Here is a quote from an article:
"First of all, it helps to know the difference between a radial and a bias
ply tire. To understand the difference, it helps to know a little bit about
tire construction.
A tire is nothing more than a bladder for air. It is made of rubber
reinforced with some sort of fiber (once they were reinforced with canvas,
now they're reinforced with
kevlar -- times have changed). The rubber keeps the air in, and the fiber
keeps the tire together, in addition to importing shape characteristics to
the tire. The fibers are
layed out in layers, each layer consisting of fibers lain in parallel, and
impregnanted with rubber. The final element is the bead, which is simply a
wire put around the edge of the tire to help it clamp to the rim.
The way these layers are placed on the tire is what determines whether the
tire is a bias-ply or radial tire. In short, a radial is a tire where the
threads in the ply are lain
perpendicularly to the bead. This gives them the appearance of radiating
from the center of the tire, thus the term radial. Bias ply tires are a
little different, because the angle
of the fibers is at a bias to the bad, usually at an angle of about 70
degrees. For reference, a "zero degree" layer would be a belt around the
circumference of the tire.
Okay, so what does it mean? Well, a bias-ply tire requires a minimum of two
layers to support the sidewall and the tread. The layers are fairly stiff,
and essentially must scissor against each other to flex. This makes the tire
run hotter. A radial tire needs only one ply, and thus is not only softer,
but runs much cooler, and weighs less to boot.
Advantages all around -- lighter, cooler, more compliant. This means that
not only can you run a softer compound for radials, but it will provide
better grip since it can
conform to the road better. Great!
But wait! There's a catch -- radial tires require wider rims to support the
same tire width. That means that a 120/80 bias ply tire would work on a 2.5
inch rim, but a
120/80 radial would need a 3.0 inch rim to support it properly. Why does a
radial need a wider rim? In simplest terms, a radial tends to have a softer
sidewall, and a
wider rim with a similar aspect radial puts less load on the sidewall,
causing it to distort less under load. Most radials are designed for wider
wheels, and putting them on a
narrower rim will distort the cross-section of the tire and affect the
hndling of the bike -- almost always negatively."
Mix at your own risk.
Mike Oberle /1990 Shiny-Black MonkeyMax
VMOA #1355 / AIM - "Injuhneer"
-----Original Message-----
From: V-Max [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 02, 2000 3:28 PM
To: [EMAIL PROTECTED]
----------------------------------------------------------------------
Date: Mon, 2 Oct 2000 13:39:27 -0500
From: " BRADFORD" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Subject: Re: Radial, bias, poly, etc
Message-ID: <000501c02ca0$190c4d40$08d0c440@u5z5r8>
THE RELATIONSHIP BETWEEN FRONT AND REAR ARE SO VARIED. SUCH AS, AT
SPEED THE FRONT WHEEL IS TURNED OPPOSITE THE LEAN ANGLE. I WILL BE USING
RADIAL FRONT AND BIAS REAR. [ AGAIN ] PARDON THE CAPS BRADFORD
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