a total load produced of pressure (P) * projected area. ie 30psi * 25"*6" = 4500lbs.

    Ignoring the shear loads through the tyre sidewall (giving rise to reactionary loads R3 and R4), lets just say that all the load is taken by the tyre carcass that supports the tread (R1 and R2). You now have a 2250lb load in the carcass (equal top and bottom as R1=R2).

    Take a look at the construction of a tyre (eg http://www.freepatentsonline.com/7094302-0-large.jpg). Michelin say thier tyres have between 2 and 4 plies of radial kevlar and another 2-4 of cross nylon or similar.

    Since the plies in the circumferential direction are handling this load, we only analyse them. Lets say there are 100 cords across the ply. A puncture takes out 2 cords per ply.

    Thus we have 2ply*(100-2cords per ply) = 196cords to support 2250 lbs. (divide by the cosine of the ply offset if not zero degree belted).

    You now have 2250/196 = 11.5lbs per cord. A tiny fraction more than the tyre without damage. Compare this to the breaking strain of nylon fishing line, and it is a pitiful load. Kevlar and steel have much greater tensile stress capability to boot.

    Where is this bomb you are talking about? That will only be in compressed gas and elastic strain energy - both of which are pretty negligible at 30psi anyway, and the advantage of a tubeless tyre is that it tends to seal around a puncture object, preventing explosive release of the contents - why the flamboyance of 12,000pounds of pressure? There is only 30 pounds of pressure per square inch of applied area, or 2250 lbs of force in the whole tread wall, but it is distributed across the area of the plies, and so the working stress in the tyre is actually much lower than in the bridge you are driving over, or even the engine mounts and floor beams of the car or bike you are driving.
    #44
  5. wibby

    wibby BrotherFromAnotherMother

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    I temporarily fixed my last tire for abot 9,000 miles :wink:
    #45
  6. bonox

    bonox Tryin Hard

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    slime does exactly that.

    For a more rigorous approach, look up 'self sealing fuel bladders'
    #46
  7. GSWayne

    GSWayne Old Guy nOOb

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    Slime clogs a hole with a bunch of fibers and goo. The blob is mainly on the inside surface of the tire. It does not really fill the hole, so dirt and water can definitely get into the hole in the tire to the belts. I think he was envisioning something that filled up the entire hole.

    I use Slime a lot on bicyle tires and it works great on small holes, like from thorns, but if you get a hole too big for it it makes a gigantic mess when it sprays out the hole all over you and the bike, which has happened to me twice.
    #47
  8. gc916

    gc916 Adventurer

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    I use Ride-on tire sealant. Same concept as Slime, I guess, but without the mess. No adverse effects on handling or wheel/tire balance. At my last tire change, the tech was amazed that the Ride-on had coated the tread area inside the tire, but had not created any problems with the tire changing process, no wheel cleaning necessary, etc.
    I haven't had the need to check out the sealing properties (yet), but from all reports, this stuff works.
    Usual disclaimer applies.
    #48
  9. Jeffro115

    Jeffro115 Redemption.

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    I'm definitely in the minority here, and this thought is pretty old school.


    But riding on a plugged tire is suicide IMHO.


    I know that there are tons of people that do it.




    I might do it just to get down the road to a shop. But even if it were a brand new tire, I'd replace it with a good one. I have a lack of confidence in a plugged or patched tire, and when I'm on two wheels, I want everything to be right.
    #49
  10. CodyY

    CodyY ADVenture Capitalist

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    This is what i've been trying to get across, apparently to little success.

