patching radial tires- LONG...?

I ran into an interesting problem, and im not sure exactly what
happened. i had a tire (bridgestone "hoop" 13", 3 ply nylon) with 2
small punctures. one was a drywall screw, and the other looks like a
small trim tack or nail.

Took the tire off with my Harbor Freight tire remover, which I bought
special for the occasion. I then patched both holes with Monkey brand
radial tire patches. buffed the areas, applied the cement, waited til
dry (i THINK, and this is where i may have screwed up), then peeled off
the backing and applied the patches. i did not use a "knitting tool" and
this is another thing i may have done wrong.

Anyhow- both patches held for about a month, then i noticed a slow leak
after work yesterday. put air in, got it home, put "slime" in for the
time being. Probably shouldnt have done that either, since i knew id be
taking the tire off to see WTF went wrong.

Today, i took off the tire, and both patches were completely off in a
bed of slime, and had some rubber cement gobbed up on em.

So i take this OTHER tire i have, which had a nail go through it and
patch that for the time being. i have a new tire ordered, but its on
backorder and will probably be a week.

this one has ONE hole, and I used a "monkey brand" patch/plug combo.
made sure the tire was clean, installed the patch/plug (which does NOT
require rubber cement), pulled it through, "knitted" it, cut off the
plug end. So far, so good.

Still wary from my previous patching experience, i installed an even
LARGER radial tire patch over the patch/plug combo. Buffed the whole
area, applied rubber cement, installed patch, knitted as directed.

Now, the questions:

What could have caused both original patches to not hold?

Is the patch/plug combo better than a regular patch?

Did i screw up by putting another patch over the patch/plug?

Would adding "Slime" now be a bad idea or cause the patches to fail? if
anything, i think it would add an "early warning sign" that the patch
isnt working.

Yes- i know what im doing is potentially dangerous, but i do have
another tire on order and plan on replacing it ASAP. What i dont
understand is why what has worked for MANY other people in the past is
not working for me, hence the questions.

 

Patches are supposed to be applied when the cement becomes tacky. Then
inflate the tire to the same pressure you'd use to seat the bead, maybe
50 to 60 psi?

The pressure should force the patch firmly down against the inner
liner.

Slime contains propylene glycol, which is mildly corrosive. It will eat
the paint of your rims and it will etch and pit aluminum if you leave
Slime in a wheel for about two years.

I put Slime in a wheel and stored it for 7 years. The aluminum was
deeply pitted.

The rubber cement that comes in tire patch kits is probably a latex
rubber that doesn't stick well to synthetic rubber. My bicycle tire
patches always worked better on natural rubber tubes.

When you look at the inner liner of some tires, it's tan-colored. I
think that is natural rubber. But other tires have a black colored
rubber on the inside with a thin layer of white on top of the black.

I suspect that is just synthetic rubber and you're seeing the carbon
black and the talc used in the molding process.

Like, if you were going to bake a pie and you didn't grease the pie
pan, you'd throw some loose flour in the pan and put your pie dough on
top of the powder so it wouldn't stick when you baked the pie.

Same thing with the talcum powder, rubber glue can't stick to that
stuff.

 

FWIW, I had a nail in my almost brand new rear tire last summer. Took the
wheel off and dropped it off at a local dealer. For $25Ca they put in what
they called a mushroom patch, claimed that would be the end of it, and so
far it's been OK.

If it leaks, thier fault. I carry a little 12V pump when I leave the city
anyway, and I've that heard you can drive on a flat if you have to if you
are at hwy speeds, the centrifugal force keeps the tire round 'nuff,
although I've never tested this theory.

I had a plug kit with me, but there was no way the insertion tool or the
reaming gizmo would go thru the hole.

Luckily I was at home when I noticed the problem.

P.

 

Kinda thought there might be a problem with this

This came from someone I was talking to once who told me that he had
developed a flat out on the hwy and didn't really notice it until he slowed
down.

His version is it he got back on the bike, being in the middle of nowhere
and having not much choice, and over a certain speed the bike was quite
driveable.

Like I mentioned, I have never checked this out myself, but would try if I
was stuck out someplace.

Maybe we need a MC version of Snopes.com

P.

 

The patches should have been applied BEFORE the cement dried
up. The purpose of the cement is to partially dissolve the surfaces.
As it hardens, the patch is "welded" to the tire for an air-tight
seal.

 

hm. the instructions said to apply a thin coat and wait until it was
dry. which didnt take long, since that rubber cement dries pretty fast.
im thinking i maybe used too much, and it DIDNT dry. but maybe it did
and it shouldnt have?

