THE LOW
PRESSURE REVOLUTION
Excerpt from STAUN U.S.A.'s website by
Harry Lewellyn
Staun Products' Internal BeadLock™ is creating a low tire pressure
revolution, and I'll tell you why throughout. Words alone don’t do
this product justice. Even if you don’t read on, take a look at the
pictures. They are very impressive!
If you play in the dirt long enough, you will eventually encounter
rim- , tire-, bead-related problems. Popping the beads off the rims
is relatively commonplace. While playing and learning about sand
years ago, I actually popped four beads at one time! I was
side-hilling. I lost the two outside beads on the downhill side, and
the two inside beads on the uphill side.
Another problem is spinning the tires on the rims. That results from
too much traction and torque, and not enough friction between tire
and rim due to low tire pressure. These annoyances are expected by
the folks that regularly play on the Black Diamonds. Up until now,
they counter these rim/tire/bead predicaments in several ways.
However, Staun's BeadLock™ may make bead-related problems a thing of
the past at any pressure.
The Black Diamond guys may (1) install conventional bead locks or
(2) sacrifice performance by running higher "low" pressure than they
really want. They may also (3) choose to live with rim/tire spin and
get the wheels rebalanced every so often. For intermittent air
"burping," they usually just (4) add air along the trail and get
used to reseating the beads when they completely knock 'em off.
Staun Products' pneumatic Internal BeadLocks keep the beads in place
and tightly secure the tires to the rims. This means that you can
run exactly the low pressure you want, and as our tests proved, with
no fear of popping a bead or spinning the tire on the rim. Isn't
that worthy of being called a low pressure revolution? And not to
beat it to death, are you aware that there are very light weight
competition rock crawlers that run zero, repeat, zero PSI in their
tires! They, along with every guy who owns 16.5” wheels, need a low
pressure revolution!
Staun Internal BeadLocks provide a way to lock both the inside and
outside tire beads to the rim. No special rims are required. Staun
has sizes to fit everything from 9 inch ATV/Quad rims to behemoth 19
inchers!
DESCRIPTION
A fully LOAD RATED inflated tire stands a 99% chance of having none
of the problems described above. Period! In other words, when
properly inflated, the tires do their job perfectly. That is because
high (street) pressure securely locks the tire bead against the rim
and eliminates air loss and tire/rim spin. The bead/air loss thing
appears to be borne out by the roll tests I've conducted. I've side
tilted 5,000 pound 4Xs, to greater than 45°, with fully inflated
tires, and never unseated a tire bead or lost any air (see Figure 2
and insert).
Wouldn't it be perfect if we could apply high pressure right at the
tire's beads, independent of the pressure in the balance of the
tire? Staun's Internal BeadLock™ does exactly that. It is literally
a specially reinforced mini-tube right next to the bead. By the way,
I use "wheel" to mean the tire (rubber part) mounted on the rim
(metal part).
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DESIGN
PRINCIPLE
Very simply put, a Staun Internal BeadLock™ divides the innards of a
tubeless tire into two air chambers. The one nearest the beads holds
rubber to metal. This means the remainder of the tire's air space
can confidently be inflated or deflated to any pressure you desire
baring blowing it, up of course.
So how does a conventional bead lock differ?
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CONVENTIONAL VERSUS STAUN'S BEAD LOCK
Conventional bead locks mechanically clamp the outside tire bead to
the rim, always, and rarely, the inside. They do a 100% perfect job
at that. Staun Internal BeadLock locks both the inside and the
outside beads to the rim. Although it is less common to lose the
inside bead, it nevertheless happens. Proof in point: Prior to
installing Staun Internal BeadLocks, Blaine Johnson was used to
regularly and undesirably burping air out of a rear, conventionally
bead locked wheel. With the Stauns, the problem vanished.
Conventional bead locks can be difficult to balance. As Figure 3
shows, the conventional bead lock puts all of the weight on the
outside of the wheel, only. That's typically a ring plus 24 cap
screws and washers. This could make for balancing problems. But on
the plus side, this ring protects the vulnerable valve stems.
