has been over a century from the time Dunlop patented his 'mummified wheel'
to the modern radial tyres of today. Yet with all the improvements a tyre
has undergone, one thing remained unchanged, which is only when it is
inflated to the optimised level and that inflation is kept constant that
it can deliver maximum comfort and performance. This is one of the basic
reasons all tyre manufacturers try to focus on in the development stage
of a tyre which can have the best air retention ability. Usage of a tube
or an extra air container within the tyre was regarded as the best solution
for many years.
may come as a surprise to many readers that in 1903, engineer Paul Weeks
Litchfield, then in his early 20s, was granted a patent for the first
'tubeless' tyres. He later rose to be the chairman of the Board of Goodyear
in the year 1940. Just like many other patents, which were granted during
that period, this concept was not pursued until late 1939 when the requirement
for the first amphibious tyre was felt. The 120x33.5 - 66 smooth tread
Marsh Buggy tyres, by far the largest tyres produced then, were used on
Admiral Byrd's Snow Cruiser. This vehicle was capable of carrying very
heavy loads over all sorts of terrain, even float on water. These were
off-the-road tyres, flexible but inextensible pressure vessel that were
pre-stressed and skin-stressed by air pressure. To produce such tyres
Goodyear at Akron employed the idea of Litchfield, using nylon cords for
the first time and a newly developed synthetic rubber compound called
Chemigum to line the inner casing of this tyre to lighten its weight and
eliminate the tube.
The Second World War highlighted the need for reliable tyres as loss of
air or punctures cost precious moments or even endangered lives. Though
the tubeless concept was not used during the war, subsequent development
of tyres with a 'run-flat' capability by introducing tubes, which had
a special construction of a sealant on the lower side, this allowed it
to run without an air loss even after a penetration. The added weight
of the tube made the steering wheel heavy and restricted speed. They were
used on low speed trucks, which traveled on areas with puncture hazards
like wrecker's equipment, dock and warehouse vehicles, and other utility
reduce weight lifeguard tubes were introduced, having two air chambers,
the outer rubber tube with a thick canvas tube inside. In case of a blowout
only the outer chamber gave way, while the reserve air in the thick canvas
tube would not allow the tyre to be completely deflated allowing the vehicle
for a safe straight line gradual stop.
After the war a more determined effort towards elimination of the inner
tube was sought as it was considered the main source of service trouble
and failures while being clearly superfluous and costly. Experiments were
therefore conducted both in the USA (initially by Goodrich) and in UK
(by Dunlop), towards providing a near perfect seal between the tyre bead
and rim, under all service conditions. This meant that the tyre had to
run even at low inflation pressures or with a penetration to a safe distance
without loss of vehicle control. It was in the year 1954 that the first
commercially realised tubeless tyre was fitted as original equipment,
by the now defunct Packard marque.
During the mid 1950s and early 1960s, India too manufactured tubeless
tyres, which were not only supplied as original equipment for the cars,
but also had a number of sizes meant for the replacement market. While
the rest of the world accepted this new technology and by the middle of
1962, nearly all commercial vehicles, trucks and passenger cars used tubeless
tyres, we in India reverted to the old tube-tyre theory. Even though most
companies in India still manufacture tube-type tyres, many have the tubeless
technology available with them and do manufacture tubeless tyres meant
for export only.
Tubeless tyres have reappeared in the Indian scenario but many users are
reluctant to use them. Some fit tubes in them. So which is actually better?
Let us see where the construction difference lies. Apart from the basic
construction, which remains the same with the run of the cords distinguishing
the type of tyre construction, whether it is a cross-ply or a radial ply
one; the main difference lies in the application of the inner liner of
the carcass. Whereas in a tube-type construction the inner liner acts
as a medium for reducing friction between the cord body and the tube,
in a tubeless construction this is the tube itself. Thus the inner liner
in a tubeless tyre is made up of a Halogenated Butyl rubber like Chlorobutyl
or Bromobutyl for better air impermeability together with high heat and
Though compounds used in a tubeless or a tube type tyre may vary, the
other major difference lies in the bead area of the tyre. While considering
a radial tyre both type of tyres have a flexible yet rigid bead, where
the bead bundle is very thin and the stability of the tyre is enhanced
by the bead apex or bead filler controlling it, in a tubeless it also
has to maintain the air pressure within. Thus the bead heel in the tubeless
sits more tightly within the flange of the rim, and to ensure this tight
fitting most tyre manufacturers add an extra wrapping over the bead area.
This enhances high-speed performance while achieving a better cornering
ability on the tubeless.
other advantages are the absence of a tube make the tyre lighter in weight,
thus has less chance of vibrations, which means that it leads to a better
fuel saving. Even the rolling resistance in a tubeless radial is lower
when compared to a tube type radial. This is due to the fact that the
tubeless tyre sidewall is more supple as there is no internal body to
create a friction. This also helps the tyre to run cooler as it eliminates
heat generation caused by the internal shuffling of the tube.
The inner liner also acts as an absorbent during a nail penetration making
the nail act like a plug and therefore the tyre has a slow leak and not
a sudden deflation as it occurs on a tube- type tyre. This can be illustrated
by a simple example. Pierce an ordinary balloon with a pin and it disintegrates,
while sticking a cello tape on the balloon would enable the pin to penetrate
without it bursting.
Similarly by comparing a tubeless tyre to a balloon that is not fully
inflated, when squeezed this would deshape to certain extent before it
bursts. Thus a tubeless can flex over an object, giving it a better impact
resistance than a tube type one.
Personally, I feel that a tubeless tyre is more beneficial than a tube
type tyre, but yet many people feel that since a local puncturewalla cannot
attend to a tubeless it may be a bad proposition to use them. Generally
it is quite simple and sometimes easier to repair a tubeless tyre than
a tube type one. Of course there still remains one important criterion
that the repairer must have proper tools and equipment to handle the same,
which is essential for tube-type tyres as well. I still maintain that
utmost care and regular checks should be carried out at regular intervals
to get the best from your tyres. Secondly most tyre companies worldwide
do not recommend use of tube in tyres lower than 60 aspect ratio. The
other factor is the safety given by a tubeless may not be comparable with
a one using a tube, as my case study will show.