    I've said my .02, Ride on.
    #50
  11. eric2

    eric2 ®egister this:

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    Well, nothing like a little pissing contest over tire repair.:rolleyes I've had bad experiences with the stop n go system, but they did have a run of bad plugs i'm told. The goopy cords have worked most consistently for me, they pack well too. Currently running a plugged rear tourance that has over 10k miles on it. About 8k with the plug. I wouldn't use slime either, unless you don't mind the mess it makes. Good way to get on your tire installer's bad side.
    #51
  12. gc916

    gc916 Adventurer

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    I agree completely. My earlier post regarding Ride-on was meant to point out a very temporary fix to get me to a new tire.
    #52
  13. Terry

    Terry Long timer

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    Good write up! But what about the centrifugal ( know, no such thing) force from the tire rotating at 105 mph (not that I, personally would EVER drive that fast, since that would be illegal and I am a law abiding citizen :rofl ). I thought the belts were more intended to keep the tire from coming apart at speed.

    I know it seems like losing a couple of threads out of a hundred or more is an insignificant percent of the whole, but isn't it like a rope where losing a few strands causes a "chain reaction" that just keeps causing more and more to fail?

    Obviously, I don't have a clue what I'm talking about :lol3 , but these would be the thoughts going through my head the whole time I was hauling ass (at legal speeds of course) down the highway with a repaired tire....

    Terry
    #53
  14. R1200R Lover

    R1200R Lover Gunslinger

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    What did you guys think of my stopngo write up on page 3??? For you folks that say the tire will fall apart and explode and collapse into a black hole and kill everyone, what do you think? I had FOUR plugs in the back tire and one very near the sidewall of the front tire and was taking the bike past a ton several times in the course of a month. I think you need to realize that a modern tubeless tire is far tougher than inner-tube tires of the old days. As for stopngo, the shit works, so long as it has been properly installed and it's a round hole. Think of it this way: it's worked FIVE times out of FIVE for me under normal full out riding conditions.

    Tip for stopngo people: don't be afraid to pull hard on the plug stem to set it. Use pliers. Also, and very important here: DO NOT cut the stem flush with the tread. It will wear down eventually, but I had a few fall in the tire when cut flush, before I figured it out. I believe it's held in place by friction and by pressure from a full tire.

    Having said all that, I still carry the goopy linguini as a backup!

    Who's got experience with Ride-On that actually got a flat?
    #54
  15. rdsmith3

    rdsmith3 Long timer

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    I realize that I only partially understand the physics you presented, and I realize that you were correcting codyY's miscalculations, but I think you are missing something important.

    The above seems fine for a static tire and, really, whoever heard of a static tire blowing a plug?

    However, when a tire is in motion, it is flexing. I humbly submit that this makes the physics much more complex. More importantly, the puncture is flexing, possibly changing shape and diameter. Over time and miles, I am assuming this could potentially lead to air leaks and/or losing the plug. I realize that motorcycle tires do not flex as much as the sidewall of a car tire, but there must be some movement.

    Temperature changes due to motion would also affect the size/shape of the puncture, the ability of the plug to adhere to the hole, and the pressure within the tire.

    All this means it is far too complex for my brain to figure out, but I would not completely trust a plug if I were about to attack some serious twisties.
    #55
  16. Terry

    Terry Long timer

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    I've never used the stopngo, so I can't really say. I don't think I like the idea of having to pass that big ol' button part through the hole. Do you end up making a bigger hole because of it?
    I do know I've read many stories of people having trouble with the stopngos here on ADVrider. Both trouble getting them in, and trouble with them coming out after a few miles. Probably a matter of improper technique, but more people seem to have issues with the stopngo than with the strings. That's why in my "emergency kit" I carry the strings. They seem to be fool-proof enough that even a clod like me can fix a flat and have at least a temporary repair 'till a new tire can be fitted.
    I use the green slime stuff in my lawn tractor tires. They are so full of holes and even cuts that it amazes me that they hold air at all. The slime really works well. I have no doubt that it will seal a puncture. At least when fresh. But after a year or so? Not so sure.
    Also, I would like the chance to know I've got a puncture or cut, inspect it, repair it, and decide how much farther I should drive on it. With the run-flat or slime apprach, you might be driving around on pretty cut up tires. I know all the rest of you guys all inspect your tires before every ride, but we are talking about me here :rofl .