 

14 years ago when I worked at a service station too many years ago then
I want to think,we used to get tires in that the compounds were pretty
tough to get a patch on to stick properly what one of the old guys there
showed me was to put the cement on both the tire and the patch even tho
the patch was sticky the cement help to seal a lil better and stick alot
better but it was only needed on only tires of certain compounds ,but I
also just thought of is did you clean off the the area you ground with a
special cleaner to remove the rubber dust from the area to be patched
that could've been a major part of you problem too , the stuff we used
then came in a metal can and was a cleaner and a primer too ,but can't
remember the name of it, hopefully someone here can help by remembering
what the possible name of this product was ,I just know it worked
wonders and we never had a tire return with the same repair needing to
be done again

 

Blmiey. Not good. Are you sure it's the tyre gunge and not just normal
atmospheric damp or something?

My experience as well.

 

The rubber inside a tubeless tire is different than any other as this is
the only rubber that is formulated to be air tight. Tread and sidewall
rubber is porous.

 

Why not?

As you said yourself, you didn't notice the flat 'till you slowed down.

Why wouldn't hopping back on the bike etc restore the conditions which made
your flat not apparent to you?

P.

 

You are kidding right?

I have never found any solid rubber compound be porous.

If you have a cites to prove your assertion please post them.

pierce

 

Bridgestone has had "run flat" capability in their tubeless tires for
twenty years now.

There is a .pdf file on the Japanese language Bridgestone site. The
file you want to download is called something like Introduction to
Motorcycle Tires, something like
mcintroe.pdf because it's in English. Google and learn, Grasshopper...

Anyway, Bridgestone talks about their work in developing a tire with
"run flat" capability.

The tire is kept on the rim by a strong steel wire bead and the
tubeless rim has special bead retainer ridges to keep the bead where it
belongs. Even if the beads do slip into the drop center of the wheel,
the thick carcass in the tread area will still support the weight of
the motorcycle on sheer stiffness of the rubber plies.

The tire has special hard rubber sidewall reinforcers in the flipper
strips.

Tire engineers became aware of the impossible job of a conventional
telescopic suspension system when GP and sport motorcycles are operated
at 45 degrees or even 50 degrees from the vertical. The suspension
system cannot deal with the out-of-plane loads, so road racing tracks
must be billiard table smooth.

The tire engineers began to tailor those special hard rubber sidewall
reinforcers to act as rubber springs to absorb small bumps while the
machine is leaned over.

And, if the tire should deflate in ordinary highway service, the hard
rubber sidewall reinforcers help keep the tire from collapsing. But, if
the beads slip into the drop center of the wheel, the job of supporting
the motorbike's weight is all on the stiffness of the
plies under the tread area.

The actual radial or bias ply carcass in the area of the tire tread may
be fairly thick, as is Dunlop's usually practice, or it may be very
thin as Michelin tires seem to be built.

The last Michelin I ever bought was a @#$%^ M59X. The Metzeler factory
had just had a disastrous fire and there weren't going to be any new
Metzelers made for several months. They had to make Pirellis first.

So I bought the damned Michelin. I looked at the carcass and saw how
thin it was. I thought to myself, "I'll bet I can turn this @#$%^ tire
inside out, just like a bicycle tire".

So I did. I turned the friggin' tire inside out! You couldn't do that
with a Metzeler, Pirelli, Dunlop, or Bridgestone, their carcasses are
too rigid for that kind of foolishness. I only got about 2000 miles on
that @#$%^ Michelin before it was punctured. And it was unpatchable due
to a strange raised pattern inside the tire that prevented a patch from
sticking.

But I would certainly trust a Metzeler, Pirelli, Dunlop, or Bridgestone
tire to run flat long enough to get me to a service station.

 

Have you ever noticed how small white crystals form around the lid of
your brake or clutch master cylinder and the paint is attacked if the
rubber seal around the lid allows brake fluid to weep out?

Ethylene glycol and propylene glycol are hygroscopic, they will absorb
moisture from the air and the glycol will crystallize and the aluminum
around it will be etched.

How does a practical street rider inflate his tires anyway? From the
compressor at the service station. He has no control over the amount of
water in the air. He's unlikely to buy a cylinder full of dry nitrogen
to inflate his tires.

So you do have a point about the role of dampness in the air. But Slime
is still alkaline and hygroscopic.

Thr first time I heard of Slime being corrosive was when an ATV owner
posted a warning. He said that Slime had eaten holes through his spun
aluminum wheels.
He complained to the manufacturer, and they claimed it was impossible.
However, they wanted his wheels for a forensic inspection.

I already had Slime in the rear wheels of two machines, so I bought a
bottle of Slime and immersed a small aluminum spoon into it and left it
for 30 days. There was no evidence of etching on the test specimen.

I have a box of pH test strips that I used at the cogeneration plant
for testing the alkalinity of steam in the condensate system.

So I put a pH test strip in the Slime and found that it tested pH 8.0
to 8.5, definitely alkaline. But, in the absence of etching on my
aluminum test speciment, I thought I could leave Slime in the rear
wheels of the motorbikes for a while.

