On Wed, 11 Dec 2002 19:31:20 -0500, Jon N. Benignus said...
>
> > Think about it this way, you are exposing more surface area of the tire to
> > the outside elements, allowing "more" of the tire to come in contact with
> > the road surface, this is especially true off-road. That is why the grip is
> > so much better.
>
> When you sipe, or groove a tire, you are REMOVING rubber that once came in
> contact with the pavement. Less surface area = less traction. The reason you
> get better off road traction is the tire now has more edges in which to dig
> into the surface.
> You actually decrease dry pavement traction by siping a tire. That's why we
> dirt track racers groove the tires-to get a "bite", or actually break the
> surface of the dirt or mud. You can't displace pavement, so you use less
> grooves to put as much tire surface as possible on the road.
I'm no expert on the subject, but I just bought a new set of BFG ATs
and had them siped. The siping process did *not* remove any rubber
from the contact pads -- it simply sliced them. No grooves per se,
just cuts. On day one, unless you looked real close, you couldn't
really even see the cuts. After a few thousand miles, the cuts are
more apparent.
Now, I'm not saying it did anything to the dry pavement traction one
way or 'tother. The way it was described to me, the siped tire will
grip better in snow and mud because as the little sliced nubs on the
tire flex as they transfer pwoer to the surface, there are more sharp
edges to gain traction, but there is neither a decrease nor an
increase in "surface area" contact on dry pavement. One major benny
they *do* tout is better wear due to improved heat dissipation.
It could be that we're confusing siping, which a patented process done
ONLY by a machine named after its inventor, Mr. Sipe, with grooving.
I've run grooved slicks when I used to race go-karts on dirt ovals,
and grooving a tire uses a heated "grooving iron" that literally
gouges out a trough of rubber. Siping doesn't do that -- it presses
the tire agains a sharpened spiral blade that just slices into the
tread.
-- Grady Ogburn (Denver, AIM: JGradyO) Black '98 Sport CC 4x4 5.2l, 5 Speed, 3.55 LSD K&N GenII, MP TB, JET II, MSD 6A, Magnecor 8.5 Wires Mesa Headers & Cat, Gibson/MagnaFlow 3" Exhaust Leer Topper
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