    Terry
    #56
  17. GSWayne

    GSWayne Old Guy nOOb

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    But should I use Dino strings or synthetic strings?:D
    #57
  18. dwf

    dwf 2007 R1200GS Adventure

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    #58
  19. bonox

    bonox Tryin Hard

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    the stresses don't change because of the plug - the role of the plug is to fill the hole and stop it leaking - it isn't there to repair the damage to the carcass. The reason you use the cement on the patch is to seal the patch to the original tyre. Structurally, load will go where the stiffness is. The intact cords around the patch are much stiffer than the patch, therefore there should be approximately zero hoop load imparted to the patch, and it only sees the air pressure load.

    The carcass of the tyre also acts like a composite structural material (fibreglass or carbon fibre) and are quite damage tolerant. In fact, the job of the rubber is really to protect the cords, and to transfer the load straight into the fibres - the rubber itself doesn't carry significant loads. What does happen though, is that when you break a cord, that part of the tyre becomes more elastic (higher local strains) and the load then gets shed into the stiffer adjacent cords next to the break. Your biggest problem now becomes fatigue or just plain tensile overloading in the cords adjacent to the damage. Kevlar and nylon don't have tensile fatigue properties like steel does, however you have to remember that if the increase in local load seen by the fibre isn't enough to exceed its fatigue stress for the number of cycles the tyre will probably see, then nothing will change. As long as the plug is more flexible than the tyre carcass around it, and you managed to cement the whole face of the repair, then you shouldn't have the plug leak for the life of the repair - (by that I mean a reasonable life, not running it down to the cords before replacing it or leaving it in the shed for 20 years and then deciding that it's still a good tyre to use!)

    THe other point is that if you have a tyre with mostly 0 or 5 degree belts (ie radial ply racing tyres) there is very little to stop the hole splitting sideways across the face of the tread. If you've had a sidewall puncture or a big stick go through your tread and tried to repair it, you'll have recognised this behaviour. This is the type of damage for which a string (or anything) really is a temprary repair. There is a lot more to a repair than a blanket rule - something that many people seem to gloss over.

    Regarding rotation derived loads in the tyre - For this reason it is never recommended that you use a repaired tyre to its undamaged potential - ie don't plug it and then do racetrack speeds, or here to wollomollo at 200mph. That doesn't mean however that at sane speeds, you can't continue to use a patched tyre - I think the biggest problem some people have with 'temporary' repairs, is that they never take the tyre off and check that the repair was sound (ie you put the string or plug in properly).

    Does this all make sense?

    There is analysis in why i'll ride on a patched centre tread hole made by a screw or nail, but when I got this key (that took three strings to repair so that I could limp home), the tyre went straight in the bin! BTW, the maximum open road speed where I live is 110KM/h, not miles per hour. I'm happy running at that speed - not sure i'd run a patched tyre at 170km/h though!

    [​IMG]

    I agree that a purely static analysis isn't the be-all and end-all, but I wanted to point out that cody's scaremongering of 'omg, truely massive pressures inside, it's a bomb, don't taze me bro' (sorry mate :rofl ) has no scientific merit. As a first approximation though, the tyre is only a single sided balloon. THe centripetally derived loads may introduce a load equivalent to that that should be taken by the bead (R3 and R4). There are also more cords in the sidewall to take acceleration and braking loads that exceed the centripetal acceleration loads and also take pressure derived hoop stresses away from the tread face, so it shouldn't be a super poor analysis.
    #59
  20. KingRat

    KingRat Stroppy.

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    I'm bumping this thread because I need a temporary puncture repair kit for tubeless tyres.

    Given that its purpose will be to let me finish the ride and then replace the tyre, I'm currently tending towards string type repair kits.

    Questions:

    Any more experiences with StopNGo?

    String repairs - insertion tool with slot at tip and no twist to release vs. insertion tool with slot in mid section and twist to release string?

    With strings, to use glue or not (kits seem split 50/50)?

    Best CO2 inflator (no room for electric pump.)

    Thanks in advance y'all.
    #60