Tech Tips
| The Spoke Wheel Dilemma |
 |
| Part Two |
| "Going Tubeless" |
| By: Larry Diaz |
In
the first part of "The Spoke Wheel
Dilemma," I addressed the problem of wheels that seemed
impossible to balance and the efforts made to come up with a smooth ride.
My next goal is to make my spoke
wheels accept tubeless tires without inner tubes. For most of us, it has
been quite a while since we have had to deal with tube tires. I was
talking with a friend and we seem to remember that the tubeless tire
became standard in the middle sixties. For most of us it has been around
thirty-five years since tube tires. We tend to forget the headaches
involved with them.
Flats are a bigger problem with tube
than with the tubeless. If you have a flat tire with a tubeless tire, the
tire is simply plugged, pumped up to proper P.S.I. and you are on your
way. If you have a flat with a tube, it becomes more bothersome. The tire
must be taken off the rim for the repair to take place. For those with the
spoke wheels, the process of taking the tire off the rim adds wear and
tear to the rim. With the use of pneumatic tire changers, the likelihood
of warping or bending the rim is even greater. The tube must be patched
and reinserted into the tire. Thirty-five years ago any service station
Another problem with the tube tire is
the tube itself. In the sixties there just were not that many tire sizes.
There were the standard 13, 14, and 15-inch tire size. Within these sizes
there were a few variations but nothing like there is in 2003. Tubes were
plentiful for the available tire sizes. This is not the case today. If you
can even find a tube that fits, for example, a 14-inch wheel, it will fall
within the one-size fits all categories. As a result, you may end up with
a 15-inch tube in a 14-inch rim. This will happen because this was the
only tube the attendant had to put in your tire. In due time you
Flats with a tube tire have different
characteristic then flats with the tubeless. Once a tube tire starts to go
flat, the driver has very little warning before the tire is completely
flat. It has been my experience that you have just enough time to make an
emergency stop if you are running interstate speed. If you have ever had
to do this, you know this is not a safe situation to be in, especially in
heavy traffic. A tube tire gives warning. They have a tendency to go slack
and the driver can feel the car wobble a bit before all control is lost. I
could go on with the advantages of a tubeless tire but I believe the point
is made.
Now about the business of making a
spoke wheel tubeless. The problem with making a spoke wheel tubeless is
the rim itself. On a MGB like mine, there are sixty spokes that come
through the rim. Each place in the rim where the spoke is inserted is a
nipple. This area is not an airtight seal. To make things worse, the spoke
itself is threaded into this nipple. The treaded spoke into the nipple is
not airtight either. In one wheel there are 120 spots for air to leak out.
I decided to try to seal these trouble spots. In my first attempt I took a
hand wire brush and cleaned the nipple surfaces on the inside of the rim.
I had a tube of 100% silicon, the type that goes in a caulk gun, and
covered each nipple. I then let it set for a day, put a tire on it and
pumped it up. I checked and had 7 leaking spokes. At first I was
disappointed, but then I realized that if ever a teacher in school gave me
a test with 120 questions on it and I only goofed up on 7, then I was
happy (At least I think I would have been because I never achieved that
rate of success). I decided to move forward with what now I considered a
successful test. I took the tire off the rim and got my side grinder out.
I put on a wire wheel and really cleaned it, smeared on the silicon, let
it set and pumped it up to 45 PSI. That
was over four weeks ago now and it still has 45 PSI. I am now confident
that I can get a tire to hold air just lying around the shop. Going down
the road presents a different set of problems. My concern was the sealant
might come loose due to vibrating or heat buildup so I decided to change
the sealant. I bought a substance with the brand name of Lexel. It has
silicon type characteristics but with better adhesion properties. It also
had a wider temperature range when applying.
It
could be applied in temperatures as cool as 0 degrees Fahrenheit and as
hot a 135 degrees Fahrenheit. I thought that once it cured, it would be
able to exceed this temperature range. It also can be painted. This helps
because once the paint is applied, any area not sealed shows up as not
being painted. I also went one step further in the cleaning process.
Instead of cleaning with a wire brush, I sandblasted. After sealing with
Lexel, I let it set up for three days and put the tire back on the rim. I
pumped air into it and have road tested it for fifty miles or so. So far I
have not lost any air and it seems to be holding up fine. All I need to
happen now is for this to stand the test of time
and the heat of summer. My plan called for me to do this one tire and test
it throughout the summer driving season that includes extra driving miles
complete with road heat. My first real outing was a planned club trip to
Maggie Valley, North Carolina after our March club meeting. This trip
would have put around one hundred fifty miles on the tires.
Notice I said would have. Not one mile on our planned journey, I
had another flat tire. The cause was another fold in the inner tube in one
of the three tires that still had tubes in them.
I parked the car at a nearby restaurant, and my wife and I
continued the trip with a fellow club member in their Rover. After
returning home, I did not bother to repair the inner tube. Instead, I made
this wheel tubeless like the other.
It is now May and my wife and I are
going to West Virginia from South Carolina.
I now have two tubeless tires that have held a constant air
pressure during the past three months.
I am encouraged because not only has the air pressure held constant
for such a long period, it has also included quite a few miles driven
locally. I am confident that the tires will not present a problem for us,
but just in case, I have two inner tubes in the trunk!
We have made it back from our West
Virginia trip. I am happy to report that in over 900 miles of mountain
driving, we did not experience a tire failure. I guess now I can consider
this experiment a success and will convert my remaining wheels to
tubeless.