FEATURE I 30 YEARS OF THE 0° STEEL BELT RADIAL TIRE
P104
"Our French competitors
[Michelin] were the first to ex-
plore this construction," admits
Misani. "They could go in the
direction of having a good tire
that lasted a long time on the
motorway, but not a good tire
when you go to a racetrack. It
was either one or the other."
Metzeler could see the pos
-
sible benefit of the usage of
steel and thus pushed the devel-
opment further.
"When you are leaning into
the corner, the tire has a strong
pull from the carcass, so the
intrinsic stability of steel versus
textile or cable could help. And it
did help," Misani says. "What we
found is a zero-degree construc
-
tion reacts with half the force of
its predecessor. That means you
have half the disturbance, so the
tire is lighter and is more stable.
"We called the tire Dr. Jekyll
and Mr. Hyde. It would work well
when you rode calmly on the
motorway, even when worn out,
but it would still perform well
when reaching lean angles of
45° or more."
Granted, this is the early
1990s and long before the 60°-
plus you can get from today's
street tires.
It was left to Pirelli/Metzeler's
Head of Global Testing and
Technical Relation Salvatore
Pennisi to conduct the first on-
road tests.
"We had a GSX-R750," Salvo
said. "I tested this bike on a
motorway in a very fast condi
-
tion, and with our radial tire the
handling, in terms of sporty use
and so on, was excellent. But in
the motorway, it was a little bit
nervous, we could say. With the
first prototype of zero-degrees
steel belt, the speed you could
hold was incredible. Full speed!
There was just one problem—
this tire was not possible to
lean [into the corner]. It was not
stable, so we had to completely
redesign the tire."
The instability of the first 0°
steel belted radial tire meant a
complete rethink on how street
tires were conceived and con
-
structed. The old way of thinking
was tires needed to be almost
triangular shaped, with small
Salvo (center, with white
helmet) and the Suzuki
Germany/Motorrad Magazine
team after they broke six world
records in 24 hours in 1993.