When I finally wore the rear tire out on the bike that had Slime in in
for two years, I discovered that Slime had removed the paint in several
places and had begun to etch the aluminum.

And, the wheel that had Slime in it for seven years was deeply pitted.
While stored with
Slime inside, the tire had eventually deflated, and the bead had
actually broken loose, so the inside of the wheel was definitely
exposed to damp air. This may have been a factor in the corrosion.

There's another company that makes a similar product to Slime and a lot
of riders are using it. I disremember the name at the moment, but it
also contains propylene glycol to avoid freezing. They claim that their
product has chemical buffers in it to avoid corroding the aluminum.

 

Blimey again.

Impressed.....

 

You are kidding right?[/QUOTE]

Dead serious. All material is porous to some extent. Rubber is more
porous than popular perception believes. Popular perception wants to
believe everything is either black or white, nothing in between or
beyond.

You never seriously tested.

Only reference I have is a former Dunlop tire engineer I used to ride
with. He said that the inner coating is formulated specifically to hold
air, much the same as innertube rubber is formulated. That a tube-type
tire will never hold air very well no matter how one seals the bead.
That when repairing a puncture a plug thru the carcass only prevents the
cords (possibly steel) from rubbing each other and making things worse,
the air seal only occurs on the thin layer inside. Lots of goo on a
string plug, push it thru, then pull it back out a bit so as to form a
puddle of goo around the string on the inside to form the air seal. This
is why a simple plug doesn't always hold air, and why a T-plug from the
inside is the only reliable repair.

 

Dead serious. All material is porous to some extent. Rubber is more
porous than popular perception believes. Popular perception wants to
believe everything is either black or white, nothing in between or
beyond.

You never seriously tested.

Only reference I have is a former Dunlop tire engineer I used to ride
with. He said that the inner coating is formulated specifically to hold
air, much the same as innertube rubber is formulated. That a tube-type
tire will never hold air very well no matter how one seals the bead.
That when repairing a puncture a plug thru the carcass only prevents the
cords (possibly steel) from rubbing each other and making things worse,
the air seal only occurs on the thin layer inside. Lots of goo on a
string plug, push it thru, then pull it back out a bit so as to form a
puddle of goo around the string on the inside to form the air seal. This
is why a simple plug doesn't always hold air, and why a T-plug from the
inside is the only reliable repair.[/QUOTE]

Some googling will yeild this info..

It's not so much the material being porus as nitrogen can diffuse thru it...

It's like why party balloons deflate after a while...

An eg is... Balloons designed to be filled with helium have a foil layer for
this reason, to slow down the escape of the contents thru diffusion...

The lining layer in tubeless tires is meant to slow this down by the same
token...you can check it out if you want....

My 0.02...

P.

 

I have contended for years that the inner coating of a tire is
self-healing if the puncture is small enough. Of course the tire
manufacturers ran all those commercials on TV showing how tires would
continue to hold air after being punctured with multiple nails, and
airplanes fly around with self-sealing rubber bladder fuel tanks inside
their wings.

But the first thing a tubeless tire plugging kit's instruction sheet
tells the rider to do is to bugger the small nail hole out to about 1/4
of an inch in diameter so he can stick a much larger plug or gummy worm
into the hole.

To my mind, this is idiocy. If the hole is only about 1.0 to 1.5mm in
diameter, my contention is that the sealing rubber liner might just
close up and stop the leak automatically after the nail is removed.

And even if the hole doesn't completely close up, it will be so small
it can be filled up by the liquid latex that comes in a can of Seal N
Air.

I've been told many times that the tire apes in the $tealer$hip$ don't
like that aerosol stuff because the propellant gas is flammable. And,
my answer to one of those guys would be, "Don't light up your crack
pipe while you're working on my wheel!"

Actually, I change all my own tires, and I haven't noticed any problem
with flammable gasses of latex mess.

 

The stresses in a tubeless tire help serve to pinch the hole shut and
minimize leaks. This is one of the reasons tubeless tires are safer than
tube tires. A tube lacks the internal stresses to pinch a hole shut so
it goes flat in seconds with a puncture.

Some manufacturers have made tires with a thick gummy inner coating
which serves to self-seal punctures.

 

Well, I wish I knew of a gummy liquid which didn't have a solvent with
a high vapor pressure or a water-based solvent that would freeze. I'd
squirt about a pint of the stuff in my tires if it would stay liquid
and not raise the air pressure inside the tire.

Is that asking too much?

 

I want to say thank you for that very informative and intelligent
response to this ,some people will come in and say don't use it and
don't give a response why not to use it ,the best info is the most
complete info and best experience possible to make a good determination
to use certain products ,some alloys cannot have certain chemicals on it
since different aluminum alloys is more ,shall I say, sensitive to
certain chemicals then other alloys.
again thanks for that response