Staun Internal BeadLocks are light weight (about 5 pounds for
fifteen inchers) and the weight is evenly distributed from the
inside to the outside of the rim. Further, since some of the weight
is nearer the center of the rim, it minimizes imbalance effects.
There are no balancing problems with Staun BeadLocks.
If you drive on a conventionally bead locked flat, you stand a good
chance of damaging the rim, tire or both. The Staun BeadLock tube
and case add height to the flat as if it were not flat, and in fact,
that is actually what’s happening. A portion of the tubeless cavity
still contains air at high pressure and keeps the rim off the
ground. It does not let the rim pinch the tire at the ground (see
Figure 4).
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BEAD LOCK LEGALITY
Regarding the legality of conventional bead locks in California, I
contacted very helpful Public Affairs Officer Chris Johnson. Now,
understanding that the California Vehicle Code book is very big
(over 1,600 pages!), and has many changes every year, Officer
Johnson did his best, with the help of "Commercial" officers, NITSA
and DOT to answer my question:
"Are conventional bead locks against the law?" His qualified answer
is, "As best I know, no, conventional bead locks are not illegal."
Officer Johnson and I both are interested in learning more from you.
Please call him (714, 567-6000) or me, if you have been cited
specifically for bead locks or know the exact facts for someone who
has. In defence of both of us, rumours are unacceptable. We need the
facts, ma’am, just the facts.
Staun Internal BeadLocks are literally invisible with the exception
of the second valve stem and that also appears to be legal. They use
conventional inner tubes, so as of this writing, neither Officer
Johnson nor I see any "street legal" problems with the Staun
Internal BeadLock™ system.
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BEADLOCKS SAFER
From what's been reported from down under, they may even make
controlling highway blowouts more manageable. One mate reports that
he unknowingly drove 20 km (~12 miles) at 100 kph (~ 66 mph) on
unnoticed front flat. The tire was thrashed, but the rim survived.
What's really amazing to me is that the driver was unaware of his
problem until it was flagged by a friend on the highway. That
appears to make a flat pretty controllable. The inflated BeadLock™
adds a “pneumatic” two or three inches between the rim and the
ground, as above, thereby making it easier and safer to pull to the
side of the road or trail (Figure 4). This should save your rims, if
not the tires, too. More experience will confirm or deny this.
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HOW IT WORKS
As the BeadLock's tube (above) inflates through its own valve stem,
(shown right), it expands until it reaches the limits of the
polyester reinforcing case assembly (all shown above, left). The
hefty polyester case top keeps the tube “down” thereby dictating a
very low profile. This in turn leaves the remainder of the tire
(tire air chamber) to be inflated to your desired pressure. This
space accommodates low pressure flex as needed.
Note the air pressure force arrows (above right). That force, all
the way around, at the beads, is countered by a force at the rim.
These two forces pinch the tire beads to the rim, both inside and
outside.
A conventional tubeless tire secures the beads to the rim in the
same way, but surprisingly enough, the Staun Internal BeadLock™, in
conjunction with the tube and case assembly, also take advantage of
the holding forces above and below the bead, not just at the bead.
The tube and case surround the bead, top to bottom and left to
right, bringing all of these forces together to act like a strap.
This provides additional bead holding force. It is also why one tire
expert recommends that you run tubes in tubeless tires if you air
down.
Without the BeadLock™ tube, as with a conventional tubeless tire,
the lower portion of this "strap" is missing. The top part of the
strap is there by virtue of the tire, but there is nothing beneath
the bead to complete the “strap effect.”
If you are wondering how the air gets in and out of the tire air
chamber, you’re very sharp! Without what’s shown just above, the
tube would cap shut the regular valve stem shown. This picture shows
how an air channel is created by the air channel walls and another
piece, the air channel floor, not seen. Also be aware that the tire
(bead) is not shown for clarity |
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Check our Price List for Sizes and Pricing, additional sizes are
available on a special order basis
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FIVE YEAR WARRANTY ON THE BEAD LOCK CAP AND ONE YEAR ON THE TUBE!
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For more
information including an installation video, Please check out Staun
USA's website at:
http://www.staunproducts.com/beadlock.php
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