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To some people tyres are a status symbol, to most people they are a necessary
evil, to others, they are Big, Black, Round and Very Expensive. Tyres are an
incredible piece of engineering that contributes to motoring safety. The
gyroscopic forces exerted on a tyre during normal usage is incredible, tyres not
only have to cope with gyroscopic forces during rotation, they also have to be
able to handle the immense lateral forces placed on the side wall during
cornering but also the forces placed on it during acceleration and deceleration.
All this and still give a low noise, comfortable ride and deal with all weather
condition.
John Boyd Dunlop, invented the first practical pneumatic car tyre more than a
century ago, in 1887. Simple ideas can change the world. In 1888, while watching
his son ride a tricycle, John Boyd Dunlop noticed his discomfort whenever he
rode over cobbled ground. He knew the tricycle's solid rubber tyres were to
blame. The solution? He wrapped the wheels in thin rubber sheets, glued them
together, inflated them with a football pump for a cushioning effect - and
created the first commercially viable pneumatic tyre.
Dunlop patented the idea, giving his fledgling Dunlop Tyre Company a head start
over automotive competitors who had already recognised the tyre's many
advantages. Ten years later, Dunlop's invention had almosts entirely replaced
solid tyres. In 1889, Dunlop opened its first tyre plant in Dublin and its first
factory in Birmingham just two years later.
In 1895, the Michelin brothers, built their first pneumatic tyre for the Paris
-Bordeaux - Paris road race, it was fitted to a Peugeot chassis with a Daimler
engine. (The car was named "Éclair") It was the only car on pneumatic tyres,
although completing the race the car was disqualified.
In 1899 the 100 Kphbarrier was broken by Jamais Content. The tyres on the record
breaking vehicle were made by the Michelin Brothers and the tyres were the first
"Low Profiles".
In 1937 Michelin filed patent on a tyre known as the "Metalic" which was the
first Radial plies tyre. It was also the first tyre to use steel plies instead
of Textile plies. (1 steel plies = 20 textile plies).
1949, The year the Radial tyre was first commercialised on the replacement tyre
market.
In 1951 the first production car to be made and sold on a mass commercial basis
was the Citroen 2CV. It was also the year that the first race was ever won using
a Radial plies tyre. (Le Mans 24 hour). Citroen, Panhard and Peugeot were the
first manufacturers to supply cars with the Radial Tyre.
Q. What does the writing on the side of the tyre mean?
A. There is a huge amount of information on the side of a tyre from the tyre size to where it was made and even the date that it was made. The important part is the size of the tyre and this is written as 205 / 65 / R14 91 H
205 is the Section width
205 means that the tyre is 205 millimetres wide, measured from side wall to side wall, with the tyre inflated to the correct pressure but not under load.
65 is the Section height, Profile, Aspect Ratio, Series
All the above names apply to the same part of the tyre, it is measured as a percentage of the section width. In this case the height of the tyre is 65% of the Section width of the tyre. The lower this number, the lower the profile of the tyre, hence the term, low profile tyres.
R is the design of the tyre
In this case it is a Radial ply tyre. (Invented by Michelin in the 1930s) The other design of tyre is a Cross ply or Bias ply tyre
14 is the rim Size.
This tells you that this tyre is to be fitted on a 14 inch rim, (the
round metal bit)
91 is the Load Index
This is the maximum safe weight that this tyre can carry in conjunction with the speed index number.
H is the speed index
This is the maximum speed that this tyre can safely travel at in conjunction with the load index.
Click here for more tyre briefs.
For more information about tyre pressure, click here.
Click here for more facts about tyres.
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